Clay Mineral-Derived Silica Nanosheets as a Sustainable Platform for Photochemical Synthesis of Supported Metal Catalysts

Clay minerals and their derivatives are valued for their unique, low-dimensional nanostructures. It is imperative to explore the characteristics of nanoclay-based matrix materials for the green synthesis of functional composites. This study reveals the defect-induced semiconductor-like optical properties of kaolinite clay-derived silica nanosheets (SiNSs) and employs SiNSs as a sustainable support and photoinduced reducing agent for the photochemical synthesis of supported metal nanoparticles (NPs). Results show that SiNSs feature defects that show UV absorption ability, a band gap of 2.99 eV, and higher photogenerated carrier separation efficiency than kaolinite and fumed nanosilica. Consequently, the photoexcited electrons of SiNSs under UV irradiation efficiently reduce Ag/Cu-amine precursors to produce SiNS-supported Ag-only and AgCu-alloy NPs. Furthermore, the impact of UV intensity on the Ag/Cu ratio and composition of alloy NPs due to the metal–support interaction and alloying effect is clarified. The optimal AgCu/SiNS-5 composite consisting of Ag 0.35 Cu 0.65 alloy NPs (∼12 nm) exhibits superior catalytic activity for p -nitrophenol reduction within 40 s with a turnover frequency of 4.36 min –1 owing to high adsorption and reactivity of the interfacial and alloying active sites, and multiple electron transport pathways enabled by the alloying effect of Ag 0 /Cu + /Cu 0 /(AgCu) 0 . This work indicates the great potential of clay-derived SiNS’s optical properties in photochemical synthesis of supported metal catalysts, emphasizing the key roles of metal–support interaction and alloying effect in synthesis and catalysis.