Construction Of Highly Efficient Visible-light-driven Plasmonic AgCl:Ag Heterojunction Nanophotocatalysts

Recently, many researches focused on the photocatalysis-oxidation, which is a senior oxidation technology with high efficiency, stability towards decompostions of organic pollutants. Traditional photocatalyst like TiO₂ with large band gaps confines it response in the ultraviolet (UV) region, leading to low utilization efficiency of solar spectrum. As a result, many methods have been explored to narrow their large bandgaps in order to improve the absorption coefficient in the visible region. A class of novel heterojunction plasmonic nanophotocatalysts, such as AgX decorated with noble metals, combining the surface plasmon resonance (SPR) property of noble metal nanoparticles,s, metal-semiconductor contact and photocatalytic property, exhibits outstanding photocatalytic performance.In this thesis, we have achieved a series of heterojuction plasmonic nanophotocatalyst of AgCl:Ag using wet chemical reduction, and visible-light irradiation of AgCl nanocubes. For example, the first AgCl:Ag^-1 nanphotocatalyst was prepared by microemulsion and followed by NaBH₄ reduction; the second AgCl:Ag-2 was fabricated by microemulsion and light-induced reduction method. The results of X-ray diffraction (XRD), Scanning Electronic Microscopy (SEM), EDS, and UV-vis spectra showed that the two photocatalysts have uniform sizes and exhibit strong absorption in the visible region. Furthermore, the nanophotocatalyst obtained by visible light illumination exhibits superior photocatalytic activity and durability towards the decomposition of organic pollutants, such as methyl orange.At the same time, we also prepared nanophotocatalyst AgCl:Ag by polyol precipitation process and light-induced chemical reduction. Under the visible light irradiation, the decomposition rate of the MO-dye over AgCl:Ag is estimated to be about 2.5×10^-3 mgs^-1. Moreover, the catalyst can be reused for 50 times without loss of activity, indicating its potential applications in the environmental purificatiaon and related fields.Finally, the wide applicability of the as-synthesized AgCl:Ag plasmonic photocatalyst was evaluated by testing the decomposition of typical dye molecules like methylene blue, crystal violet, methyl red, rhodamine B, and malachite green. The results indicated that these dye molecules can be effectively decomposed under visible illumination with the assistance of AgCl:Ag nanoparticles. The high activity, strong durability, and wide applicability of the obtained plasmonic nanophotocatalysts enable them to be promising materials for practical applications in environmental remediation and waste water disinfection.