Electrochemical Sensing with the Pseudo-Graphite, GUITAR Graphene from the University of Idaho Thermolyzed Asphalt Reaction I. Francis Cheng, University of Idaho [email protected] 01/26/2018 University of Idaho - [email protected] – 49th SWAP 1 An Ideal Electrode Widest Possible Electrochemical Window - + Potential n+ H Gassing: 2H O + 2e- H + 2OH- Corrosion: M M + ne- 2 2 2 + - O2 Gassing: 2H2O O2 + 4H + 4e - e- Ox Fast Heterogeneous + e- Electron Transfer Red 01/26/2018 2 GUITAR Discovery in 2009 • 2008 - Residue from Workup of Oil Shale Analysis • Optical and Scanning Electron Microscopies • Clear Basal and Edge Plane Geometries • X-Ray Photoelectron Spectroscopy • Almost Pure sp2 carbon (2017 reinterpretation) 01/26/2018 University of Idaho - [email protected] – 49th SWAP 3 Basal/Edge Planes SEM -seem identical GUITAR HOPG GUITAR What Is It? • Evidence that is a Nanocrystalline (Disordered) Graphite • Raman Spectroscopy • X-ray Photoelectron Spectroscopy • Solid-State NMR • Thermogravimetric Analysis • Not a Graphite – Not Observed In Scientific Literature – Pseudo Graphite • Atomic Forces Microscopy • Electrochemistry 01/26/2018 University of Idaho - [email protected] – 49th SWAP 5 Raman Studies • 2009 only with 532 nm D and G band indicate nano-crystalline graphite. • 2016 Study Boise State University - 633, 532, 514, 488 and 442 nm D-Band 1300 – 1400 cm-1 G-Band • Defective Graphites 1575 – 1600 cm-1 G’ or 2D Band – 2nd Harmonic of D-Band 2400-2800 cm-1 01/26/2018 University of Idaho - [email protected] – 49th SWAP 6 Raman 633 nm Laser Excitation for GUITAR 532 nm 442 nm 663 nm D G 2D or G’ D-Band = 1347 nm, I = 400 G band = 1583 nm, I = 375 01/26/2018 University of Idaho - [email protected] – 49th SWAP 7 Elaser (eV) Slope Graphite (cm-1/ev) GUITAR Literature D 53 50 G 4 10 2D 117 100 Crystal Grain Size, La From Raman I(D)/I(G) @514 nm • Empirical Relationship – A.C. Ferrari, Solid State Comm. 2007, 143, 47-57 퐼(퐷) • GUITAR = 1.2 퐼(퐺) • La = 1.5 nm or 3.5 nm 01/26/2018 University of Idaho - [email protected] – 49th SWAP 9 Raman Summary • Resembles nano-crystalline graphite • G-Band • D-Band • Crystal size (La) of 1.5 nm to 3.5 nm • XRD studies underway 01/26/2018 University of Idaho - [email protected] – 49th SWAP 10 - Pure sp2-C appears around 120-140 ppm - Pure sp3-C appears around 20-60 ppm - GUITAR shows a broad peak around 105 ppm (similar to polycrystalline graphite) Adamantane 2 3 - The ratio of sp /sp in GUITAR is not solvable C H by SS-NMR 10 16 ppm GUITAR HOPG (ZYA) Fig. 16. NMR spectra of carbon films Materials Chemistry and Physics 96 (2006) 253–277 http://www6.cityu.edu.hk/appkchu/publications/2006/06.20.pdf01/26/2018 University of Idaho - [email protected] – 49th SWAP ppm 11 Feb 10, 2017 by Kabir Peak Analysis Data Set:[Book1]Sheet1!intensity Date:5/16/2017 BaseLine:Shirley XPS Peak AssignmentChi^2=4.47059E+003 Adj. R-Square=9.98587E-001 # of Data Points=601. SS=2.65553E+006 Degree of Freedom=594. 800 C 1s Pristine GUITAR 700 284.2 eV, (C=C), 81.6% 600 285.4 eV, (C-C), 14.3% 286.9 eV, (C=C, C-O) 4.1% 500 400 Intensity 300 200 Wide-scan indicates only C 100 0 0 500 1000 1500 280 282 284 286 288 290 292 -100 Binding Energy(eV) 01/26/2018 University of Idaho - [email protected] – 49th SWAP 12 Peak IndexPeak Type Area Intg FWHM Max Height Center Grvty Area IntgP 1. Gaussian 9928.517 1.54524 6036.0973 284.1674 81.6035 2. Gaussian 1745.67166 1.54524 1061.29083 285.39601 14.34785 3. Gaussian 492.59029 1.54524 299.47301 286.93406 4.04865 Elemental Analysis 2016 ALS Laboratories – Tucson AZ Mass Percentage Mole Fraction Carbon 96.8 0.846 Hydrogen 1.3 0.134 Nitrogen <0.05 -- Oxygen 3.08 0.0202 Sulfur <0.2 -- 01/26/2018 University of Idaho - [email protected] – 49th SWAP 13 Based on XPS and Elemental Analysis 01/26/2018 University of Idaho - [email protected] – 49th SWAP 14 TGA Decomposition Indicates that GUITAR behaves like a Graphite 100% Under Air HOPG flake 90% HOPG Podwer GUITAR flake Onset of Mass Percentage 80% Decomposition 10% Temperature (°C) 0% 0 200 400 600 800 1000 01/26/2018 University of Idaho - [email protected] – 49th SWAP 15 900 MWNT Diamond HOPG [6,8] [8,9] 800 [TW,1] Graphite Decomposition Onset Temperature (°C) 700 GUITAR [4,8,9] [TW] Onion like • First Derivative Method carbon [10] 600 • GUITAR Td is in the graphite region Fullerene [5,8] SWNT [2,3] 500 400 Amorphous Carbon 300 [2,7] 200 What is GUITAR? Graphite Not a Graphite • Nanocrystalline Graphite • AFM • Layered Morphology • Electrochemistry • Raman Analyses • Resistance to Corrosion • Solid State – NMR • Fast HET • faster than • Elemental Analysis • Graphites, BDD, DLC, a-C’s • Thermogravimetric Analysis 01/26/2018 University of Idaho - [email protected] – 49th SWAP 17 GUITAR – Lacks Step Defects -- Wavy surface 30 nm amplitude GUITAR +/- 15 nm HOPG +/- 1 nm 01/26/2018 University of Idaho - [email protected] – 49th SWAP 18 Heterogeneous E.T. GUITAR Electrodes 4-/3- 1) GUITAR - Fast Electron Transfer at Basal Plane Fe(CN)6 • Cyclic Voltammetry with GUITAR k0 10-2 cm/s >> 10-6 cm/s Graphites/Graphenes -2 2) GUITAR – No Anisotropy ET ** EPrate = BPrate = 10 cm/s ** Ox Red Ox Red slow Fast Graphite GUITAR Ox Ox Fast Fast Red Red 01/26/2018 University of Idaho - [email protected] – 49th SWAP 19 Better Performance Villareal, Claudia and co-workers, “Carbon allotropes as sensors for environmental monitoring”, Current Opinion in Electrochemistry, 2017, 3, 106-113. HET Rates for 3- - 4- Fe(CN)6 + e ⇄ Fe(CN)6 01/26/2018 University of Idaho - [email protected] – 49th SWAP 20 Crystalline Basal Planes – Slow HET rates GUITAR – Fast HET Rates Disordered Basal Planes -Waviness? McCreery, Anal. Chem. 1992, 64, 2518-2524 01/26/2018 University of Idaho - [email protected] – 49th SWAP 21 Resistance to Corrosion and H2 Overpotential 1) High Resistance to Corrosion • GUITAR = Boron Doped Diamonds, DLC & a-C • Remember that GUITAR has much faster e- transfer rates than other allotropes 2) High Hydrogen Overpotential & Electrochemical Potential Window • 3 V in 1 M H2SO4 vs. 2 V for graphites 01/26/2018 University of Idaho - [email protected] – 49th SWAP 22 GUITAR - Best Combination • Corrosion Resistance • Heterogeneous e- Transfer. Tafel Analyses 2 0 4-/3- Log Icorr (A/cm ) Log k Fe(CN)6 (cm/s) Basal Plane (BP) GUITAR -9 -2 BP-Graphites/Graphenes -3 to -7 -3 to -9 Boron Doped Diamond -8 to -9 -3 to -5 Literature Diamond-Like Carbon & -4 to -9 -4 to -5 Amorphous Carbons 01/26/2018 University of Idaho - [email protected] – 49th SWAP 23 Pt Pd BDD Graphene Graphite Foil Graphite Rod 3 M NaCl GUITAR Ti CNT Pt DLC Graphite BDD Graphite Foil 1 M H2SO4 Graphite Rod GUITAR Pd Pt Cu 0.5 M Na SO Graphene 2 4 Graphite BDD Graphite Foil Graphite Rod GUITAR 1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 2 01/26/2018 Corrosion Current (A/cm ) 24 3.5 V, 0.10 M Na2SO4 3.0 V, 1 M H SO GUITAR 2 4 3.1 V, 0.6 M NaCl BPPG, Graphite Rod 1.8V, 1M H2SO4 Reduction Corrosion Of And Water Water 1.6 to 3 V, H2SO4 Boron Doped Diamond Oxidation 3 to 3.4 V, H SO Diamond-like Carbon 2 4 2.7 to 3.4 V, H SO Amorphous Carbon 2 4 -1.0 V 0.0 V +1.0 V +2.0 V Potential vs. NHE 01/26/2018 University of Idaho - [email protected] – 49th SWAP 25 Blister formation on graphitic anodes + - HSO4 CO2(g) + O2(g) - ⇄ HSO4 Step Defects, Grain Boundaries & Edge Planes - HSO4 • CV sweeps -- Electrolyte inter- and de-intercalation - + - - – [Cx] + [HSO4 ] + y H2O ⇄ [Cx HSO4 ]y(H2O) + e Murray et al, Analytical Chemistry, 1995, 67, 2201-2206 01/26/2018 University of Idaho - [email protected] – 49th SWAP 26 - HSO4 Graphite -Intercalation -Edge Plane -Basal Plane GUITAR - -No Intercalation HSO4 - HSO4 No Intercalation No Intercalation 01/26/2018 University of Idaho - [email protected] – 49th SWAP 27 - Current Models HSO4 No Intercalation Observations: No Intercalation Also – lack of clean mechanical exfoliation Seamless but disordered B.P. Disordered B.P. sp3 links? Model: Cross-linked planes prevent intercalation, Inter-plane Defects 01/26/2018 University of Idaho - [email protected] – 49th SWAP 28 An Ideal Electrode Widest Possible Electrochemical Window - + Potential n+ H Gassing: 2H O + 2e- H + 2OH- Corrosion: M M + ne- 2 2 2 + - O2 Gassing: 2H2O O2 + 4H + 4e - e- Ox Fast Heterogeneous + e- Electron Transfer Red 01/26/2018 29 Conclusions •GUITAR has not been observed in the scientific literature. •It is a newly discovered allotrope of carbon •New chemical and physical features • Next studies – Physical Differences •Pseudo-Graphite • Appearance of Graphite but with different chemical characteristics 01/26/2018 University of Idaho - [email protected] – 49th SWAP 30 Applications • Best Combination of e- transfer and resistance to corrosion • Nanostructures • Sensors • Water Purification • Fuel Cells 01/26/2018 University of Idaho - [email protected] – 49th SWAP 31 CV’s of dopamine +2.2 V vs Ag/AgCl, 5 minutes in 0.1 M PBS (pH 7.2) 01/26/2018 University of Idaho - [email protected] – 49th SWAP 32 Acknowledgements • Funding ABB Group University of Idaho Yuwei Kan(XRD), Nolan Nicholas, Armando McDonald, Eric Aston Graduate Students: Simon McAllister, Yuqun Xie, Isaiah Gyan, Jeremy Foutch, Haoyu Zhu, Humayun Kabir, Charles Nwamba Undergrads: Ricardo Lopez, Peng Ma, Hailey Smith Oklahoma State: Dave McIlroy and group (XPS) Boise State University: David Estrada, Paul Davis, Kari Livingston, Kati M.