CoS@TiO2 S-scheme heterojunction photocatalyst for hydrogen production from photoinduced water splitting

To synthesize durable catalysts, cobalt sulfide (CoS) microsheet particles are woven into a polyhedral cage shape to prevent dissolution and light corrosion during photochemical reactions. Titanium dioxide (TiO2) nanoparticles with excellent stability against water and light are used to enclose the cage. The surface of the dodecahedral CoS particle is positively charged, and the surface of the spherical TiO2 particles is negatively charged, resulting in a core–shell shaped [email protected]2 heterojunction particle. The [email protected]2 heterojunction catalyst has a stronger ability to absorb visible light and greater photocatalytic hydrogen evolution activity than pure TiO2 or CoS catalysts: When lactic acid is used as an electronic sacrificial agent, the hydrogen production of [email protected]2 reaches 1945 μmol g−1 for 10 h, and the catalytic activities are 114.4 and 13.2 times those of CoS and TiO2, respectively. Spin-trapping ESR results reveal that charge transfer in the core–shell shaped [email protected]2 heterojunction follows the S-scheme mechanism. The excellent catalytic activity of the core–shell shaped [email protected]2 heterojunction catalyst is because of its favorable bandgap location for water splitting, higher photocurrent density, lower photoluminescence, and having strong redox sites. These factors ultimately delay the recombination of photo-induced electron/hole pairs and, as a result, high catalytic efficiency is stably maintained up to the fifth recycling test.