Novel-CdS-nanorod with stacking fault structures: Preparation and properties of visible-light-driven photocatalytic hydrogen production from water

Abstract

In the present study, CdS nanorod particles with stacking fault structures were hydrothermally synthesized through a dissolution–recrystallization approach in concentrated ammonia solvent, for the first time. Concentrated ammonia solution contained a larger number of hydroxyl ions and a fewer oxygen than that of water, which was beneficial for synthesizing more stable CdS nanorods without oxygen content. Comprehensive characteristics were performed to investigate the influence of stacking fault structures on the photocatalytic activity and stability of CdS nanorod particles. It was revealed that high density of stacking fault structures can be obviously observed within CdS nanorods, which was further proved by transmission electron microscope (TEM), X-ray powder diffraction (XRD) patterns, ultraviolet–visible (UV–vis) absorption spectra, X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF), fluorescence spectra, specific surface areas (BET) and energy-dispersive X-ray spectrometer (EDX). In the dissolution–recrystallization process, many cubic structural units tended to change to hexagonal phase in the CdS crystals, resulting in forming a large number of stacking fault structures. Because of the different band structures of cubic and hexagonal units, a type-II band structure can be formed at the stacking fault area, which significantly promoted the separation rate of photo-generated electrons and holes and then improved the visible-light-driven photocatalytic hydrogen production activity. CdS nanorod particles with stacking fault structures showed much higher photocatalytic activity and stability than that of CdS particles prepared by the conventional hydrothermal method using water as the hydrothermal solvent. This approach by using concentrated ammonia as the hydrothermal solvent opened new avenues in search of oxygen-free photocatalysts.