Visible-light Cu/TiO2@Ag3PO4 heterostructure photocatalyst for selective nitrate reduction and antimicrobial activity

Combination of metal/semiconductor/semiconductor to synthesize heterostructures is a promising method to improve the activity of photocatalysts. Herein, Cu/TiO2@Ag3PO4 heterostructures have been synthesized by coupling sol-gel and precipitation methods with different molar percentages of Cu/TiO2 nanoparticles (NPs) on Ag3PO4 as heterostructures photocatalysts for nitrate (NO3−) reduction. Cu/TiO2 NPs were uniformly decorated on the Ag3PO4 particle surfaces, resulting in an enhanced light absorption. The resulting heterostructures show enhanced photocatalytic activity for nitrate (NO3−) reduction under simulated visible light irradiation. The most active photocatalysts achieved reduction of NO3− up to 97.35% with high nitrogen (N2) selectivity (99.8%) (an initial nitrate concentration of 100 ppm) at 60 min, which is 3.4 and 3.0 times higher than those obtained with the pure Ag3PO4 and Cu/TiO2, respectively. Moreover, the antimicrobial activity against Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) was evaluated by determining the minimum inhibitory concentration (MIC). The optimized ternary heterostructures Cu/TiO2@Ag3PO4 exhibited good antibacterial activities for E. coli and S. aureus (MIC = 0.039 mg mL-1). •Cu/TiO2@Ag3PO4 heterostructures (CTAP) are successfully prepared.•The heterostructures minimizes bandgap to 2.6 eV, upsurge light absorption and charge separation.•Enhanced photocatalytic activity on reduction of nitrate is achieved by Cu/TiO2@Ag3PO4 under visible light.•A mechanism for the photocatalytic reduction of nitrate in the Cu/TiO2@Ag3PO4 heterostructures is proposed.