Photoelectrochemical reduction of carbon dioxide in aqueous solutions on p-GaP electrodes: an a.c. impedance study with phase-sensitive detection

Abstract The mechanism of the photoelectrochemical reduction of water and CO2 on p-GaP electrodes in aqueous solutions was studied using photocurrent spectroscopy with chopped light excitation, revealing both a photo-anodic sub-bandgap response and a photo-cathodic current due to the bandgap response. A.c. power curves were recorded for p-GaP in pH 7 phosphate buffer electrolyte using modulated irradiation and a lock-in amplifier. At a light modulation frequency of 150 Hz, CO2 bubbling effected a 15% increase in the photo-cathodic current, relative to that in an Ar flushed solution. This effect disappeared at a light modulation frequency of 1560 Hz. Ruthenium pretreatment of p-GaP resulted in a doubling of both the cathodic photocurrent and the photovoltage. Pretreatment of p-GaP by dipping in a solution of CuSO4 caused a marked enhancement in both the dark current and photocurrent at reverse bias. In preparative reduction of aqueous bicarbonate, using light chopped at 22 Hz and −1.08 V between the p-GaP and a stainless steel counter electrode separated by a cation selective membrane, the production of formic acid was determined. The efficiency of conversion of the incident light energy to the Gibbs energy of formation of the formic acid produced amounted to 0.3%, both with bare and with Cu treated p-GaP.

[1]  D. Ginley,et al.  Chemically induced interface states in photoelectrochemical cells , 1983 .

[2]  P. Bartlett,et al.  The Photoelectrochemical Kinetics of p‐Type GaP , 1982 .

[3]  R. Memming.  Mechanism of the Electrochemical Reduction of Persulfates and Hydrogen Peroxide , 1969 .

[4]  D. Ginley,et al.  Interfacial Chemistry at p ‐ GaP Photoelectrodes , 1982 .

[5]  G. Nogami,et al.  Rotating Ring‐Disk Electrode Study on the Fixation Mechanism of Carbon Dioxide , 1995 .

[6]  L. Peter,et al.  Surface recombination at semiconductor electrodes: Part II. Photoinduced “near-surface” recombination centres in p-GaP , 1984 .

[7]  Kaname Ito,et al.  Photoelectrochemical reduction products of carbon dioxide at metal coated p-GaP photocathodes in aqueous electrolytes. , 1985 .

[8]  A. Heller,et al.  Some recent progress in semiconductor-liquid junction solar cells , 1980 .

[9]  Su-Moon Park,et al.  Thermodynamic stabilities of semiconductor electrodes , 1979 .

[10]  G. Horowitz.  Photocurrent onset potential and flatband potential of a p‐type GaP semiconducting photoelectrode , 1982 .

[11]  Hideo Tamura,et al.  Photoelectrochemical Reduction of Carbon Dioxide at p-Type Gallium Phosphide Electrodes in the Presence of Crown Ether , 1982 .

[12]  L. Peter,et al.  The reduction of oxygen at illuminated p-GaP: Evidence for a current doubling mechanism , 1985 .

[13]  B. Aurian‐Blajeni,et al.  Electrochemical reduction of carbon dioxide at elevated pressure on semiconductor electrodes in aqueous solution , 1994 .

[14]  M. Halmann,et al.  Photoelectrochemical reduction of aqueous carbon dioxide on p-type gallium phosphide in liquid junction solar cells , 1978, Nature.

[15]  A. Fujishima,et al.  Photoelectrocatalytic reduction of carbon dioxide in aqueous suspensions of semiconductor powders , 1979, Nature.

[16]  B. P. Sullivan,et al.  Electrochemical and electrocatalytic reactions of carbon dioxide , 1993 .

[17]  G. Horowitz.  Flatband potential of a p-type phosphide electrode , 1978 .

[18]  M. Aresta,et al.  Carbon Dioxide as a Source of Carbon : Biochemical and Chemical Uses , 1987 .

[19]  R. Tenne,et al.  Investigation into the photocurrent quadrature signal of photoelectrochemical cells , 1984 .

[20]  D. Ginley,et al.  P‐Type GaP as a Semiconducting Photoelectrode , 1980 .

[21]  E. L. Cook,et al.  Compilation of Energy Band Gaps in Elemental and Binary Compound Semiconductors and Insulators , 1973 .

[22]  G. W. Arnold,et al.  Photoelectrochemical Measurements of H‐ and He‐Implanted GaP , 1982 .

[23]  Y. Hori,et al.  Formation of hydrocarbons in the electrochemical reduction of carbon dioxide at a copper electrode in aqueous solution , 1990 .

[24]  R. Tenne.  Performance and stability of CdSe/polysulfide photoelectrochemical cells under chopped illumination , 1983 .

[25]  A. Tinnemans,et al.  On the electrolytic reduction of carbon dioxide at TiO2 and other titanates , 1983 .

[26]  Kaname Ito,et al.  On the reduction products of carbon dioxide at a p-type gallium phosphide photocathode in aqueous electrolytes. , 1984 .

[27]  M. Halmann.  Chemical Fixation of Carbon Dioxide: Methods for Recycling CO2 into Useful Products , 1993 .