A radially controlled ZnS interlayer on ultra-long ZnO-Gd(2)S(3)core-shell nanorod arrays for promoting the visible photocatalytic degradation of antibiotics

Abstract

Nanorod (NR) arrays offer commendable visible-light-driven photocatalytic performances. Herein, we describe the construction of a ternary ZnO-ZnS-Gd(2)S(3)nanostructural array in which a sulfidation process is used to decorate a Gd(2)S(3)shell layer with a ZnS interface over vapor-phase-grown vertically-aligned ZnO. With control over the shell-wall thickness, the shell layer of similar to 25 nm wall thickness on the ultra-long ZnO NR arrays exhibited a higher catalytic efficiency close to 3.3, 2.0, 1.2, and 1.8 times those of the bare ZnO, the ZnO-ZnS, the Gd2S3-decorated (similar to 10 nm) and Gd(2)S(3)shell-layered (similar to 40 nm) ZnO-ZnS core-shell structures, respectively. The core-shell geometry and the shell-wall thickness with maximized contact interface afforded increased light absorption in the visible region and effectively retarded the recombination rate of the photoinduced charge carriers by confining electrons and holes separately, thus providing advantages in terms of the degradation of the pharmaceutical residue tetracycline and the industrial pollutant 4-nitrophenol in wastewater.