Facile preparation of Z-scheme CdS-Ag-TiO2 composite for the improved photocatalytic hydrogen generation activity

Photocatalytic hydrogen evolution is a prospective approach to solve the problem about energy crisis by fossil fuel combustion. As the good candidate to generate hydrogen under visible light irradiation, the rapid charge recombination and easy photocorrosion of pure CdS nanomaterials limited its hydrogen generation activity and photocatalytic stability. Here we constructed a novel ternary Z-scheme CdS-Ag-TiO2 composite based on CdS nanowires by a three-step process to solve this problem. Compared with CdS-TiO2 and CdS, the Z-scheme CdS-Ag-TiO2 composites could obviously extend the light-absorption region, accelerate the transfer rate of charge-separation, and possess stronger redox capability. The prepared Z-scheme CdS-Ag-TiO2 composites show high photocatalytic hydrogen evolution rate of 1.91 mmol h(-1) g(-1), which is 1.50 and 2.45 times that of CdS-TiO2 heterojunction and pure CdS nanowires. The Z-scheme photocatalytic system exhibits the synergetic effects due to more efficient charge transfer and surface plasmon resonance absorption. Ag nanoparticles used as electron mediator could decrease the recombination of the photocarriers, alter the path of charge transfer and suppress the photocorrosion. This work opens up a new way for the novel Z-scheme photocatalytic systems that suppress the photocorrosion of CdS, and has a promising application in the photocatalytic water splitting. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.