Low-H2O2-consumption Mg-doped BC/ZnO/g-C3N4 catalysts for efficient pollutant degradation via enhanced electron transfer

Abstract

Energy consumption is a critical factor that impacts the effectiveness of Fenton-like reactions in the removal of refractory organic pollutants from water. In this study, we utilized raw materials directly for synthesizing the catalyst. We developed a novel photo-Fenton catalyst, Mg-BC/ZnO/g-C₃N₄, through a one-step pyrolysis process that employed a precursor mixture. This catalyst demonstrates exceptional Fenton-like catalytic activity for degrading various pollutants while minimizing H₂O₂ consumption. Experimental results demonstrated that the optimized catalyst effectively activates H₂O₂ to degrade organic pollutants, achieving a 50% higher degradation rate than the non-doped magnesium catalysts. It is noteworthy that the injection of photogenerated electrons positively influences peroxide activation. Specifically, the degradation efficiency of methylene blue increased from 88.3% to 97% upon the introduction of LED light into the reaction system. Here, Mg functions as an electron mediator, facilitating charge transfer pathways and accelerating the directional transport of electrons to active sites. This efficient and organized electron transfer enhanced the availability of reducing electrons, which are crucial for the activation of H₂O₂. This mechanism significantly reduces the consumption of H₂O₂, thereby decreasing overall energy expenditure. Additionally, quenching experiments and electron spin resonance (ESR) spectroscopy further confirm that hydroxyl radicals and holes are the primary active species involved in the reaction.