One-Pot Growth of Dual-Semiconductor Coshells on Au Nanorods with Tunable Band Arrangements for Efficient Photocatalysis

Abstract

Metal core@semiconductor shell hybrids are regarded as promising candidates for plasmon-enhanced photocatalysis, but it remains a challenge to build semiconductor junctions on the shell region for further improved photocatalysis. Herein, Au core@dualsemiconductor coshell hybrids, whose shell was made by two different metal sulfides, were prepared by a one-pot direct growth method based on Au nanorods for highly improved photocatalysis for the first time. By inducing two different metal ions at the step of shell growth in a surfactant-assisted hydrothermal reaction, three types of Au@ dual-semiconductor hybrids were prepared. In these hybrids, Au and two semiconductors intimately contact with each other, and three types of semiconductor heterojunctions including type I (ZnS−CdS), type II (Cu 2−x S−Bi 2 S 3 ), and Z-scheme (Bi 2 S 3 −CdS) are grown on Au nanorods. The as-prepared Au@dual-semiconductor hybrids show excellent photocatalytic activity on degrading rhodamine B under light irradiation, which is much higher than that of Au@single-semiconductor, semiconductor junctions, and Au@semiconductor@semiconductor hybrids with a double-layer shell. The enhanced mechanism can be ascribed to the accelerated carrier transfer and separation driven by the internal electric fields (IEFs) between semiconductors. Meanwhile, the plasmoninduced hot electron injection from Au to semiconductors can be promoted due to the cooperation of the Schottky junction or ohmic contact at metal−semiconductor interfaces and IEFs at semiconductor−semiconductor interfaces, which further promote the photocatalysis.

Kinetic Comparison of Photocatalysis with the Photo-Fenton Process on the Removal of Tetracycline Using Bismuth-Modified Lanthanum Orthoferrite Nanostructures

“…Various studies can be found in the literature on the kinetics of photocatalytic and photo-Fenton degradation of pollutants. − Generally, photo-Fenton degradation follows pseudo-first-order kinetics, wherein the production of major reaction radicals gets accelerated due to the redox reaction of Fe or Fe-like species. Instead, the kinetics of photocatalysis can encompass a range of behaviors, including pseudo zero-order, pseudo-first-order, or pseudo-second-order reactions .…”