Highly efficient visible-light-driven photocatalytic hydrogen production from water using Cd0.5Zn0.5S/TNTs (titanate nanotubes) nanocomposites without noble metals

Abstract

Semiconductor based nanocomposites are quite promising in the areas of photocatalysis and photovoltaics due to their efficient charge separation. Herein, we demonstrated a simple and green one-step method to prepare novel Cd_0.5Zn_0.5S/TNTs (titanate nanotubes) nanocomposites with low-priced metallic elements. Transmission electron microscopy (TEM) images revealed that an enwrapped architecture was achieved for Cd_0.5Zn_0.5S/TNTs nanocomposites. Cd_0.5Zn_0.5S nanoparticles of ca. 90 nm were tightly surrounded by the network of titanate nanotubes, which led to the high dispersity of Cd_0.5Zn_0.5S nanoparticles and the intimate multipoint contacts between Cd_0.5Zn_0.5S and TNTs. Highly efficient charge separation was finally achieved in the hybrid Cd_0.5Zn_0.5S/TNTs through the enwrapped structure. Under visible light irradiation Cd_0.5Zn_0.5S/TNTs displayed improved activities compared to the single Cd_0.5Zn_0.5S for hydrogen evolution. The effect of sacrificial reagents on the photocatalytic activity of Cd_0.5Zn_0.5S/TNTs was discussed. The highest apparent quantum yield of 38.1% at 420 nm was achieved. This value is among the highest efficiencies for the noble-metal free photocatalysts ever reported. Meanwhile, Cd_0.5Zn_0.5S/TNTs showed good stability for hydrogen production, and the content of toxic cadmium was as low as 4.0 wt% of the nanocomposites. These factors are of great significance for their application in the field of solar energy conversion.