Abstract
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−2vs. 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.
Highlights
Heterogeneous photocatalysis of pollutants over semiconductor materials has recently emerged as an efficient method for purifying water and air
Transmission electron microscopy (TEM) images presented in Fig. 2 indicate Ag and Ag2S NPs were separately dispersed on the surface of TiO2
It can be concluded that Ag2S NPs adhere on the surface of TiO2 nanorods
Summary
Heterogeneous photocatalysis of pollutants over semiconductor materials has recently emerged as an efficient method for purifying water and air. Different methods such as metal decoration,[3,4] metallic ion doping,[5] non-metal doping,[6,7] and dye sensitization[8,9] have been proposed to modify and narrow its band gap, and enhance its photocatalytic activity under visible light radiation.[10,11,12]. Decorating TiO2 with metal, as one of the promising methods to develop highly efficient visible light photocatalysts, aState Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China bKey Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China. Some noble metals such as Ag and Au, exhibit strong UV-vis absorption due to their plasmon resonance, produced by the collective oscillations of surface electrons.[15]
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