Mesoporous Monoclinic CaIn2S4 with Surface Nanostructure: An Efficient Photocatalyst for Hydrogen Production under Visible Light

A novel ternary sulfide photocatalyst of monoclinic CaIn2S4 with excellent photocatalytic H2 evolution activity is synthesized via a high-temperature sulfurization approach. The precursor orthorhombic CaIn2O4 can be converted in situ to monoclinic CaIn2S4 by using H2S gas as the sulfurization reagent once the sulfurization temperature exceeds 773 K. The obtained yellow powders have a mesoporous structure and a chain-shape morphology with large surface area and high pore volume. SEM and TEM observations indicate that specific nanostep structures are formed on the surface of monoclinic CaIn2S4. Under visible light irradiation, monoclinic CaIn2S4 exhibits considerable performance for photocatalytic hydrogen production. A high H2 evolution rate of 30.2 μmol/h with good stability is achieved from Na2S/Na2SO3 aqueous solution with the deposition of 0.5 wt % Pt nanoparticles, 30 times higher than that of cubic CaIn2S4, which makes it a new promising candidate photocatalyst for hydrogen production. This work can provide an effective approach to the fabrication of other mesoporous sulfide photocatalysts with high performance.