Enhanced peroxymonosulfate activation by V2O5/g-C3N4 heterojunction for rapid degradation of chloramphenicol: Role of the built-in electric field

In contrast to traditional metal oxides that engage in only two valence state conversions, multivalent metal oxides offer additional electrons, thus accelerating the activation of peroxymonosulfate (PMS) and enhancing catalytic activity. However, the low efficiency of converting between high-valent and low-valent metal ions often limits catalytic performance. In this study, we employed a combined hydrothermal and thermal polymerization strategy to load multivalent vanadium pentoxide (V₂O₅) onto graphitic carbon nitride (g-C₃N₄), thereby constructing a V₂O₅/g-C₃N₄ heterojunction. This heterojunction formed a built-in electric field, facilitating PMS activation and achieving a record-breaking degradation of chloramphenicol (CAP) with a rate constant of 1.13 min⁻¹. Experimental and theoretical analyses indicated that the synergy between radical and non-radical pathways was the primary mechanism for efficient CAP removal. The built-in electric field altered orbital occupancy, reduced the bandgap, and enhanced electron transfer from g-C₃N₄ to V₂O₅, accelerating the conversion between vanadium valence states and enhancing PMS activation. Furthermore, the V₂O₅/g-C₃N₄/PMS system exhibited a broad operational pH range (2–10), robust resistance to matrix interference, and exceptional durability, demonstrating its applicability for mitigating ecological toxicity of CAP and treating typical refractory organic pollutants. This study advances the understanding of how built-in electric fields promote PMS activation and introduces a novel approach for addressing emerging pollutants in aquatic environments.