Fabrication of Cobalt Oxide/MWCNTs/ZnO Nanowires/Zn Plate with Enhanced Photocatalytic Activity in Both Chemical and Microbial Systems

Abstract

A series of cobalt oxide/MWCNTs/ZnO NWs/Zn photocatalyst plates were successfully fabricated by electrochemical deposition of cobalt oxide and functionalized Multi-walled carbon nanotubes (f-MWCNTs) onto previously synthesized ZnO nanowires/Zn plates. The fabricated plates were examined with regard to the oxidative decomposition (acetic acid), antibacterial [Escherichia coli (E. coli) bacteria] and antifungal [Candida albicans (C. albicans)] activity under UV light irradiation and in dark. ZnO NWs/Zn modified plates by cobalt oxide and MWCNTs resulted in enhanced photocatalytic activities in both chemical and microbial systems. CO2 evaluation tests showed that the Cobalt oxide/MWCNTs/ZnO NWs/Zn could completely decompose bacterial cells under irradiation, possibly owing to the enhanced formation of reactive oxygen species (ROSs). Besides, it was found that the surface properties of photocatalyst plates are more vital for the antimicrobial properties due to a larger interface between microorganisms and plates. Therefore, it is expected that ternary Cobalt oxide/MWCNTs/ZnO NWs/Zn photocatalysts should exhibit broad antimicrobial properties. In addition, the Cobalt oxide/MWCNTs/ZnO NWs/Zn exhibited the highest photocatalytic activity in oxidative decomposition of acetic acid, probably due to the lower electron/hole recombination rate. Based on the obtained results, a photocatalytic and an antimicrobial mechanism for the microorganism degradation and acetic acid decomposition over Cobalt oxide/MWCNTs/ZnO NWs/Zn were recommended and discussed.