Ecofriendly Sunlight-Mediated Nontoxic Bimetallic Nanoparticles: Synthesis, Reusable Catalytic Membrane, and Biosensor Applications

Bimetallic nanoparticles (BMNPs) combine the desirable properties of two distinct metals that outperform conventional monometallic nanoparticles (NPs). This work presents a novel ecofriendly silver-copper (Ag–Cu) BMNPs synthesis using sunlight as a green reducing agent, enableing rapid Ag–Cu BMNPs formation at room temperature within 10 min. This method exploiting the facile reduction of Ag⁺ to Ag⁰, which subsequently mediates the reduction of Cu²⁺ to Cu⁰ via water radiolysis-generated species. The Ag–Cu BMNPs were integrated into two reusable catalytic membranes: PTFE@Ag–Cu, formed by immobilizing Ag–Cu BMNPs onto a polytetrafluoroethylene (PTFE) syringe filter, and ACF@Ag–Cu, synthesized via in-situ growth of Ag–Cu BMNPs on activated carbon fiber (ACF) cloth. PTFE@Ag–Cu displays exceptional performance and reusability, converting 2100 mL of 0.15 mM p-nitrophenol to p-aminophenol over 105 cycles at a flow rate of 20 mL min⁻¹. The Ag–Cu BMNPs also exhibit peroxidase-mimic activity, enabling colorimetric H₂O₂ detection with a range of 0–200 mM and a limit of detection (LOD) of 13.3 µM in solution. Further, the Ag–Cu nanoenzyme demonstrates strong potential for electrochemical glucose detection, achieving an LOD of 0.1 µM and sensitivity of 5221 µA × 10⁻⁶ m⁻¹ cm⁻².