Photocatalytic hydrogen evolution from water over chromosilicate-based catalysts

Abstract

Hydrogen evolution using photocatalytic water splitting over semiconductors is an area of great interest due to the generation of a sustainable clean energy fuel for the future. Herein, photocatalytic production of H₂ with a high-efficiency was accomplished using chromosilicate as a support decorated with CdS or CdS sensitized TiO₂ composites (CdS/C or CdS–TiO₂/C) under optimum conditions. The rate of hydrogen generation over virginal CdS can be increased by up to ∼5 times when immobilized with 10% wt within the structure of chromosilicate as a support under visible light. The rate was further increased to ∼10 times when the CdS in the mentioned composite coupled with TiO₂ to obtain a CdS–TiO₂/C composite. This proficient photocatalytic hydrogen generation can be attributed, firstly, to the presence of CdS nanocrystals that modify the energy levels of the conduction and valence bands for the purpose of extension to the visible region in the coupled semiconductor composite; secondly, to the contribution of chromosilicate that serves as an electron collector and carrier to efficiently lengthen the lifetime of photogenerated electron–hole pairs from CdS–TiO₂ composites. This study developed highly efficient molecular sieve-based photocatalysts that utilize visible light as an energy source.