Fabrication and photocatalytic performance of a Zn_xCd_(1-x)S solid solution prepared by sulfuration of a single layered double hydroxide precursor

摘要

Zn_xCd_(1-x)S nanoparticles have been successfully synthesized by reaction of a single precursor - a Zn,Cd,Al-containing layered double hydroxide (ZnCdAl-LDH) - with H2S. The ZnxCdi_xS nanoparticles are homogeneously distributed within the confinement of an amorphous alumina matrix, in marked contrast to the aggregation that occurs with Zn_xCd_(1-x)S prepared by conventional coprecipitation. The photoactivities of the Zn_xCd_(1-x)S nanoparticles for methylene blue (MB) photodegradation increased with decreasing Zn mole fraction x, and the best performance was achieved with a Zn mole fraction of 0.20. The Zn_xCd_(1-x)S materials exhibited significantly better photocatalytic performance than Zn_xCd_(1-x)S with the same composition obtained either by a coprecipitation method or by sulfuration of a physical mixture of Zn Al-LDH and Cd,Al-LDH precursors. This suggests that the ordered arrangement on an atomic level of the metal cations within the LDH layers leads to a homogeneous array structure of the Zn_xCd_(1-x)S solid solution, which suppresses the recombination of photoexcited electrons and holes, leading to improved photocatalytic activity. Our method provides a way to fabricate new types of chalcogenide semiconductor photocatalysts which are active under illumination by visible light.