Boosted visible-light-driven degradation over stable ternary heterojunction as a plasmonic photocatalyst: Mechanism exploration, pathway and toxicity evaluation

Abstract

The incorporation of plasmonic metals into semiconductors forming heterojunction photocatalysts is a promising route to enhance the photocatalytic performance in visible light. In this work, we reported the visible-light-driven one-dimensional (1D) nanostick silver/silver sulfide (Ag/Ag2S) photocatalyst combining with two-dimensional (2D) nanosheet reduced graphene oxide intersected by hollow structure (h-RGO) was prepared via a feasible approach at room temperature. The density of Ag depositing on the surface of Ag2S was easily tuned by the concentration of sodium borohydride and the silicon dioxide nanospheres were employed as templates in the preparation of h-RGO by the layer-by-layer (LBL) assembly. The ternary plasmonic Ag/Ag2S/h-RGO photocatalysts exhibited better photocatalytic performance for degradation of naphthalene (95.95%) and 1-naphthol (98.65%) under visible light than the pure Ag2S, composite Ag/Ag2S and composite Ag/Ag2S/RGO. Localized surface plasmon resonance of Ag, heterojunction formed between Ag/Ag2S and RGO and the unique characteristics of h-RGO, which included higher specific surface areas, more efficient reflections of light and more active sites than RGO for boosting separation efficiency of charge carriers, were all responsible for such enhancement. By combining the characterization results with various computations, the mechanism, potential degradation pathways and the toxicity of the generated intermediates for photodegradation were examined. In addition to offering profound insight into the expansion of effective plasmonic photocatalysts with novel structures, the current study is beneficial to ease the environmental crisis to a certain extent.