Tuning ZnO photocatalysts via C and Ce Co-doping: a comparative approach using hydrothermal and microwave synthesis†

In this study, C- and Ce-doped ZnO materials were synthesized by two methods: hydrothermal method (CCZ-HT) and microwave method (CCZ-MA), both using the same starting materials. The different heating stages of the methods produce distinct morphologies, doping concentrations, and some other characteristics. CCZ-HT consists of nanoellipsoids, while CCZ-MA consists of nanoflakes. The doping concentrations of cerium and carbon in CCZ-MA are higher than those in CCZ-HT. The types of crystal defects in the doped materials are different, leading to differences in their absorption and emission properties. The band gap energy of CCZ-MA is 2.85 eV, which is lower than that of CCZ-HT (2.92 eV). While CCZ-HT does not exhibit near-infrared emissions, CCZ-MA exhibits relatively strong emissions. CCZ-HT and CCZ-MA had a degradation capacity for ofloxacin (Ofx) under visible light that was 2.63 and 3.38 times superior to that of pure ZnO, respectively. The addition of Ce and C improved the band structure by slightly moving the conduction band and reducing the band gap, which allowed for better light absorption in the visible range and helped separate charge carriers. These enhancements immediately facilitated enhanced photocatalytic efficacy in the breakdown of ofloxacin. The CCZ-MA material exhibited superior photocatalytic activity due to its advantageous shape, increased surface area, and enhanced charge trapping capability associated with flaws. The functions of photo oxidized fragments and reaction intermediates were also examined. This study postulated a photodegradation mechanism for Ofx.