Enhanced photocatalytic hydrogen evolution along with byproducts suppressing over Z-scheme CdxZn1-xS/Au/g-C3N4 photocatalysts under visible light

Inspired by natural photosynthesis, a new series of Z-scheme CdxZn1-xS/Au/g-C3N4 photocatalysts were synthesized via depositing Au particles on g-C3N4, followed by anchoring CdxZn1-xS solid solution on the pre-formed Au/g-C3N4 for photocatalytic hydrogen evolution. Their structure, morphology and optical property were investigated in detail. Photocatalytic activities of the developed photocatalysts for water splitting were evaluated under visible-light irradiation (lambda > 420 nm) using glucose as electron donor. The highest hydrogen evolution rate of 123 mu mol g(-1) h(-1) is achieved by Cd0.8Zn0.2S/Au/g-C3N4,which is 52.2 and 8.63 times higher than that of Au/g-C3N4 and CdS/Au/g-C3N4, respectively. The results of photoluminescence spectra, photoelectrochemical and time-resolved photoluminescence spectra indicate that the improved photocatalytic activities for CdxZn1-xS/Au/g-C3N4 are due to the efficient separation of photogenerated carriers. In addition, it is noteworthy that the undesired byproducts CO and CO2 are greatly reduced by introducing CdxZn1-xS over /Au/g-C3N4 surface. In the photocatalytic process, gluconic acid originated from the reaction of photogenerated hydroxyl radical with glucose plays a vital role on suppressing the formation of the gas byproducts. The present work will provide a new strategy to design Z-scheme photocatalysts with enhanced efficiency for water splitting along with suppressing the byproducts. (C) 2017 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.