Dual functionality for hydrogen production and antibacterial activity in Zn-deficient Cu0.1Zn0.9O photocatalyst loaded with Ag nanoparticles of various sizes

This study aims to find an eco-friendly dual material to apply toward energy and antibacterial industry, and to identify their active sites. Cu0.1Zn0.9O nanoparticles (NPs) containing 10 % Cu ions into ZnO framework are synthesized using a facile hydrothermal method, and 10, 20, 30, or 40 nm-sized Ag NPs are loaded to obtain Ag@Cu0.1Zn0.9O particles. From the time-dependent increase in photocurrent density, it is confirmed that the Ag NPs has a photoelectron harvesting ability. Unlike ZnO and Cu0.1Zn0.9O, the Ag@Cu0.1Zn0.9O catalyst well splits water to generate hydrogen. Particularly, the catalyst loaded with 30 nm Ag NPs achieves the highest hydrogen production efficiency of 424.54 μmolg−1. This proves that the active sites generating hydrogen during water splitting are the Ag NP surfaces grafted onto the conduction band of the Cu0.1Zn0.9O particles. Contrastingly, antibacterial performances against Bacillus manliponensis are expressed in all samples of ZnO, Cu0.1Zn0.9O, and Ag@Cu0.1Zn0.9O. The antibacterial performance for the Ag NP-loaded sample slightly increases but it is not significant, indicating that the active site exhibiting the antibacterial activity is the hole+ of the valence band of Cu0.1Zn0.9O. In the end, this study revealed that the advantageous photocatalytic activity does not always express effective antibacterial activity because the active sites exhibiting photocatalytic and antibacterial properties may not be the same. [Display omitted] •An eco-friendly antibacterial material that can replace tin compounds that disturb the marine ecosystem.•Inhibition of exciton recombination on Cu0.1Zn0.9O and photoelectron harvesting on Ag NPs.•Ag NP as the hydrogen generation site and VB-h+ of Cu0.1Zn0.9O as the antibacterial active site.•On Ag@Cu0.1Zn0.9O, the photochemical reaction site and the antibacterial reaction site are not the same.