Photo-Fenton degradation of tetracycline on nitrogen vacancy and potassium-doped Z-scheme FeOCl/NvCN heterojunction with low H2O2 consumption: Activity and mechanism

The photo-Fenton process effectively enhances the catalytic activity by synergizing the photocatalytic and Fenton reactions, enabling efficient oxidative degradation, and having the advantages of environmentally friendly reagents and relatively simple operation. However, practical application is hindered by the substantial consumption of H2O2. To address this challenge, this study introduces nitrogen vacancies and potassium atoms into g-C3N4, which are then combined with FeOCl to fabricate a Z-scheme heterojunction catalyst. The superior catalytic performance of the catalyst can be attributed to the presence of nitrogen vacancies and potassium atoms. These vacancies and atoms facilitate efficient electron transport, resulting in the removal of 95.74% of tetracycline (TC) within a 60 min timeframe. Additionally, the Z-scheme heterostructure-based catalyst effectively enhanced the separation efficiency of photogenerated carriers. Notably, the FeOCl/NvCN catalyst consumes only 0.67%− 25% of the H2O2 consumed by previously reported catalysts and exhibits a higher primary kinetic rate constant of 0.07252 min−1. The main active species identified in this process are holes (h+) and superoxide radicals (·O2-). Cycling experiments confirm the excellent stability of FeOCl/NvCN, while the Ecosar evaluation demonstrates its effectiveness in reducing the biotoxicity of TC. Overall, this study presents a robust strategy for enhancing catalyst activity and optimizing H2O2 utilization, providing novel insights into TC removal.