Abstract
This research investigated the mechanisms associated with anodic wear of boron-doped diamond (BDD) film electrodes. Cyclic voltammetry (CV), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) were used to measure changes in electrode response and surface chemistry as a function of the charge passed and applied current density. Density functional theory (DFT) modeling was used to evaluate possible reaction mechanisms. The initial hydrogen-terminated surface was electrochemically oxidized at lower potentials than water oxidation (≤ 1.83 V/SHE), and was not catalyzed by the hydrogen-terminated surface. In the region where water oxidation produces hydroxyl radicals (OH), the hydrogen-terminated surface may also be oxidized by chemical reaction with OH. Oxygen atoms became incorporated into the surface via reaction of carbon atoms with OH, forming both C O and C-OH functional groups, that were also detected by XPS measurements. Experimental and DFT modeling results indicate that the oxygenated diamond surface lowers the potential for activationless water oxidation from 2.74 V/SHE for the hydrogen terminated surface to 2.29 V/SHE for the oxygenated surface. Electrode wear was accelerated at high current densities (i.e., 500 mA cm-2), where SEM results indicated oxidation of the BDD film resulted in significant surface roughening. These results are supported by EIS measurements that document an increase in the double-layer capacitance as a function of the charge passed. DFT simulations provide a possible mechanism that explains the observed diamond oxidation. DFT simulation results indicate that BDD edge sites (=CH2) can be converted to COOH functional groups, which are further oxidized via reactions with OH to form H 2CO3(aq.) with an activation energy of 58.9 kJ mol -1.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 122-131 |
| Number of pages | 10 |
| Journal | Electrochimica Acta |
| Volume | 89 |
| DOIs | |
| State | Published - Feb 1 2013 |
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Keywords
- Anodic corrosion
- Boron-doped diamond
- Density functional theory
- Ultrananocrystalline
ASJC Scopus subject areas
- Electrochemistry
- Chemical Engineering(all)
Cite this
Understanding anodic wear at boron doped diamond film electrodes. / Chaplin, Brian P.; Hubler, David K.; Farrell, James.
In: Electrochimica Acta, Vol. 89, 01.02.2013, p. 122-131.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Understanding anodic wear at boron doped diamond film electrodes
AU - Chaplin, Brian P.
AU - Hubler, David K.
AU - Farrell, James
PY - 2013/2/1
Y1 - 2013/2/1
N2 - This research investigated the mechanisms associated with anodic wear of boron-doped diamond (BDD) film electrodes. Cyclic voltammetry (CV), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) were used to measure changes in electrode response and surface chemistry as a function of the charge passed and applied current density. Density functional theory (DFT) modeling was used to evaluate possible reaction mechanisms. The initial hydrogen-terminated surface was electrochemically oxidized at lower potentials than water oxidation (≤ 1.83 V/SHE), and was not catalyzed by the hydrogen-terminated surface. In the region where water oxidation produces hydroxyl radicals (OH), the hydrogen-terminated surface may also be oxidized by chemical reaction with OH. Oxygen atoms became incorporated into the surface via reaction of carbon atoms with OH, forming both C O and C-OH functional groups, that were also detected by XPS measurements. Experimental and DFT modeling results indicate that the oxygenated diamond surface lowers the potential for activationless water oxidation from 2.74 V/SHE for the hydrogen terminated surface to 2.29 V/SHE for the oxygenated surface. Electrode wear was accelerated at high current densities (i.e., 500 mA cm-2), where SEM results indicated oxidation of the BDD film resulted in significant surface roughening. These results are supported by EIS measurements that document an increase in the double-layer capacitance as a function of the charge passed. DFT simulations provide a possible mechanism that explains the observed diamond oxidation. DFT simulation results indicate that BDD edge sites (=CH2) can be converted to COOH functional groups, which are further oxidized via reactions with OH to form H 2CO3(aq.) with an activation energy of 58.9 kJ mol -1.
AB - This research investigated the mechanisms associated with anodic wear of boron-doped diamond (BDD) film electrodes. Cyclic voltammetry (CV), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) were used to measure changes in electrode response and surface chemistry as a function of the charge passed and applied current density. Density functional theory (DFT) modeling was used to evaluate possible reaction mechanisms. The initial hydrogen-terminated surface was electrochemically oxidized at lower potentials than water oxidation (≤ 1.83 V/SHE), and was not catalyzed by the hydrogen-terminated surface. In the region where water oxidation produces hydroxyl radicals (OH), the hydrogen-terminated surface may also be oxidized by chemical reaction with OH. Oxygen atoms became incorporated into the surface via reaction of carbon atoms with OH, forming both C O and C-OH functional groups, that were also detected by XPS measurements. Experimental and DFT modeling results indicate that the oxygenated diamond surface lowers the potential for activationless water oxidation from 2.74 V/SHE for the hydrogen terminated surface to 2.29 V/SHE for the oxygenated surface. Electrode wear was accelerated at high current densities (i.e., 500 mA cm-2), where SEM results indicated oxidation of the BDD film resulted in significant surface roughening. These results are supported by EIS measurements that document an increase in the double-layer capacitance as a function of the charge passed. DFT simulations provide a possible mechanism that explains the observed diamond oxidation. DFT simulation results indicate that BDD edge sites (=CH2) can be converted to COOH functional groups, which are further oxidized via reactions with OH to form H 2CO3(aq.) with an activation energy of 58.9 kJ mol -1.
KW - Anodic corrosion
KW - Boron-doped diamond
KW - Density functional theory
KW - Ultrananocrystalline
UR - http://www.scopus.com/inward/record.url?scp=84871543499&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84871543499&partnerID=8YFLogxK
U2 - 10.1016/j.electacta.2012.10.166
DO - 10.1016/j.electacta.2012.10.166
M3 - Article
AN - SCOPUS:84871543499
VL - 89
SP - 122
EP - 131
JO - Electrochimica Acta
JF - Electrochimica Acta
SN - 0013-4686
ER -