Nitrogen-doped 3D micro-coral Cd(O,S) for highly efficient zero-VRHE solar-to-hydrogen photocathode

Abstract

Solar-light-driven hydrogen (H2) production is considered one of the most promising methods for clean energy generation to replace fossil fuel-based energy. Herein, we report a highly efficient 3D coral-like N-doped cadmium oxysulfide (Cd(O,S)) photocathode for hydrogen evolution reaction (HER) in an alkaline solution. The N5Cd(O,S) with a certain nitrogen amount achieved an onset potential of 0.63 VRHE with a photocurrent density of 0.74 mAˑcm−2 at 0 VRHE and solar-to-hydrogen efficiency (ηSTH) of 6.6 %. In a practical application, the amount of evolved H2 by N5Cd(O,S) photocathode was 12.3 μmol·cm−2 performed at 0 VRHE, improved 2-folds from Cd(O,S) without N dopant. Moreover, N5Cd(O,S) exhibited excellent stability of 95.8 % for over 10 h HER testing. This work reveals that N5Cd(O,S) photocathode can capture incident light efficiently within the 3D coral-like microstructure and the contained oxygen vacancies (OVs) in N5Cd(O,S) play a dominant role for photoelectrochemical H2 generation. A specific HER mechanism is proposed based on the experimental results to elucidate the improved photoelectrocatalytic activity.