Synthesis of N-C₃N₄/Cu/Cu₂O: New strategy to tackle the problem of Cu₂O photocorrosion with the help of band engineering

The photocorrosion behavior of semiconductors was a widely concerned problem, which has posed a great challenge to the durability of photocatalysts. In this paper, a photocatalyst with the Z-scheme structure (N-C3N4/Cu/Cu2O) was prepared in order to alleviate Cu2O photocorrosion. Its physicochemical properties were systematically characterized and the photocatalytic activity was evaluated by degrading tetracycline. The results indicated that, compared with C3N4, Cu2O and even the composite of them, the N-C3N4/Cu/Cu2O exhibited the best photocatalytic performance. Nitrogen doping significantly increased the photocatalytic activity of C3N4, and thus improved the photocatalytic performance of the composite N-C3N4/Cu/Cu2O. Additionally, metallic Cu was introduced at the interface between N-C3N4 and Cu2O to construct Schottky junctions, with the help of which a Z- scheme structure was constructed. Consequently, the recombination of photoexcited carriers was effectively inhabited, thus alleviating Cu2O photocorrosion. Even if a part of Cu2O was photocorroded, N-C3N4 could still form another heterojunction with CuO (possibly generated due to photocorrosion), so that the overall photo catalytic activity of the composite could be maintained to the most extent. Meanwhile, the degradation pathways of tetracycline and the global toxicity evolution were elucidated, which was important for the tetracycline related wastewater treatment with respect to minimizing the potential ecological risks.