Novel mesoporous ZnxCd1-xS nanoparticles as highly efficient photocatalysts

Porous semiconductor photocatalysts which are active under illumination by visible light have attracted extensive attention recently due to their remarkable well-designed physical and chemical properties. Here, novel mesoporous ZnxCd1-xS nanoparticles have been successfully fabricated by a two-steps strategy: Al-ZnxCd1-xS nanoparticles which are homogeneously distributed within the confinement of an amorphous alumina matrix was first synthesized by in situ gas-solid reaction of a single precursor a Zn2+,Cd2+,Al3+-containing layered double hydroxides (ZnCdAl-LDHs)-with gaseous H2S; subsequently, selective leaching of amorphous alumina by sodium hydroxide solution from the as-prepared AlZnxCd1-xS nanoparticles was carried out, with the aim of achieving the introduction of mesopority in the chalcogenide semiconductor. The resulting mesoporous ZnxCd1-xS nanoparticles can retain the uniform distributed structure with a network-like manner after the selective leaching of amorphous alumina. The absorption edge of the mesoporous ZnxCd1-xS exhibit a monotonic blue shift within the visible light region as the amount of residual alumina decreased. The photocatalytic activities of the mesoporous ZnxCd1-xS samples for the photodegradation of methylene blue (MB) dye molecules increase with the decline of alumina. And, the mesoporous ZnxCd1-xS exhibits an enhanced photocatalytic performance compared to the pure CdS sample obtained from the same procedure without Zn2+, the unleached AlZnxCd1-xS sample and the sample obtained by a coprecipitation method with the same composition. The homogeneous structure of the mesoporous ZnxCd1-xS and the abundant surface hydroxyl groups are proposed to be beneficial to the generation of hydroxyl radicals, identified by electron spin resonance (ESR) spectra, leading to the higher photocatalytic activity. (C) 2012 Elsevier B.V. All rights reserved.