Photocorrosion behavior of Cu2O nanowires during photoelectrochemical CO2 reduction

Cuprous oxide (Cu2O) is a promising photocathode candidate for photoelectrochemical (PEC) CO2 reduction reaction (CO2RR) due to its narrow band gap and suitable band alignment. However, it suffers from severe photocorrosion, and the real reason is confused. In this work, Cu2O nanowires film was used as a model photocathode to explore the corrosion behavior during PEC CO2RR. The evolution of Cu2O photoelectrodes was monitored by microscopy techniques (scanning electron microscope, transmission electron microscope) and compositional analyses (X-ray diffraction, X-ray photoelectron spectroscopy), more content of Cu was detected after testing under illumination than that in the dark. Polarization curves also show a much higher corrosion current of Cu2O under illumination. Assisted with the measurement in the existence of electron and hole scavengers, the self-reduction of Cu2O by the accumulation of photoelectrons is considered as the primary corrosion pathway for Cu2O photocathode in aqueous solution.