2021 NOBCChE National Conference September 18, 2021

TECHNICAL SESSIONS

Inorganic Chemistry/Physical Chemistry

11:15 AM - 12:15 PM Synthesis and Characterization of Luminescent Self-Assembled Materials for LED Applications. (19)

Adedayo Sanni, Graduate Student, Chemistry/Physical, Wayne State University There remains a need to develop facile synthetic approaches to form self-assembled hybrid organic- inorganic nanostructures and enable solution processed lighting technologies. To help enable this technological transformation, we develop a layered, synthetic approach, which allows us to synthesize various analogues of self-assembled Pb-halide perovskites. This synthetic approach allows us to control the appearance of narrowband or broadband luminescence in the light emission spectra of these materials. X-ray difraction and electron microscopy reveal that the more granular material morphologies correlate with the appearance of broadband features in the spectra of light emitted below the exciton gap of materials formed under high amine concentrations. Photoelectron studies revealed that these materials are similar in composition and possess identical bonding in the bulk. Power-dependent photoluminescence (PL) studies revealed the emission stems from defect sites that can act as electron donors or acceptors. We propose iodide vacancy defect mediated exciton trapping gives rise to the broadband PL we observe in these materials. We extend our synthetic approach to layered hybrid double perovskites containing more environmentally benign metals such as Bi and Ag to replace Pb in the Pb- halide perovskites. In conclusion, our layered synthetic approach provides an avenue to synthesize various emergent luminescent self-assembled materials which could be useful in lighting applications.

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Technical Sessions Inorganic/Physical Chemistry 1 2021 NOBCChE National Conference September 18, 2021

Mechanistic insights enabling homogenous phase formation of multimetallic metal phosphide nanoparticles (39)

Ms. Tepora Su'a, Graduate Student, Chemistry, Wayne State University Transition metal phosphide (TMP) nanoparticles have gained tremendous attention within the last decade due to their unique magnetic and catalytic properties. To this end, the synthesis of monometallic (M2P; M = Fe, Co, Ni) TMP nanomaterials have been extensively studied, however establishing colloidal synthetic routes to prepare complex TMP phases remains a challenge. In order to gain mechanistic insights into homogeneous phase formation of bimetallic (M2-xM’xP; M, M’ = Fe, Co, Ni) TMP systems the phosphidation rates of monometallic TMP phases with respect to temperature and time were evaluated in this study. The relative reactivity of metal carbonyl and metal acetylacetonate salt precursors with phosphorus was used to rationalize the synthetic pathways necessary to form bimetallic TMP phases and develop streamlined routes to new trimetallic TMP phases such as Fe2-x-yNixCoyP.

Key Words: transtion metal phosphide, nanoparticle, nanomaterial

Semiconducting Oxide Materials to Catalyze the Oxygen-Evolution and Chlorine-Evolution Reactions (38)

Dr. Bart Bartlett, Professor, Department of Chemistry, University of Michigan Tungsten(VI) oxide (WO3) remains prominent in photoelectrochemical approaches toward the oxygen evolution reaction (OER) from water because of its stability in acidic solution (desirable for its redox partner, the hydrogen evolution reaction). WO3 electrodes were synthesized by spin-coating an ammonium metatungstate sol. Photochromic HxWO3 generated at low concentration during the synthesis leads to an increase the donor density, and depositing an FeOOH electrocatalyst increases the selectivity for the OER.

Moreover, fast oxidation reactions such as chloride oxidation and sulfte oxidation show very stable photocurrent density on HxWO3 photoelectrodes as well as Co3O4 spinel dark electrodes, hinting that other redox partners for hydrogen evolution under acidic conditions are plausible.

Key Words: Solar Energy, Catalysis, Semiconductors

12:15 PM - 1:15 PM

Effect of dissimilar donor/acceptor ligands in metallosurfactants in the modulation of the HOMO-LUMO energy gap required for molecular rectification (68)

Technical Sessions Inorganic/Physical Chemistry 2 2021 NOBCChE National Conference September 18, 2021

Mrs. Samudra Amunugama, Graduate Research Assistant, Chemistry, Wayne State University Molecular rectifers are complementary to solid state diodes which allows directional electron transport. This behavior is important in converting alternating current into direct current. Our approach is to develop metallosurfactants which can be used as molecular rectifers. We use Langmuir-Blodgett method to deposit well-ordered monolayers of these complexes onto solid substrates and prepare nanoscale devices to analyze the electron transfer properties. For a molecule to act as a rectifer, the frontier molecular orbital energy of the molecule should have comparable energy with the Fermi energy level of the electrode. Therefore, we hypothesize that by introducing electron donor and electron acceptor type substituents into the opposite ends of the molecule will allow us to modulate HOMO-LUMO energy gap, enabling molecular rectifcation. This research project describes the synthesis and characterization of asymmetric terpyridine based Ru(II) complexes which contain octadecyloxy benzene as the donor group and substituted phenanthroline/terpyridine group as the acceptor group. The cyclic voltammetry data of [(terpyD)RuII(terpyA)]2+ and [(terpyD)RuII(phenA)Cl]2+ surfactants indicate that Ru(II)/Ru(III) occur at ca. 0.86-0.87 V and 0.4-0.3 V respectively. The complexes with electron withdrawing nitro groups shows considerably lower reduction potentials at ca.-1.0 and-1.3 V due to nitro group reduction. However, complexes with unsubstituted phenanthroline and terpyridine ligands show higher reduction potentials at ca. -1.6 and -2.4 V. These redox properties indicate that the HOMO/LUMO energy levels of these complexes can be varied by changing the nature of the electron accepting substituent in the ligand framework. Langmuir-Blodgett studies demonstrate that these complexes form ordered, stable monolayers at the air/water interface. Preliminary Current-voltage studies show that [(terpyD)RuII(phenNO2)Cl]2+ complex acts as a rectifer with a good rectifcation ratio. This research work allows us to study a new class of asymmetric molecular rectifer that depends on donor/acceptor ligands to obtain directional electron transport.

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Investigation of electron transport of photosensitive ruthenium-based amphiphiles for rectification (72)

Abigail Cousino, GRA, Chemistry, Wayne State University Unidirectional electron transport refers to the diode-like property of directional electron conductance. In electrical circuitry, this property is referred to as a “rectifer,” which functions to allow electrons to fow from point A to point B while preventing reversibility, allowing the conversion of an alternating current (AC) into a direct current (DC) and is required for any computational process. The development of photo responsive materials would help improve the feld of optoelectronics and micellar luminescence. Our group has successfully developed several ruthenium-based complexes. Using these previously developed methods, due to its excellent photosensitive properties, we have developed a ruthenium bipyridine complex coordinated to bidentate amphiphilic phenol-head groups. We will investigate the electrochemical properties of these systems to evaluate the redox processes, the optical and electronic

Technical Sessions Inorganic/Physical Chemistry 3 2021 NOBCChE National Conference September 18, 2021 properties to assess the photostability and emission of these complexes. These [Ru(bpy)2(LPh)]Cl complexes will be deposited on the surface of water to form an ordered flm using the Langmuir-Blodgett methodology. These flms will then be deposited on gold electrodes have their redox and amphiphilic properties tested evaluated for rectifcation and photo response.

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In-Situ/Operando Characterization of Titanium Nitride MXenes for Water Splitting (85)

Mr. Ekene Uwadiunor, Masters Student, Chemical Engineering, Texas A&M University: The Djire Lab The production of hydrogen fuel from water splitting through the hydrogen evolution reaction (HER) has been investigated for more than a century; yet, there exists no commercial water splitting device because of the lack of an efcient electrocatalyst. The benchmark electrocatalyst for HER is Pt/C; however, its scarcity and high price limit its large-scale utilization. Consequently, great promise has been demonstrated in a new class of two-dimensional (2) materials called MXenes due to a low HER overpotential. In this presentation, I will report on the electrocatalytic performance of MXenes and show that these electrocatalysts are active for HER electrocatalysis. These 2D electrocatalysts possess properties that are desirable for a broad range of electrocatalytic applications. These properties include high electronic conductivity, high surface area and hydrophilicity, heterogeneity of redox-active transition metals, and tunable surface functionalities. More specifcally, I will show the report on the detailed mechanisms of HER electrocatalysis on 2D titanium nitride MXenes using in-situ/operando spectroelectrochemical characterization techniques including Raman, Fourier-transform infrared, and ultra-violet visible spectroscopies. Moreover, these techniques allow for real-time monitorization of the material under operating conditions. The results from the in-situ/operando analyses revealed that the activity of HER on titanium nitride MXenes is infuenced by the basal plane defect sites, surface termination groups, and the elemental compositions of the MXene structures. Compared to the more popular carbide MXenes, nitride MXenes feature metal–nitrogen bonds that are expected to impart unique electronic and structural characteristics for electrocatalysis. Lastly, I will show synthesis-structure- performance relationships derived from the in-situ/operando spectroelectrochemical analyses that can be used to predict the performance of future electrocatalysts for HER and related electrocatalytic reactions.

Key Words: 2D MXene, electrochemistry, hydrogen evolution reaction, spectroelectrochemical characterization.

Technical Sessions Inorganic/Physical Chemistry 4 2021 NOBCChE National Conference September 18, 2021

Laser studies in the laboratory of the atoms and radicals observed in comets

Dr. Wiliam M. Jackson, Chemistry, University of California, Davis Comets were formed before the planets in our solar system so that they provide clues to the chemical origin. My collaborators and I have designed laboratory lasers studies to demonstrate how the CN, C2, C3, CS, C, O, S, and S2, that I and others have seen in comets with the ground and satellite-based telescopes can be formed. These species are very reactive and to study them in the laboratory they must be formed in situ. A low-powered vacuum ultraviolet (VUV) fash lamp, focused excimer laser and an unfocused tunable VUV laser have all been employed to accomplish this. They are identifed by using a separate tunable dye laser to either excite them so they will fuoresce or ionize them. In the latter case, the ions formed are separated and identifed with a time-of-fight (time-of- fight mass spectrometer (TOF-MS). With these tools, we have been able to explain how some of them are formed in the atmospheres of comets or other astronomical environments. These results of the studies have demonstrated not only how they are formed but also provided the necessary information for key facts about the chemical evolution of the early Earth’s atmosphere as well as key data for calculating the temperature of the cosmic background radiation.

Acknowledgments: The author gratefully acknowledges the support of NSF, NASA, ONR, and DOE over his career.

Key Words: comets, lasers, astronomy

Technical Sessions Inorganic/Physical Chemistry 5