Photocorrosion behavior of Cu2O nanowires during photoelectrochemical CO2 reduction

Abstract

• The corrosion behavior of Cu 2 O nanowires during PEC CO 2 reduction is unraveled. • Self-reduction of Cu 2 O by photoelectrons is the dominant photocorrosion pathway. • The photocorrosion modes is alleviated by tailoring the conditions of electrolyte. Cuprous oxide (Cu 2 O) is a promising photocathode candidate for photoelectrochemical (PEC) CO 2 reduction reaction (CO 2 RR) 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, Cu 2 O nanowires film was used as a model photocathode to explore the corrosion behavior during PEC CO 2 RR. The evolution of Cu 2 O 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 Cu 2 O under illumination. Assisted with the measurement in the existence of electron and hole scavengers, the self-reduction of Cu 2 O by the accumulation of photoelectrons is considered as the primary corrosion pathway for Cu 2 O photocathode in aqueous solution.