One-pot synthesis of Ag/AgCl@SiO2 core–shell plasmonic photocatalyst in natural geothermal water for efficient photocatalysis under visible light

• Ag/AgCl@SiO2 photocatalyst was synthesized in geothermal water by a one-pot method.
• Geothermal water, a clean and cheap resource, acted as chlorine and silica source.
• SiO2 shell coated on the surface can inhibit aggregation and stabilize Ag/AgCl.
• Ag/AgCl@SiO2 exhibited high visible-light photocatalytic activity and stability.

Ag/AgCl@SiO2 core–shell plasmonic photocatalyst was directly synthesized by a one-pot green method at room temperature using silver nitrate (AgNO3) as silver source and geothermal water as chlorine and silica source, wherein no surfactants, polymers, reducing agents or other additives were required. It is demonstrated that SiO2 coated Ag/AgCl products can be formed uniformly by simply adding an aqueous solution of AgNO3 into the natural geothermal water. The as-synthesized Ag/AgCl@SiO2 samples exhibit excellent photocatalytic performance and stability for the degradation of organic pollutants under visible light irradiation, owing to the strong localized surface plasmon resonance (LSPR) of the photoexcited metallic Ag species. The trapping experiments confirmed that holes (h+) were the main active species in the photocatalytic process. The silica shell on the surface of Ag/AgCl can protect Ag nanoparticles from deterioration and increase the stability of Ag/AgCl plasmonic photocatalyst. Direct synthesis of Ag/AgCl@SiO2 photocatalysts in this work might open up new insights into the application of cheap geothermal water resources and provide new opportunities for facile fabrication of visible-light-driven Ag/AgCl-based plasmonic photocatalyst.

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