Green synthesis of synergistic Ag–Co bimetallic nanoparticles using chickpea sprout water extract for enhanced catalytic reduction of organic pollutants and antibacterial applications

A facile, green synthesis method for Ag–Co bimetallic nanoparticles was developed using chickpea sprout water extract as both the reducing and stabilizing agent. The phytochemical biomolecules in the sprout extract enabled seedless, one-pot synthesis of monometallic (Ag100, Co100) and three compositional bimetallic nanoparticles (Ag25Co75, Ag50Co50, Ag75Co25). Comprehensive characterization by UV–vis, XRD, EDX, NTA, TEM, and SAED confirmed core–shell nanostructures with composition-dependent optical and catalytic properties. The bimetallic Ag25Co75 composition achieved outstanding 4-nitrophenol reduction performance: 83.12% degradation in 180 s with rate constant 0.0128 s−1(0.768 min−1), representing a 1.91-fold enhancement over monometallic silver. Conversely, Ag75Co25 demonstrated superior photocatalytic efficiency, degrading 71.96% of crystal violet dye in 3 h (k = 0.00692 min−1) under solar irradiation. Synergistic bimetallic effects were further demonstrated through enhanced antibacterial activity, with Ag75Co25 exhibiting zone of inhibition values of 16.33–16.50 mm against five bacterial species (Bacillus subtilis, Staphylococcus aureus, Salmonella typhi, Pseudomonas aeruginosa, Escherichia coli). This eco-friendly synthesis approach utilizing agricultural waste represents a sustainable, cost-effective alternative to conventional chemical synthesis, offering multifunctional applications in environmental remediation and antimicrobial treatment.