Photo-driven Oxygen Vacancies Extends Charge Carrier Lifetime for Efficient Solar Water Splitting.

Abstract

Excessive surface oxygen vacancies would decrease the charge carrier lifetime and cause the serious recombination at the semiconductor/electrolyte interface. In this context, a photocharge/discharge strategy exposure to AM 1.5G sunlight is proposed to initiate the WO 3 photoelectrode and suppress the main charge recombination, which remarkably improves the photoelectrochemical (PEC) perormance. The photocharged WO 3 surrounded by a 8-10 nm overlayer and oxygen vacancies could be operated more than 25 cycles with 50 h durability without significant decay on PEC activity. Further heterojuncted with the CuO, the photocharged WO 3 /CuO photpanode exhibits an outstanding photocurrent of 3.2 mA cm -2 at 1.23 V RHE with a low onset potential of 0.6 V RHE , which is one of the best performance of p-n heterojunction structure. Importantly, using the nonadiabatic molecular dynamics combined with time-domain density functional theory, we clarify the prolonged charge carrier lifetime of photocharged WO 3 , as well as how electronic systems of photocharged WO 3 /CuO semiconductors enable the effective photoinduced electrons transfer from WO 3 into CuO. This work provides a feasible route to address excessive defects existed \xa0in photoelectrodes whilst without causing the extra recombination, further enhancing the carrier lifetime and boosting PEC water oxidation.