Defect engineering of TiO2 protected Cu2O photocathode via electron beam annealing for selective photoelectrochemical CO2 reduction to methanol

초록

Electron beam annealing (EBA) treatment was applied to TiO2 overlayered Cu2O (TiO2/Cu2O) photocathodes to control oxygen vacancy (Ov) concentrations of TiO2 overlayer for photoelectrochemical (PEC) CO2 reduction-tomethanol selectivity of Cu2O photocathodes. The EBA-treated TiO2/Cu2O photocathodes exhibited a significantly boosted faradaic efficiency for the methanol production, yielding approximately a 10-fold improvement over the untreated TiO2/Cu2O photocathodes. It was mainly due to the increment of Ov concentration of TiO2 overlayer via the EBA treatment, confirmed by three analyses: X-ray photoelectron spectroscopy, electron spin resonance, and Raman spectroscopy. The increased Ov on the surface of TiO2 overlayer provides more active sites for CO2 adsorption to the surface of Cu2O photocathodes, thereby improving the PEC CO2 reduction to methanol selectivity of Cu2O photocathodes. This work highlights the critical role of defect engineering in optimizing the interface of photocathodes for the efficient PEC CO2 reduction to the value-added chemicals.

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