Anion Adsorption, CO Oxidation, and Oxygen Reduction Reaction on a Au(100) Surface: The pH Effect

The effects of pH on the surface reconstruction of Au(100), on CO oxidation, and on the oxygen reduction reaction (ORR) have been studied by a combination of surface X-ray scattering (SXS), Fourier transform infrared (FTIR) spectroscopy, and rotating ring-disk electrode (RRDE) measurements. In harmony with previous SXS and scanning tunneling microscopy (STM) results, the potential-induced hexagonal (“hex”) to (1 × 1) transition occurs faster in an alkaline electrolyte than in acidic media. In alkaline solution, CO adsorption facilitates the formation of a “hex” phase; in acid solution, however, CO has negligible effect on the potential range of thermodynamic stability of the “hex” ↔ (1 × 1) transition. We propose that in KOH the continuous removal of OHad in the Langmuir−Hinshelwood reaction (CO + OH = CO2 + H+ + e-) may stabilize the “hex” phase over a much wider potential range than in CO-free solution. In acid solution, where specifically adsorbing anions cannot be displaced by CO from the Au(100) surface, CO has negligible effect on the equilibrium potential for the “hex” ↔ (1 × 1) transition. Such a mechanism is in agreement with the pH-dependent oxidation of CO. The ORR is also affected by the pH of solution. It is proposed that the pH-dependent kinetics of the ORR on Au(100) can be unraveled by finding the relationship between kinetic rates and two terms:  (i) the energetic term of the Au(100)−O2- interaction determines the potential regions where the rate-determining step O2 + e = O2- occurs, and (ii) the preexponential term determines the availability of active sites for the adsorption of O2-.     «

The effects of pH on the surface reconstruction of Au(100), on CO oxidation, and on the oxygen reduction reaction (ORR) have been studied by a combination of surface X-ray scattering (SXS), Fourier transform infrared (FTIR) spectroscopy, and rotating ring-disk electrode (RRDE) measurements. In harmony with previous SXS and scanning tunneling microscopy (STM) results, the potential-induced hexagonal (“hex”) to (1 × 1) transition occurs faster in an alkaline electrolyte than in acidic media. In al...     »

pH (effect on surface reconstruction of Au(100) electrode and Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode) Surface phase transition (of Au(100) electrode and effect of CO oxidn.) Cyclic voltammetry (of Au(100) electrode in KOH and in HClO4 solns. and pH effect on Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode) Oxidation (of CO an gold and pH effect on surface reconstruction of Au(100) electrode and Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode) Reduction (of oxygen on gold and pH effect on surface reconstruction of Au(100) electrode and Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode) Interfacial structure (reconstructed pH effect on surface reconstruction of Au(100) electrode and Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode) anion adsorption carbon monoxide electrooxidn oxygen electroredn gold surface surface reconstruction gold electrode pH effect     «

pH (effect on surface reconstruction of Au(100) electrode and Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode) Surface phase transition (of Au(100) electrode and effect of CO oxidn.) Cyclic voltammetry (of Au(100) electrode in KOH and in HClO4 solns. and pH effect on Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode) Oxidation (of CO an gold and pH effect on surface reconstruction of Au(100) electrode and Cl- and ClO4- adsorpt...     »

CAN 140:135386 72-2 Electrochemistry Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, USA. Journal 1520-6106 7440-57-5 (Gold) Role: DEV (Device component use), PEP (Physical, engineering or chemical process), PRP (Properties), PYP (Physical process), PROC (Process), USES (Uses) (pH effect on surface reconstruction of Au(100) electrode and Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode); 14797-73-0 (Perchlorate); 16887-00-6 (Chloride) Role: PEP (Physical, engineering or chemical process), PRP (Properties), PYP (Physical process), PROC (Process) (pH effect on surface reconstruction of Au(100) electrode and Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode); 630-08-0 (Carbon monoxide); 7782-44-7 (Oxygen) Role: PRP (Properties), RCT (Reactant), RACT (Reactant or reagent) (pH effect on surface reconstruction of Au(100) electrode and Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode); 1310-58-3 (Potassium hydroxide); 7601-90-3 (Perchloric acid) Role: NUU (Other use, unclassified), PRP (Properties), USES (Uses) (surface reconstruction of Au(100) electrode in KOH and in HClO4 solns. and pH effect on Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode)     «

CAN 140:135386 72-2 Electrochemistry Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, USA. Journal 1520-6106 7440-57-5 (Gold) Role: DEV (Device component use), PEP (Physical, engineering or chemical process), PRP (Properties), PYP (Physical process), PROC (Process), USES (Uses) (pH effect on surface reconstruction of Au(100) electrode and Cl- and ClO4- adsorption, CO oxidn., and oxygen redn. reaction on Au(100) electrode); 14797-73-0 (P...     »