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 Al-ZnxCd1−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 Al-ZnxCd1−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.

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► Uniform distributed mesoporous ZnxCd1−xS nanoparticles were fabricated.
► Using selective leaching of amorphous alumina from as-prepared Al-ZnxCd1−xS.
► The abundance of hydroxyl groups formed on the surface of mesoporous ZnxCd1−xS.
► Their photocatalytic activity increased with the decline of alumina content.
► The homogeneous mesoporous structure leading to the higher photocatalytic activity.