Internal electric field modulation by copper vacancy concentration of cuprous sulfide nanosheets for enhanced selective CO2 photoreduction

Although the internal electric field (IEF) of photocatalysts is acknowledged as a potent driving force for photocharge separation, modulating the IEF intensity to achieve enhanced photocatalytic performances remains a challenge. Herein, cuprous sulfide nanosheets with different Cu vacancy concentration were employed to study IEF modulation and corresponding direct charge transfer. Among the samples, Cu1.8S nanosheets possessed intensified IEF intensity compared with those of Cu2S and Cu1.95S nanosheets, suggesting that an enhanced IEF intensity could be achieved by introducing more Cu vacancies. This intensified IEF of Cu1.8S nanosheets induced numerous photogenerated electrons to migrate to its surface, and the dissociative electrons were then captured by Cu vacancies, resulting in efficient charge separation spatially. In addition, the Cu vacancies on Cu1.8S nanosheets accumulated electrons as active sites to lower the energy barrier of rate-determining step of CO2 photoreduction, leading to the selective conversion of CO2 to CO. Herein, the manipulation of IEF intensity through Cu vacancy concentration regulation of cuprous sulfide photocatalysts for efficient charge separation has been discussed, providing a scientific strategy to rationally improve photocatalytic performances for solar energy conversion.