Full-spectrum responsive dual-defect mediated S-scheme heterojunction for cooperative benzyl alcohol conversion and H2 evolution

The construction of a dual system for photocatalytic redox reaction is an effective strategy to promote photocatalytic decomposition of water for H2 evolution, which not only overcomes the slow process of water oxidation during water decomposition but also combines with biomass conversion to produce high-value chemicals. Herein, three-dimensional full-spectrum responsive P–MoS2–ZnIn2S4–2 (P–M−Z−2) flower-like materials are prepared for efficient production of H2 coupled with benzyl alcohol oxidation by constructing S-scheme heterojunction and P-doping to modulate the sulfur vacancies. In this case, the hole trap P doping site and the electron trap sulfur vacancy have a synergistic effect of regulating the charge flow to realize the photogenerated carrier separation more effectively. The resulting P–M−Z−2 shows a remarkable photocatalytic effect (3763.2 μmol·h−1·g−1 for H2 evolution and almost 100 % yield of benzaldehyde) under visible light irradiation, which was about 9 times higher than that of pure ZnIn2S4. More importantly, the optimized P-M−Z−2 displays H2 evolution efficiency of 31423.6 μmol·h−1·g−1 and 31297.7 μmol·h−1·g−1 for benzaldehyde generation under simulated sunlight irradiation (AM 1.5G). The construction of S-scheme heterojunctions retains a higher redox potential for the catalysts, which improves the redox capacity and thus the photocatalytic performance, as well as the heterojunctions facilitate the separation and transport of photogenerated carriers. This work not only reveals the strategy to enhance the photocatalytic performance by doping modulation of sulfur vacancies and construction of S-scheme heterojunctions but also provides ideas for realizing efficient valorization of biomass platform compounds.