Hydrogen-substituted graphdiyne encapsulated cuprous oxide photocathode for efficient and stable photoelectrochemical water reduction.

Photoelectrochemical (PEC) water splitting is an appealing approach for "green" hydrogen generation. The natural p-type semiconductor of CuO is one of the most promising photocathode candidates for direct hydrogen generation. However, the CuO-based photocathodes still suffer severe self-photo-corrosion and fast surface electron-hole recombination issues. Herein, we propose a facile in-situ encapsulation strategy to protect CuO with hydrogen-substituted graphdiyne (HsGDY) and promote water reduction performance. The HsGDY encapsulated CuO nanowires (HsGDY@CuO NWs) photocathode demonstrates a high photocurrent density of -12.88 mA cm at 0 V versus the reversible hydrogen electrode under 1 sun illumination, approaching to the theoretical value of CuO. The HsGDY@CuO NWs photocathode as well as presents excellent stability and contributes an impressive hydrogen generation rate of 218.2 ± 11.3 μmol hcm, which value has been further magnified to 861.1 ± 24.8 μmol hcm under illumination of concentrated solar light. The in-situ encapsulation strategy opens an avenue for rational design photocathodes for efficient and stable PEC water reduction.