Homogeneous Electron-Extraction and Effective Interfacial Electron Transfer of Electronic Donor Photosensitizer Molecules Expedites Photocatalytic H2 Evolution of CdS Nanocatalysts

In the practical photocatalytic hydrogen evolution process, the light absorption, charge carrier separation, and optimizing the reaction kinetics are the pivotal factors that restrict photocatalytic performance. Here, a planar triphenylamine-based photosensitizer CMoTV is synthesized to synergistically enhance all three photocatalytic steps in cadmium sulfide (CdS) hydrogen evolution by homogeneous electron-extraction and rapid interfacial electron transfer. Abundant CMoTV radical anions could be achieved by rapid reductive quenching of photoexcited CMoTV by lactic acid in solution. Formation of in situ complex through effective electron transfer from photosensitizer radical anions to CdS surface improves surface reaction kinetics. By employing CMoTV as a molecular electron-donating photosensitizer, the system achieves a remarkable hydrogen evolution rate of 19.2 mmol g^-1 h^-1, along with exceptional stability under 40 h of irradiation and five consecutive cycles. This work not only provides a robust method to amplify the photocatalytic activity of CdS but also offers new design principles for high-performance semiconductor-based photocatalytic systems.