Pyramid-like CdS nanoparticles grown on porous TiO2 monolith: An advanced photocatalyst for H2 production

Abstract

Efficient production of H2 via solar-light-driven water splitting by a semiconductor-based photocatalyst without noble metals is crucial owing to increasingly severe global energy and environmental issues. However, many challenges, including the low efficiency of H2 evolution, low solar light absorption, excited electron–hole pair recombination, and slow transport of photoexcited carriers, must be resolved to enhance the H2 photoproduction efficiency and photocatalyst stability. Here, a two-step method is used to synthesize advanced H2-generating photocatalysts consisting of pyramid-like CdS nanoparticles grown on a porous TiO2 monolith, which show promising photocatalytic activity for the hydrogen evolution reaction. Furthermore, the stability of the photocatalysts is examined through long-term tests to verify their good durability. Without noble metals as cocatalysts, the photocatalyst can reach a high H2 production rate of 1048.7μmolh−1g−1 under UV–vis irradiation when the ratio of the CdS nanoparticles to TiO2 is 5mol%. This unusual photocatalytic activity arises from the wide-region light adsorption due to the narrow band gap of CdS, effective separation of electrons and holes due to conduction band alignment at the CdS–TiO2 interface, and favorable reaction sites resulting from the porous structure.