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Pillars of Modern El ectroch emist by A. K. Shukla and T. Prem Kumar ry

lthough there is some archaeological evidence which suggests that some form of a primitive Birth Pangs Abattery (sometimes called a Baghdad battery) was used for in Mesopotamia ca. 200 BC, t was only in the sixteenth century as we know it today had its genesis that began to be understood. in the pile of crowns of in 1800. The IThe English William Gilbert (1544-1603), known as the “father of inspiration for his studies might have come from the ” for his on , famous frog leg experiments of Galvani, who, however, was among the first to experiment with was content to conclude that the phenomenon was of electricity. He devised methods to produce biological origin. A metamorphosis took place with William Gilbert as well as strengthen magnets. The first seminal contributions from John Daniell and Michael electric generator was constructed by the . From such humble beginnings, electrochemistry German (1602-1686) in 1663. The device generated today has matured into a multidisciplinary branch of by between a large study. Built on the precision of and depth of ball and a pad. By the mid-1700s , it encompasses , physics, the French Charles François de biology, and . Cisternay du Fay (1698-1739) discovered The uniqueness of electrochemistry lies in the fact two types of static electricity. He found that the application of a potential or can that like charges repel each other while help overcome kinetic limitations at low tempera- the unlike charges attract. Moreover, he suggested that electricity consisted of two tures. Moreover, electrochemical processes can be tuned fluids: a vitreous form (from the Latin Otto von Guericke to obtain chemically and sometimes stereochemically- vitrum for ) or positive electricity; and specific products. Electrochemical reactions are also a resinous form or negative electricity. sensitive to -surface characteristics and Later in the century, the two-fluid theory composition, which opens up several of electricity was opposed by the one-fluid analytical and characterization avenues. Like many theory of (1706- 1790). In 1781 Charles-Augustin de forward thinkers who have strived to make life easier (1736-1806) propounded the for us to live, history pages are littered with the names, law of electrostatic attraction. Coulomb, some of them long forgotten, of those who have made the SI unit of charge, is named in his electrochemistry what it is today. This article is an honor. attempt to provide a glimpse of these pillars of electrochemistry through their contributions. Charles-Augustin (continued on next page) de Coulomb The Electrochemical Society Interface • Fall 2008 31 Volta described his invention in a letter dated 20 March 1800 to Sir Joseph Banks (1743-1820), then President of the Royal Society. It was titled “On the Electricity Excited by the ECS Mere Contact of Conducting Substances of Different Kinds.” Banks showed the letter to Anthony Carlisle (1768-1842), a (continued fromClassics previous page) surgeon. Enter chemist-engineer William Nicholson (1753-1815), a friend of Carlisle, and together they assembled It was at this time, when insights into the new phenomenon a . In their attempt to determine the charges on the of electricity were growing, that electrochemistry had its upper and lower plates with the help of an , they birth pangs with the Italian and anatomist Luigi put drops of on the uppermost disc (for better contact!), Galvani (1737-1798) proposing what he called animal and to their surprise found bubbles of evolving. Soon they electricity. In a 1791 essay titled De Viribus Electricitatis in Motu found that the battery’s terminals dipped in water generated Musculari Commentarius, Galvani proposed that animal tissue and . They had discovered or contained an unknown vital force, which activated driven by . and muscles when touched with probes. According to Months later, (1776-1810) Galvani, animal electricity was a new form of electricity in improved upon the experiments of Carlisle and Nicholson and addition to the natural electricity produced by (or created a set-up to collect oxygen and hydrogen separately. by the and torpedo ray) and the artificial static Subsequently, he also invented the process of electroplating. In electricity produced by friction. The idea of an animal electric fact, Ritter might have made his discoveries earlier than Carlisle fluid was rejected by Alessandro Volta, who argued that and Nicholson, but could not possibly have published the results frog’s legs responded to differences such as metal temper and because of his duties as an apothecary. Ritter’s observation of composition. However, Galvani stood by his version and even thermoelectric potential (the electrical potential at the junction demonstrated muscular action with two pieces of the same of two dissimilar kept at different ) in 1801 material. also anticipated the 1821 discovery of thermoelectricity by Interestingly, Galvani’s experiments at the University of the Estonian-German physicist Bologna on the physiological action of electricity involved (1770-1831).* Ritter’s experiments on the electrical excitation not only live frogs but also frog legs that had been detached of muscles included subjecting himself to high , which from the body. He showed that muscle contractions in frogs might have led to his early death. In this same time period, and other animals could be triggered by an electric current English physicist and chemist Henry Cavendish (1731-1810) from a Leyden jar or a rotating static electricity generator. made his famous quantitative experiments on the composition The twitching of the frog’s legs marked the experimental of water and also came out with a version of the ’s law phenomenon that has come to be known as bioelectrogenesis. for electrolyte . He is also known for the famous In fact, Galvani’s experiments not only helped establish the Cavendish experiment for the measurement of the density of basis for the biological study of neurophysiology, but also led the . Not too comfortable with publicity, Cavendish lacked to a conceptual change by acknowledging nerves as electrical the acclaim that is due to a person of his scientific caliber. In conductors rather than as mere water pipes, as held by the fact, several of his findings were not published. For example, Descartes school. Galvani’s name came to be associated he recognized that the force between a pair of electrical charges with galvanization (a technique of administering electric is inversely proportional to the distance between them, the shocks, although another term, faradism, was also used for credit for which goes to the French physicist Coulomb. There the technique). The word galvanization has shed this archaic are at least two physical structures that should recall him to the meaning, and is applied at present to a protective treatment present generation: a square in London, named after him, and of with . Galvani is also immortalized in the English the Cavendish Physical Laboratory at Cambridge University. word galvanize, which means to stir up sudden/abrupt The technique of electroplating action. was unveiled by Italian chemist Luigi Brugnatelli (1759-1828) in 1805. His experiments on plating were performed with a Voltaic pile as the Nineteenth Century: The First Half power source. Because he was rebuffed The credit for laying the cornerstone by Bonaparte, Brugnatelli was of modern electrochemistry must, forced to keep his results in low profile. however, go to Alessandro Giuseppe Meanwhile, Antonio Anastasio Volta (1745- (1766-1828) and 1827), a professor of natural philosophy (1761-1815), in their attempt to use at the University of Pavia, who showed Sir Humphrey Davy electrochemistry to purify , in the early that animal tissue ended up discovering other elements: was not necessary for the generation palladium and rhodium (Wollaston) and of current. He argued that the frog legs iridium and (Tennant). Drawing used in Galvani’s experiments served inspiration from Ritter, Carlisle, and Nicholson, Sir Humphrey Davy (1778- Alessandro Volta only as an electroscope and suggested that the true source of stimulation was 1829) used electrolysis to isolate metals the contact between dissimilar metals. such as , , , He called the electricity thus produced metallic electricity. , and . He concluded In fact through his voltaic piles, consisting of alternating that electricity induced chemical action discs of dissimilar metals, he effectively demonstrated the and that chemical combination occurred first electrochemical battery. The epochal invention formed between oppositely charged substances. the basis of modern batteries and a host of other galvanic Jöns Jakob Berzelius phenomena including and sacrificial . It also marked the first time that a continuous electric current was ______generated. Volta, whose work effectively rejected Galvani’s animal electricity theory, coined the term galvanism. *Seebeck, however, failed to recognize that an electric current was generated when a bimetallic junction was heated. In fact, he used the term Napoleon Bonaparte honored Volta with the title of Count thermomagnetic current to describe his discovery. The Seebeck effect forms of Lombardy. Volta is also credited with the discovery and the basis of the thermocouple, which is among the most accurate devices for isolation of methane. Alessandro Volta is immortalized in the measuring . The opposite phenomenon, the Peltier effect, which unit , a nomenclature that dates back to 1881. is the generation of a temperature difference brought about by a current in a circuit with two dissimilar metals, was observed a decade later.

32 The Electrochemical Society Interface • Fall 2008 A contemporary and rival of Davy, Jöns Jakob Berzelius who in 1839 showed that impinging on an electrode (1779-1848) also made important contributions to immersed in a conductive would create an electric electrochemistry. Berzelius found that electrolysis resulted in current. In 1830, William Sturgeon (1783-1850), another the formation of elements at the poles of the cell, which led scientist who worked on sustained current generation, him to suggest that were charged and compounds were produced a battery with longer life than that of Volta by formed by neutralization of charges. This was his dualism amalgamating the zinc. was found to be a cure for theory, which, however, did not apply to organic compounds. , a process by which a thin film of hydrogen Berzelius also established the law of definite proportions. He bubbles formed over the positive electrode. The thin gas film is also credited with the discovery of several new elements led to high internal resistance in the Volta pile, resulting in including , selenium, and thorium. It was he who reduced current flow. In 1832 Sturgeon constructed an electric created a logical system of symbols for elements (H, C, Ca, Cl, motor. The same year witnessed Hippolyte Pixii (1808- O, etc). With the work of Davy and Berzelius, chemistry was 1835), a French instrument maker, build the first dynamo. never to be the same again! Later, using Sturgeon’s commutator, Pixii built a A momentous discovery was made in dynamo, which was the first practical mechanical generator parallel by Danish natural philosopher of electric current. Hans Christian Ørsted (1777-1851), In 1836, who observed the magnetic effect (1790-1845) unveiled a two-fluid battery, of electric current in 1820. André- which was the first battery to provide a Marie Ampère (1775-1836), who constant and reliable source of current took the cue from Ørsted, conducted over a long period of time. Daniell extensive experiments and formulated used a vessel that served both his findings mathematically. Then as the positive pole and the container. came another formulation connecting Inside the copper vessel was an earthen , current, and resistance—Ohm’s pot with a zinc rod (the negative pole) André-Marie Ampère law—which came through the work and dilute sulfuric . The copper of the German physicist vessel was then filled with a solution of (1787-1854) in 1827. Ohm’s discovery was initially ridiculed John Frederic Daniell copper sulfate. The porous pot served by his contemporaries. However, by 1833 the fundamental as a barrier, preventing mixing of the importance of Ohm’s law in electrical circuit analysis was liquids. Although Daniell is famous for his invention of the recognized and Ohm came to be considered the Mozart of two-fluid battery, he is less known for his 1820 invention of electricity. the dew-point hygrometer for the measurement of relative (1791-1867) is humidity. considered to be one of the greatest The technique of electroforming was introduced in 1838 in history. Some refer to by Boris Jakobi (1801-1874). Jakobi applied his technique to him as the greatest experimentalist the printing and coinage industries. Soon an electroforming ever, especially because his work on shop was set up at the Governmental Papers Department, electricity found expression in day-to- which was noted for depositing 107,984 kg of copper and 720 day technology. , the SI unit of kg of gold for decoration of architectural monuments and , and the , cathedrals in St. Petersburg and Moscow. are named after him. He invented Sir William Grove (1811- the dynamo, predecessor to today’s 1896) invented the first in electric generator. His concept of 1839. Grove is also credited with the Michael Faraday lines of flux emanating from charged invention of the Grove’s cell: bodies and magnets provided a way to zinc in dilute as the visualize electric and magnetic fields, and was crucial to the and platinum in concentrated nitric acid successful development of electromechanical devices, which as the , separated by a porous dominated engineering and for the remainder of the pot. Because the cell could sustain high 19th century. The , a phenomenon he named current output, it became a favorite with diamagnetism, was also his discovery. In his work on static the early American telegraph industry. electricity, Faraday demonstrated that charge resided only But it was replaced by the on the exterior of a charged conductor, and that the exterior Sir because of the poisonous it charge had no influence on anything enclosed within a emitted and because of its inability to conductor, a shielding effect we now use in . deliver currents at constant voltage (the voltage dropped as Faraday worked extensively in chemistry too, discovering the cell discharged due to depletion of nitric acid). However, substances such as benzene and the first clathrate , his invention of the gas voltaic battery, the forerunner of liquefied such as , and proposed the system modern fuel cells,* made him the “father of fuel cells.” In his of oxidation numbers. He also discovered the laws of experiments that led to the invention, he sought to reverse electrolysis, by which he quantified electrochemistry, and the electrolytic splitting of water, to popularized terminology such as anode, cathode, electrode, recombine hydrogen and oxygen and , terms largely created by William Whewell (1794- to produce water and electricity. 1866). He rejected the traditional fluid theory of electricity His background in law and science and proposed that electricity was a form of force that passed opened up the practice of patent and from particle to particle in matter. related laws. A major problem with the Volta pile In 1841, Robert Wilhelm was that it could not provide current Eberhard Bunsen (1811-1899) led for a sustained period of time. In 1829 the way for large scale exploitation of Antoine-Cesar Becquerel (1788- fuel cells by replacing the expensive 1878) constructed a constant current platinum in the Grove’s cell with a cell, which was a forerunner of the electrode. The modified version well-known Daniell cell. His acid–alkali was popularly known as the Bunsen cell could deliver current for an . Becquerel’s studies on electrodeposition (continued on next page) ______of metals helped validate Faraday’s laws *Although the first fuel cell was constructed in 1839, the term fuel cell of electrolysis. The credit for came into vogue only in 1889 with and Charles Langer’s Antoine-Cesar Becquerel technology must be given to Becquerel, attempt to build the first fuel cell using air and industrial coal gas as feed gases. The Electrochemical Society Interface • Fall 2008 33 Electrochemists connect the name Josiah Latimer Clark (1822-1898) with the standard used for measuring the standard . This English engineer was ECS a very versatile inventor, known for his work on wireless , particularly the Anglo-American Atlantic cable. It (continued fromClassics previous page) was Clark who introduced the notion of volt as the unit for voltage. In 1872, Clark invented the first standard cell with battery. To students of science, the name Bunsen is associated mercury and zinc in a saturated solution of with a burner, although the actual credit for the burner should . It had a large temperature coefficient of –0.00115 go to a technician by name Peter Desaga of the University of V/°C. Moreover, it was prone to cracking where the platinum Heidelburg. It must be pointed out that Bunsen fine-tuned the entered the glass cell. Today, we use the Weston design of the burner to suit experiments in physics that he cell as the standard for the potentiometric measurement of carried out with Gustav Kirchoff, a Prussian physicist. The two standard electromotive force. invented the Bunsen-Kirchoff spectroscope. Between 1858 and 1860 the American inventor and This was just about the time when the German chemist industrialist Isaak Adams, Jr. (1836-1911) pioneered the Friedrich Wöhler (1800-1882) overthrew the vitalism theory technique of nickel plating, which immediately was exploited that a vital force was necessary to make organic compounds by on a commercial scale. He was the son of Isaac Adams, Sr., synthesizing urea from ammonium cyanate. Adolf Wilhelm the inventor of the Adams power press. Adams also had other (1818-1884) also was another chemist credentials as an inventor: the vacuum-tube carbon burner who believed that organic compounds could be made from incandescent electric bulb, which he invented in 1865, 14 inorganic ones. He converted carbon disulfide, an inorganic years prior to a similar invention by Edison–Swann; breech- compound into , an , in several loading rifles; and copper plating on steel for bonding rubber synthetic steps. Kolbe also made salicylic acid (the Kolbe- to steel. Schmitt reaction). Kolbe was the first to apply electrolysis for The year 1859 witnessed an organic synthesis. He showed that electrolysis of carboxylic invention that was to revolutionize the led to decarboxylation. Loss of during world of portable power: the lead-acid the reaction led to dimerization of the resulting alkyl radicals battery by the French physicist Gaston to symmetric compounds (Kolbe synthesis). Planté (1834-1889). Planté’s storage During 1842 and 1843, George Gabriel Stokes battery used lead plates as electrodes (1819-1903) published a series of papers on the motion of and delivered limited currents because incompressible fluids. They became fundamental to our the positive electrode had very little understanding of electrolyte solutions. Sometime around 1845, of active material. In 1881 Camille in what was to mark a revolution in industrial electroplating, Alphonse Faure (1840-1898) replaced John Wright showed that potassium cyanide was a suitable Planté’s solid lead plate with a paste of Gaston Planté medium for plating and gold. In 1857 electroplating was lead oxide, which led to faster formation applied to costume jewelry, and soon electroplaters cashed in kinetics and improved efficiency. The significance of Planté’s on a booming economical jewelry market. invention can be gauged by the fact that the technology of One of the foremost of the nineteenth century, the lead-acid battery has changed little since its invention Prussian-born Gustav Robert Georg Kirchoff (1824-1887), except for changes in electrode design and casing materials, formulated what are today known as Kirchoff’s laws. When he and that other battery chemistries are yet to approach the announced the laws in 1845, he was still a student, although lead-acid battery in terms of certain electrical capabilities and in their final forms the laws became known only in 1854. The economy. laws help in calculating the currents, voltages and resistances Seven years later, in 1866, French scientist Georges in multi-loop electrical networks. The laws embody the Leclanché (1839-1882) patented a with a porous principle of conservation of charge and energy. In association pot containing dioxide and carbon as the positive, with Robert Bunsen, Kirchoff introduced the spectroscopic and a zinc rod as the negative. The electrodes were immersed method of chemical analysis, leading in the process to the in an electrolyte of ammonium discovery of cesium (1860) and (1861) as well as . The Leclanché wet cell was the unfolding a new technique for discovery of new elements. forerunner to the zinc-carbon which became the world’s first widely used primary power source. Leclanché’s Nineteenth Century: The Second Half cell was rendered dry by the German scientist Carl Gassner (1839-1882), In 1853 Johann Wilhelm Hittorf (1824-1914), a when he cleverly configured the cell German physicist, noticed that some traveled more with zinc as a container and negative rapidly than others under an applied current. This finding led electrode. Gassner also employed zinc to the concept of transport number. A couple of years later, chloride in the cathode mix so as to Adolph Fick (1829-1901), at a mere 26 years, building on the Georges Leclanché reduce the wasteful corrosion of zinc Fourier’s theory of equilibrium, developed a mathematical during idling. The market for dry cells concept by which he showed that diffusion is proportional received a boost with the use of tungsten filament in to gradient. That was in 1855. However, in 1909. experimental proof of the concept was not established for the Gabriel Lippmann (1845-1921) received the 1908 Nobel next 25 years. He was proficient in physiology, mathematics, Prize in Physics for inventing the color photographic plate, and physics, and made another distinctive contribution in the but to electrochemists he is associated with the capillary form of a monograph entitled Medical Physics, in which he dealt , which he invented in 1872. This instrument, with several topics including mixing of air in the lungs, heat based on the extreme sensitivity of mercury meniscus in a economy of the body, physiology of muscular contraction, capillary tube to applied potential, was subsequently exploited and of circulation. Medical physics had for measuring electrocardiograms. His versatility of interests to wait for nearly a century for another monumental book, can be noted in the fact that he was also the inventor of the which came through Otto Glasser (1894-1964). Cardiologists coelostat (a long-exposure instrument that allows a region note that Fick made a distinctive contribution in 1870 when of the sky to be photographed by compensating for Earth’s he described how balance could be used to measure movement) and conducted research in various areas including cardiac output, thereby presenting a mathematical basis of piezoelectricity, seismology, and induction in resistance-less physiological activity. circuits. Lippmann was a research advisor to Marie and a professor to Pierre Curie.

34 The Electrochemical Society Interface • Fall 2008 Between 1875 and 1879, the . He thus became the German physicist Friedrich Wilhelm first to demonstrate that light could be Georg Kohlrausch (1840-1910) used to generate electricity without heat working with solutions of a variety of or moving parts. salts and acids developed the law of In his thesis published in 1884, independent migration of ions. He was Swedish physical chemist and the 1903 the first to apply Chemistry winner Svante for electrochemical investigations. By August Arrhenius (1859-1927) using alternating current, he was able suggested that dissolving to avoid deposition of decomposition in water resulted in varying degrees of products on the electrode surface and of the electrolytes into ions. Friedrich Kohlrausch obtain results with high precision. The degree of dissociation depended Kolrausch also demonstrated that ionic not only on the of the electrolyte conductivity increased with dilution. He was also noted for but also on its concentration—the his work on autoionization of water, thermoelasticity, and greater the concentration, the lesser thermal conduction and for his precision measurements of the dissociation. The concept of magnetic and electrical properties. , a quantity that The time was when the electricity was still in its infancy and relates the actual number of ions at the identification of the itself was to happen ten years any concentration to their number later. At this time emerged a man who contrived to answer a upon high dilution, was born out of question by Maxwell whether the resistance of a coil excited Arrhenius’s studies. His collaboration by an electric current was affected by the presence of a . with Ludwig Eduard Boltzmann Edwin Herbert Hall (1855-1938), an Jacobus van’t Hoff (1844-1906) and Jacobus Henricus American physicist well ahead of his van’t Hoff (1852-1911) led to theories time, discovered what we call the Hall on the ebulioscopic properties of effect in 1879. The discovery remained solutions. Latvian chemist Friedrich a curiosity for nearly a century until the (1853-1932), the emergence of semiconductors that could 1909 Nobel Prize winner, extended produce significant Hall voltages. Today, Arrhenius’s theory to the electrical Hall effect is used in the primary circuit conductivity and dissociation of organic of electronic ignition systems. acids. Ostwald also propounded a theory This was also a momentous period for of solutions based on ionic dissociation. the growth of electrochemistry, marked In 1884 he came out with a definition Edwin Herbert Hall by its marriage with thermodynamics. of . Ostwald is also credited The architect of this transformation was with the invention of the viscometer. the American scientist Josiah Willard Friedrich Ostwald The application of electrolysis for Gibbs (1839-1903). (Ed. Note: In winning aluminum from aqueous 1967, there was a serious discussion solutions of aluminum salts ended up in about renaming ECS as the J. Willard the formation of aluminum hydroxide. Gibbs Society.) He was a true genius However, in 1886 two young scientists, and drew on the concepts of great Paul Louis Héroult in and men like Johannes Diderik van der Charles Martin Hall in the United Waals (1837-1923) and drew accolades States (both born in 1863 and died from peers such as Maxwell. Even his in 1914), working independently, first paper was a classic and contained succeeded in producing aluminum from his famous formula dU = TdS – PdV. a melt of aluminum oxide in cryolite. Interestingly, Yale University’s first The inventions went through a patch doctoral degree for an engineering thesis of patent litigations before Héroult and was awarded to Gibbs. He also is known Paul Louis Héroult Hall agreed to bury their differences. for his contributions to and Their opened up a electromagnetic theory. new world of industrial applications The nature of electricity came in for -resistant aluminum, which was for much debate during this period. until then considered a prized metal The British physicist James Clerk used in fine jewelry. Maxwell (1839-1871) believed that The theory of electrolytic electricity was the result of polarization dissociation formulated by Arrhenius of the ether or of the medium through inspired another architect of modern which electric current flowed. However, electrochemistry: Walther Hermann Johannes van der Waals in 1881 the German scientist Hermann Nernst (1864-1941). In 1888, Nernst von Helmholtz (1821-1894) basing came out with a theory connecting his theory on Faraday’s laws of electrolysis, which relates the the electromotive force in an charge to the amount of metal deposition, argued that the Charles Martin Hall to the free energy existence of atoms implied the particulate nature of electricity. of the chemical reaction that produces However, proof of the existence of such a particle () the current. He also demonstrated that seemed to contradict Helmholtz theories of electrodynamics, solvents with high constants which were based on the supposed properties of the ether. At promoted the ionization of substances. any rate, the discovery of waves by Heinrich Rudolf His experiments with solutions led Hertz (1857-1894), a student of Helmholtz, helped cement him to suggest conditions under which the theories of Faraday, Maxwell, and Helmholtz. Decades solutes precipitated from solutions. later, Albert Einstein’s general and special theories of relativity The theory of solubility product is helped dismantle the concept of the pervasive ether. also his making. He devised a method Maxwell’s successor at King’s College, London, William to measure dielectric constant and Grylls Adams (1836-1915), along with his student, Richard demonstrated that solvents with high Evans Day, found in 1876 that selenium upon exposure to light produced electricity, by a process we recognize today as (continued on next page)

The Electrochemical Society Interface • Fall 2008 35 the acidity of solutions. Haber is also credited with the invention of the glass electrode, a contribution he made with Cremer, one of his associates. ECS This was also a period that witnessed as many as 1,093 inventions by a single person, Thomas Alva Edison (1847- (continued fromClassics previous page) 1931), nicknamed the “Wizard of Menlo Park.” Although he is most popular for dielectric constants facilitated ionization of substances. inventing the incandescent bulb and Students of know him through the Nernst the phonograph, his unveiling of the equation. nickel– accumulator was no less Tutored by Hermann Kolbe at Marburg and Robert Bunsen a contribution. Simultaneously, and at , Ludwig Mond (1839-1909) became a well independently of Edison, Waldemar known chemist and industrialist. Initially, his interests were Jungner (1869-1924) in Sweden in the production of elemental sulfur, alkali, and . patented the nickel-iron battery. In 1899 He also developed a process (the Mond process) for the Jungner replaced the iron electrode with the more efficient generation of producer gas. In 1889, he and his assistant cadmium electrode. It is interesting to note that in 1899 the Carl Langer developed a hydrogen–oxygen fuel cell with thin world record for road speed was held by the electric vehicle! perforated platinum electrodes. Both Mond and Langer were However, with rapid advancements in internal instrumental in popularizing fuel cells. In their attempt to use engineering, the bottom fell off the electric vehicle market in coal gas as a fuel in fuel cells, they discovered the formation the next three decades. of nickel carbonyl (the described by Lord Kelvin as The year 1898 marked a turning metals with wings) from the carbon monoxide in the coal gas point in organic electrochemistry with and the nickel in the electrode. This observation formed the Swiss chemist Julius Tafel (1862- basis of the Mond process for the extraction of nickel through 1918) demonstrating the use of lead as a carbonyl route. an electrode for the reduction of organic In 1890, inventive genius and businessman Herbert compounds. Tafel, who was both an Henry Dow (1866-1930), best known for his work on organic chemist and a physical chemist, chemistry, developed an electrolytic method for made seminal contributions to organic the production of bromine from . Today, the method electrochemistry and established the is known as the Dow process. An offshoot of this work was Tafel equation connecting the rates an electrolytic production route for chlorine. Slowly, and of electrochemical reactions and with the establishment of the Dow Julius Tafel . The Tafel equation was Chemical Company, he ventured into unique in that it could be applied chlorine chemicals, organics, and later to irreversible electrochemical reactions that could not be into magnesium metal and calcium. By described by thermodynamics. The several contributions capitalizing on the brine sourced from he made in include reduction with the ancient seas in the Midland region amalgams and the Tafel rearrangement. Tafel is also known of the U.S., Dow opened avenues for for introducing the hydrogen coulometer for measurement mining sea resources. of electrochemical reaction rates and pre-electrolysis as a The first to record a human method for purifying solutions. electrocardiogram with the Lippmann’s mercury capillary electrometer was Herbert Henry Dow Augustus Desire Waller* (1856- Twentieth Century: First Half 1922), the French physiologist who in 1887 thought up the idea of Thermodynamic considerations and ionic transport were using the body itself as an electrical the focus of this period. In one of the first approaches to conductor. Willem Einthoven characterizing aqueous solutions, H. Friedenthal in 1904 (1860-1927) improved upon Waller’s suggested the use of hydrogen ion . In what is experiments and instrumentation. In probably the beginning of the concept of pH, Friedenthal also 1893, Edward Weston (1850-1936) found that the product of the concentrations of hydrogen developed a standard cell that was to ions and hydroxyl ions in aqueous solutions was always 1 become the international standard x 10-14. It must be pointed out, however, that the concept of for the calibration of voltmeters. The pondus hydrogenii, or pH, itself was introduced five years later cell was less sensitive to temperature by the Danish chemist Søren Peder Lauritz Sørensen fluctuations than the previous standard, (1868-1939). Edward Weston the Clark cell, and had the additional In what was to mark the beginning of bioelectrochemistry, advantage of possessing a voltage very Julius Bernstein (1839-1917), of the University of , close to a volt: 1.0183 V. demonstrated that the action in nerves Based on his work on electrolysis, was the result of a change in ionic properties of the (1868-1934) in 1898 membrane. He proposed his membrane hypothesis in two showed that different products could parts, the first one in 1902 and the second in 1912. His theory be obtained by maintaining the was based on the work of Helmholtz and Du Bois-Reymond potential of the electrode at different (1818-1896), the “father of experimental .” values. He explained his findings with Bernstein’s work on the propagation of nerve impulses and nitrobenzene, which became a model trans-membrane potential led to great interest in bioelectricity compound for other investigators. and in the theory of nerve action in particular. It is noteworthy He also worked on the quinone- that Bernstein’s work was the last nail on animal electricity, hydroquinone transformation, which and came at a time when electricity was trying to rid itself of became the basis for Biilmann’s Fritz Haber the shadow of biology. quinhydrone electrode for measuring In 1910, (1868-1953) ______determined the charge on an electron by his famous oil *The first human electrocardiogram was recorded by Alexander Muirhead drop experiments. The following year, Frederick George (1848-1920), but it was Waller who did it in a clinico-physiological Donnan (1870-1956) established the conditions for setting. Moreover, Muirhead used a Thompson siphon recorder for his measurements while Waller used Lippmann’s capillary electrometer.

36 The Electrochemical Society Interface • Fall 2008 equilibrium between two electrolytic solutions separated Around this time, Alexander by a semi-permeable membrane. Today, Donnan’s name is Naumovich Frumkin (1895-1976), associated with both the nature of the equilibrium and the popularly known as the “father of potential across the membrane. electrochemistry in ,” made Around 1922, Prague evolved into vital contributions to our knowledge the “Mecca of electrochemistry.” On of the fundamentals of electrode February 10 of that year, Jaroslav reactions—particularly the influence of Heyrovsky (1890-1967), sometimes the electrode–electrolyte interface on called the “father of electroanalytical the rate of across it. chemistry,” recorded a current–voltage Based on his studies on the adsorption curve for a solution of of organic compounds on mercury, using a dropping mercury electrode and Frumkin proposed an adsorption ascribed the current jump between –1.9 isotherm that has come to be known and –2.0 V to the deposition of sodium as the Frumkin isotherm. He also ions on mercury. This marked the introduced the concept of potential Jaroslav Heyrovsky beginning of polarography, which took of zero charge. He joined hands with roots in his early work with F. G. Donnan on the electrode Veniamin Grigorevich Levich potential of aluminum, leading Heyrovsky into work on (1917-1987), an associate of theoretical liquid electrodes that provide a continuously renewable physicist Lev Davidovich Landau electrode surface. Later, he teamed up with Masuzo Shikata (1908-1968), in relating his experimental (1895-1964) and designed the first recording polarograph. In results to theory. The collaboration led 1959, Heyrovsky was awarded the Nobel Prize for his seminal to the development of the rotating disc electrode and to a quantitative analysis work on this electroanalytical technique. Polarography led Veniamin Grigorevich to a spurt in the growth of the theory of electrochemical Levich of the polarographic maximum. reactions and mass transport in electrolyte solutions, and laid Electric traction received a boost with the fundamentals of all voltammetric methods employed in the invention of the so-called Drumm electroanalysis. In 1929, Heyrovsky along with Emil Votocek traction battery. This was a nickel-zinc of the Prague Technical University, founded the journal, invented by James J. Collection of Czechoslovak Chemical Communications. Slovakian Drumm (1897-1974) and it became physical chemist and mathematical physicist Dionyz popular with its use in a suburban train Ilkovic (1907-1980), a research assistant to Heyrovsky, was in Ireland. In 1932, Francis Thomas one of the co-founders of polarography. The basic equation of Bacon (1904-1992) introduced the polarography, the Ilkovic equation, goes by his name. use of an alkaline electrolyte and Relationships between molecular structure and electrical inexpensive nickel electrode in fuel properties were also beginning to be unraveled. In 1923, cells. Twenty-seven years later, in Johannes Nicolaus Bronsted (1879-1947) in Denmark Thomas Percy Hoare 1959, he demonstrated a practical five- and Thomas (1874-1936) in kilowatt fuel cell. propounded, independently of each other, a theory on acids The quantitative measurement and bases. According to them, an acid was a compound with of electrochemical corrosion got a tendency to donate a proton (or hydrogen ion), while a established with a 1932 publication base was one that combined with a of Thomas Percy Hoare (1907- proton. The same year also witnessed 1978) and Ulick Richardson Evans Dutch-American physicist Petrus (1889-1980). Evans, the 1955 ECS Olin Josephus Wilhelmus Debye (1884- Palladium Award winner, described 1966) and German physicist and in the Biographical Memoirs of Fellows physical chemist Erich Armand of the Royal Society as the “father of Arthur Joseph Huckel (1896-1980) the modern science of corrosion elucidating fundamental theories and protection of metals,” laid the concerning the behavior of strong Ulick Evans foundations of the electrochemical electrolyte solutions. According to nature of corrosion. His 1937 book them, electrolyte solutions deviate Metallic Corrosion, Passivity, and Protection Petrus Debye from ideal behavior due to ion–ion is probably the most comprehensive attractions. They suggested that ions book ever written by a single author in solutions have a screening effect on corrosion science. In 1933, in a on the electric field from individual ions, which gave rise to paper on the oxygen electrode, Hoare the Debye length. Huckel is also famous for the Huckel rule showed how equilibrium potential for determining ring molecules and for the Huckel method could be determined from Tafel plots. of approximate molecular orbital calculations on π-electron Hoare was the first recipient of the U. systems. R. Evans award (1976) of the Institution Debye won the 1936 for his of Corrosion Science and Technology. contributions to molecular structure, for dipole moment Herbert H. Uhlig Herbert H. Uhlig (1907-1993) was relationships and for diffraction of X-rays and electrons in another champion of corrosion science. gases. In 1916, he showed that X-ray diffraction studies could He helped establish the ECS Corrosion be done with samples, eliminating in the process the Division. His Corrosion Handbook need to prepare good crystals. This has come to be known as published in 1948 continues to serve the Debye–Scherrer X-ray diffraction method. The originality generations of corrosion scientists and and extent of Debye’s contributions are reflected in the many engineers even half a century after its concepts that carry his name: the Debye–Scherrer method publication. of X-ray diffraction, Debye–Huckel theory, Debye theory of Described by F. Mansfeld as “an specific heat, Debye–Sears effect in transparent liquids, Debye under-appreciated giant in the world shielding distance, Debye temperature, Debye frequency, and of electrochemistry and corrosion,” the Debye theory of wave mechanics. He is also immortalized German electrochemist and materials scientist Carl Wagner (1901-1977) is by the CGS unit for dipole moment (debye), the Dipole Carl Wagner Moment monument in Maastricht, and the American also remembered as the “father of solid- Chemical Society award in his name. (continued on next page) The Electrochemical Society Interface • Fall 2008 37 years later in Apollo missions, which relied on fuel cells for in-flight power, heating, and drinking water (a product of the electrochemical reaction). It is interesting to note that Bacon ECS was the recipient of the first Grove medal in 1991. (continued fromClassics previous page) Second Half of the Twentieth state chemistry” for pioneering work in a variety of fields including tarnishing reactions, catalysis, , Century and Later fuel cells, semiconductors, and defect chemistry. Wagner formulated in 1943 the mechanism of ionic conduction in If thermodynamics of electrochemical systems doped zirconia, which laid the foundations for the field of solid dominated the first half of the twentieth century, kinetics state ionics. His contributions to corrosion were fundamental of electrochemical reactions began to be recognized as an to our understanding of the diffusion-limited growth of scales important branch of theoretical electrochemistry in the on metals at high temperatures as well as of other diverse second half. The credit for connecting electrochemical aspects such as local cell action, passivity, oxidation, thermodynamics and kinetics must go to English physical and cathodic protection. His other contributions include chemist John Alfred Valentine Butler (1899-1977). He, solid state coulometric , theoretical and experimental along with German surface chemist Max Volmer (1885- aspects of mixed ionic and electronic conduction, and the 1965), and Hungarian physical chemist Erdey-Gruz Tibor introduction of an interaction parameter to describe cross- (1902-1976), laid the seeds of the phenomenological basis thermodynamic effects in solutions. of electrochemical kinetics. The Butler–Volmer equation is a In 1937, Arne Wilhelm Kaurin Tiselius (1902-1971) product of their contribution to theoretical electrochemistry. turned another page in the history of electrochemistry People in Berlin are familiar with Max-Volmer Institute at the with his work on the moving boundary, which was later to Technical University of Berlin and the Max-Volmerstrasse. In become zone . He received the 1948 Nobel 1951, Butler teamed up with R. W. Gurney in introducing Prize for his work on electrophoresis for the separation the concept of energy levels in electrochemical calculations. of proteins and amino acids. In 1938 American electrical Butler’s contributions to are less well known, engineer Hendrik Wade Bode (1905-1982) made an especially his work on the kinetics of enzyme action. Electrode impact in electrochemistry through the Bode plot, which is kinetics also gained tremendously through the work of the used extensively in electrochemical impedance analysis of German electrochemist Klaus-Jürgen Vetter (1916-1974), electrochemical systems. who made path-breaking interpretations of the exchange By 1938, Belgian electrochemist and thermodynamicist current density, electrochemical reaction order, and the Flade Marcel Pourbaix (1904-1998) had constructed his famous potential. potential–pH diagrams, also called In the late 1950s, electroanalytical techniques came of Pourbaix diagrams. His work underpins age with the study of the hanging mercury drop electrode the importance of thermodynamics by Polish chemist Wiktor Kemula (1902-1985), whose in corrosion science, electrochemical seminal work in electroanalytical chemistry led to extensive refining, batteries, electrodeposition, investigations in polarography, amalgam electrochemistry, and electrocatalysis. In 1952 he founded stripping , , and electron the Commission of Electrochemistry transfer. Dutch physical and analytical chemist Izaak of the International Union of Pure Maurits Kolthoff (1927-1962), and Applied Chemistry, which in the popularly known as the “father of following year laid down the rules ” helped transform that govern the signs of electrode analytical chemistry from an art with Marcel Pourbaix potentials. empirical recipes to an independent Much of the theory behind cyclic scientific discipline. Among his voltammetry and electrochemical impedance contributions to electroanalytical came from the work of the English electrochemist John chemistry are conductometric Edward Brough Randles (1912-1998). His 1947 work on , potentiometric titrations, the cathode ray polarograph (oscillopolarograph) marked the potentiometric analysis, polarography beginning of linear sweep voltammetry, the solution to the for environmental trace metal analysis, peak current that comes through the famous Randles–Sevcik Izaak Kolthoff ion-selective electrodes, electron equation. (Sevcik was a Czech scientist, who along with transfer and precipitation reactions, Paul Delahay, developed several instruments with triangular and chemistry of nonaqueous media. He nurtured an edifice sweeps. As an aside, it must be mentioned that it was Delahay of analytical chemistry and a galaxy of students, which who in the 1950s introduced chronopotentiometry.) The same included such boldface names as James J. Lingane and year (1947) Randles published an analysis of an impedance Herbert A. Laitinen. The amalgamation of ideas and concepts circuit containing diffusion and interfacial electron transfer, from diverse areas such as thermodynamics, kinetics, which opened up a method to study fast electrode reactions. , electrochemistry, pH, and acid-base reactions Randles was not given to much publishing, but his papers lent that Kolthoff brought into analytical chemistry was of such remarkable insights into the mechanism of electrochemical import that Lingane once said, “...analytical chemistry has processes. The equivalent circuit used in the analysis is known never been served by a more original mind, nor a more as the Randles equivalent circuit, but in all fairness must be prolific pen, than Kolthoff’s.” termed the Randles–Ershler circuit, for Dolin and Ershler had Parallel developments were also happening in published similar results in the in 1940, which, electrochemical instrumentation, the most significant among however, were not easily available to the West due to the them probably being the invention of the by raging Second World War. the German engineer-physicist Hans Wenking (b. 1923). Enter British engineer . During his Basing the bulb , which he designed in 1952, as years at C. A. Parsons & Co., Ltd., an electrical company the core of his invention, Wenking made his contribution based in Newcastle-upon-Tyne, he became the first to develop to electrochemistry through the potentiostat. Until 1957, a practical hydrogen–air fuel cell and suggested its use in the were used at the Institute submarines. Unlike Grove’s cell, which used an acid electrolyte at Gottingen for corrosion studies. Later, Wenking along and solid electrodes, Bacon’s fuel cell had a less corrosive KOH with Gerhard Bank, began manufacture of the instrument. electrolyte and pressurized porous gas-diffusion electrodes. Potentiostats have come a long way in their circuitry, but The first practical application of his technology was to come the Wenking potentiostat remains a common trade name

38 The Electrochemical Society Interface • Fall 2008 and serves electrochemistry in myriad ways: corrosion Austrian inventor and electrochemist measurement, controlled electrolysis, and electrochemical Karl V. Kordesch (b. 1922) is a . familiar name to researchers in the As continued its area of batteries and fuel cells. He is contribution toward the growth the inventor of the alkaline primary of electrochemistry, there emerged cell (that has largely replaced the zinc– another great name: Heinz Gerischer carbon dry cells in flashlights) and the (1919-1994). The study of electro- key promoter of the RAM (rechargeable chemistry and photoelectrochemistry alkaline manganese dioxide) battery at semiconductor electrodes and the technology. In the 1960s, he became electrochemistry of excited states owe the first to develop the Apollo Fuel Cell, their origin to this genius. In 1960 and Karl V. Kordesch an with a circulating 1961, he made a detailed mathematical electrolyte. analysis of reactions at metal This was also the time when quantum electrochemistry Heinz Gerischer and semiconductor electrodes, by was taking roots with path-breaking investigations by which he showed that electron transfer Georgian scientist Revaz Dogonadze (1931-1985). He was across the electrode–electrolyte interface occurred through the first to recognize electron transfer processes as quantum tunneling. With a strong background in chemistry and mechanical transitions between two electronic states. His physics, he toyed with several concepts, many of which were research group was the first to suggest a quantum mechanical only beginning to be unraveled: the double-potential step (or model for proton transfer in polar solvents, which led to the a.c. modulation) to study very fast electrochemical reactions, formulation of a quantum mechanical theory of chemical, interfacial electrochemistry, single crystal electrodes, and low electrochemical, and biochemical processes in polar liquids. energy electron diffraction (which his assistant , But it was Rudolph Marcus (b. 1923), b. 1936, pursued), ultra-high vacuums, and time-resolved an American theoretical chemist, who spectroscopy. His work on electrode kinetics covered a lot of put quantum electrochemistry on the in the interpretation of the mechanisms of electrode map. He won the 1992 Nobel Prize in processes. For example, he introduced the potentiostatic Chemistry for his theory of electron transient technique for the study of reaction mechanisms. transfer in chemical systems. Scientific research in the just-independent India of Today electrochemistry looks the 1950s was considered more of an oddity of human set to shift gears with parallel endeavor than a profession. But that did not deter Indian advancements in materials science electrochemist Kadarundalige Sitharama Gururaja and characterization techniques. For Doss (1906-1989) pioneering a.c. effects on adsorption example, there is increasing thrust and electrode kinetics. He also introduced the techniques Rudolph Marcus toward exploiting nanoscopic materials of tensammetry (independently of Breyer) and the redoxo- and architectures. Expectations in kinetic effect, now termed faradaic rectification. The impact this direction are high because surface plays a key role in of these techniques in adsorp-tion electrochemical processes. Continual developments in the studies, kinetics of fast reactions, and synthesis and characterization of materials have also led to electroanalysis of trace metals is well welcome changes in electrochemical research. In closing, known. One of his illustrious pro- we have made a chronological sequence of noteworthy tégés, Sarukkai Krishnamachari developments in electrochemistry although this approach Rangarajan (1932-2008) was well might rob the interconnections between them. The scientists known for his unified approach to who are portrayed as pillars of electrochemistry here have modeling interfacial phenomena at either made seminal contributions or helped sprout what the macro, molecular, and electronic were previously only just suggestions. We do hope that our levels. list is comprehensive; undoubtedly there are inadvertent This period also saw arguably the omissions. For these we apologize in advance and would Sarukkai Krishnamachari finest collaboration between a student welcome comments. Rangarajan and a teacher in electrochemistry, featuring Brian Evans Conway (1927-2005) and John O’Mara Acknowledgments Bockris (b. 1923). They were instrumental in bringing electro- We thank Krishnan Rajeshwar for a critical reading of the chemistry from its moribund state manuscript and many helpful suggestions. of the Second World War era to modernity through their monumental multi-volume Modern Aspects of About the Authors Electrochemistry. Incidentally, another student of Bockris, the Indian Ashok K. Shukla is a professor in the Solid State and Structural electrochemist Amulya K. N. Reddy Chemistry Unit at the Indian Institute of Science, Bangalore. Brian Conway also helped bring electrochemistry His recent interest is in materials electrochemistry with to the fore by compiling Bockris’s emphasis on fuel cells, batteries, , and solid lectures into Modern Electrochemistry, ionics. He is also at the Central Electrochemical Research a two-volume book and arguably a Institute, Karaikudi. He may be reached at akshukla2006@ classic. Bockris and Conway were gmail.com. the trail-blazers of electrode kinetics in the western world. Conway was Thrivikraman Prem Kumar is at the Central Electrochemical a “complete” electrochemist in that Research Institute, Karaikudi. He received his PhD from the he worked on nearly all aspects of Indian Institute of Science, Bangalore (Supervisor: Professor electrochemistry: the electrified S. Sathyanarayana) in 1989. His research interests are in interface, ion , adsorption, lithium-based batteries and carbon nanostructures. He may electrode kinetics, oxide film formation, be reached at [email protected]. John O’Mara Bockris electrocatalysis, rechargeable batteries, and electrochemical .

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