Photoelectrochemical Reduction of Carbon Dioxide to Methanol on a ZnTe Electrode Modified with a N-Doped Carbon Thin Layer

Photoelectrochemical CO2 reduction offers a promising pathway for solar-driven methanol production. ZnTe is a promising material for deep reduction reactions due to its favorable conduction band position and bandgap; however, its efficiency is severely limited by surface defect-induced charge recombination. Here, we show for the first time the efficient generation of methanol from the photoelectrochemical reduction of CO2 on ZnTe electrodes modified by a N-doped carbon thin layer. This modification simultaneously passivates detrimental surface states and functions as an active cocatalyst. Under AM 1.5G illumination, the photocathode achieves a current density of 2.1 mA cm–2 at −0.2 V vs RHE in CO2-saturated electrolyte, with a 51% Faradaic efficiency for methanol. Furthermore, a solar-to-methanol conversion efficiency of 0.22% is achieved in a tandem PEC device for unassisted CO2 conversion, employing a BiVO4 photoanode and a perovskite solar cell under one sun AM 1.5G illumination.