Exploring ZnO microcrystals through experimental design: from solar photocatalysis to antibacterial activity

The concern on emerging pollutants and antibiotic resistance is pushing scientists to advance materials-based approaches by expanding their wet chemical synthetic parameter space. Herein, we leverage Design of Experiments (DoE) approach to optimize the synthetic yield and photocatalysis performances of wet chemistry prepared ZnO microcrystals. By varying three independent parameters (precursor salt concentration, reaction time and KCl concentration), we correlated synthetic yield and photocatalytic activity via Response Surface Methodology and Principal Component Analysis. ZnO microcrystals were incorporated into cellulose-based supports, facilitating their sustained release in solution. Photocatalytic efficiency was assessed on methylene blue degradation under simulated solar irradiation, and the role of photogenerated reactive radical species was elucidated. The antibacterial properties of the ZnO were investigated, underscoring the importance of their colloidal stability and finding that the amount of the released zinc ions was a critical factor in triggering their antibacterial activity, highlighting the multifunctional potential of these microstructures.