Photoelectrochemical production of useful fuels from carbon dioxide on a polypyrrole-coated p-ZnTe photocathode under visible light irradiation

To achieve high performance photoelectrochemical CO2 reduction, a polypyrrole-coated p-ZnTe electrode (PPy/ZnTe) was fabricated as a new photocathode material and its catalytic activities were investigated. The PPy deposited on the p-ZnTe electrode improved the photoelectrochemical CO2 reduction activity as a surface modifying catalyst. Under the irradiation of visible light, the PPy/ZnTe showed a prominent performance with a 51.0% of Faradaic efficiency at -0.2 V (vs. RHE) without any significant overpotential loss. The ultraviolet photoelectron spectroscopy (UPS) and electrochemical impedance spectroscopy (EIS) implied that the enhanced catalytic performances were primarily attributed to the enhanced conversion efficiency of photoenergy on the PPy/ZnTe. It was suggested that the PPy/ZnTe electrode improved the generation of photo-induced electron-hole pairs, and the different work functions of ZnTe and PPy introduced an electron pathway from ZnTe to PPy and then to the reactants.