Simple and economical photoelectrode modification for efficient ranitidine removal: Improved surface reactivity and...

The effective utilization of both radical and non-radical degradation pathways is crucial. However, achieving the selective occurrence of these two pathways on the same photoelectrode in photoelectrocatalysis (PEC) remains a significant challenge. In this study, we have developed a novel ZnIn₂S₄/electrooxidized graphite felt (ZIS/E-GF) composite photoelectrode prepared through a simple and low-cost electrode substrate modification, which effectively removed ranitidine (RAN) from water. Under PEC reaction conditions at 0.1 V and 0.9 V, ZIS/E-GF demonstrated high RAN removal efficiencies of 92.38 % and 92.26 %, respectively. The experimental results demonstrated that this modification method could simultaneously enhance the photocatalytic and electrocatalytic activities of the material, yielding reaction rates 10.56 and 7.50 times higher than those of the unmodified material, respectively. This excellent degradation performance was attributed to the electrooxidation treatment of GF, which endowed the composite photoelectrode with improved hydrophilicity, light absorption properties, and electron transfer ability. Additionally, density functional theory (DFT) calculations revealed that ZIS/E-GF exhibited lower energy barriers and enhanced surface reactivity for the generation of reactive species (·O₂^- and ¹O₂). More importantly, mechanism analysis showed that ZIS/E-GF exhibited distinct photo/electro synergistic mechanisms under various voltages. This allowed for a seamless transition between radical and non-radical reaction processes through simple voltage adjustments. This capability enables the tailored design of PEC processes to adapt flexibly to complex real-world operating conditions. This work offers a simple yet highly effective new insight into the design of high-performance photoelectrodes that can effectively utilize both radical and non-radical processes.