Using waste silver metal in synthesis of Z-scheme Ag@WO3-CeO2 heterojunction to increase photodegradation and electrochemical performances

다국어 초록 (Multilingual Abstract)

Design of a Z-scheme heterojunction structure is eco-friendly due to its multi-nanocatalyst performanceslike wastewater treatment, antibacterial and electrochemical activity. Herein, Ag was extracted fromwaste batteries in a nitric acid leaching manner. Also, WO3 nanorods and WO3-CeO2 were synthesizedby the surfactant-assisted hydrothermal acidic and sol–gel methods, respectively. Silver nanoparticleswere doped by wet impregnation method to prepare ternary (Ag@WO3-CeO2) and binary (Ag@WO3and Ag@CeO2) heterojunctions. The band gap of the prepared Ag@WO3-CeO2 was remarkably diminishedin comparison with the rest of the sample (from 2.73 to 2.59 eV). The Langmuir-Hinslewood modelshowed that ternary systems can degrade methylene blue twice as much as WO3-CeO2 and seven timesmore than single-component systems. This was due to the presence of silver as a mediator for the transferof photogenerated electrons between two semiconductors. Also, methylene blue was degraded by morethan 90.8% efficiency. Electrochemical impedance spectroscopy (EIS) analysis confirmed that the chargetransfer resistance of Ag@WO3-CeO2 was decreased by more than 50%. The results of bactericidal activenessconfirmed elevated inhibition capability of Ag@WO3-CeO2 towards E.coli with 99% degradation. Xrayfluorescence (XRF) results confirmed that 98% of silver can be re-extracted after 5 photocatalytic useswhich is a material with green technology.