Simultaneous Realization of Direct Photoinduced Deposition and Improved H₂-Evolution Performance of Sn-Nanoparticle-Modified TiO₂ Photocatalyst

Abstract

The exploitation and preparation of novel non-noble-metal cocatalysts are particularly crucial to develop high-activity photocatalytic hydrogen-generation materials. In this study, metallic Sn nanoparticle, a new hydrogen-generation cocatalyst, was effectively integrated with the conventional TiO2 photocatalyst to greatly boost the hydrogen-production reaction via a direct photoinduced method. Herein, the direct photoinduced synthesis of Sn nanoparticle-deposited TiO2 photocatalysts and their enhanced H2-generation activity can be easily and simultaneously realized in an ethylene glycol–ethanol system. The Sn nanoparticles were very small (ca. 2 nm) and uniformly deposited onto the TiO2 surface to synthesize highly efficient Sn/TiO2 photocatalysts via the formation of Sn(II)-EG complex molecules and their following in situ photoreduction method. Photocatalytic results indicated that metallic Sn cocatalyst could dramatically promote the H2-generation activity of TiO2 photocatalyst, and the resultant Sn/TiO2(3 wt %) presented the highest H2-production rate with a value of 553.1 μmol h–1 g–1, which is 43.9 times as that of pure TiO2 (12.6 μmol h–1 g–1). Thus, an electron-cocatalyst-mediated mechanism is raised to explain the promoted H2-generation efficiency of TiO2 photocatalyst, namely, the metallic Sn cocatalyst can act as the electron receiver to quickly capture photoexcited electrons and serve as the interfacial hydrogen-generation site to enhance the hydrogen-generation rate. Considering the facile synthetic route, earth abundance, and high activity, the metallic Sn cocatalyst would have enormous prospect for the development of efficient photocatalysts applied in different fields.