Palladium-Copper Alloy Nanoparticles Supported on Carbon Nitride Nanosheets as a Photocatalyst for Degradation of Ciprofloxacin

Optimization regarding the electronic structure of nanometal cocatalysts via alloying is considered as a promising strategy to regulate the formation of reactive oxygen species (ROS) in photocatalytic degradation. Herein, a series of g-C₃N₄-supported PdCu alloy cocatalysts were constructed to investigate the regulatory effect and mechanism of alloying on photocatalytic active species. Photocatalytic degradation experiments using ciprofloxacin (CIP) as a model pollutant demonstrated that optimal alloying with PdCu (Cu ≤ 0.5 wt %) significantly boosts the production of active species and incrementally enhances the contribution of superoxide anions (·O₂^-). The introduction of Cu leads to the redistribution of surface electrons in the PdCu alloy, resulting in a gradual strengthening of the O₂ adsorption as the Cu content increases up to 0.5 wt %. The CIP degradation rate reaches a maximum of 80.5% at pH 6.7. Inorganic ions such as Na⁺ and Ca²⁺ inhibit degradation, while low concentrations of Fe³⁺ promote that. The CIP degradation rate in actual water samples ranges from 71.1 to 78.2%. Furthermore, the degradation pathway initiated from carbonyl destruction induced by a higher ·O₂^- concentration was proposed. This comprehensive study provides valuable insights into the design of alloyed photocatalysts, emphasizing the significance of optimizing metal composition to regulate ROS generation and enhance photocatalytic efficiency.