Efficient photocatalysis with graphene oxide/Ag/Ag2S-TiO2 nanocomposites under visible light irradiation

摘要

Lack of visible light response and low quantum yield hinder the practical application of TiO2 as a high-performance photocatalyst. Herein, we present a rational design of TiO2 nanorod arrays (NRAs) decorated with Ag/Ag2S nanoparticles (NPs) synthesized through successive ion layer adsorption and reaction (SILAR) and covered by graphene oxide (GO) at room temperature. Ag/Ag2S NPs with uniform sizes are well-dispersed on the TiO2 nanorods (NRs) as evidenced by electron microscopic analyses. The photocatalyst GO/Ag/Ag2S decorated TiO2 NRAs shows much higher visible light absorption response, which leads to remarkably enhanced photocatalytic activities on both dye degradation and photoelectrochemical (PEC) performance. Its photocatalytic reaction efficiency is 600% higher than that of pure TiO2 sample under visible light. This remarkable enhancement can be attributed to a synergy of electron-sink function and surface plasmon resonance (SPR) of Ag NPs, band matching of Ag2S NPs, and rapid charge carrier transport by GO, which significantly improves charge separation of the photoexcited TiO2. The photocurrent density of GO/Ag/Ag2S-TiO2 NRAs reached to maximum (i.e. 6.77 mA cm(-2) vs. 0 V). Our study proves that the rational design of composite nanostructures enhances the photocatalytic activity under visible light, and efficiently utilizes the complete solar spectrum for pollutant degradation.