Tuning interfacial charge transfer for efficient visible-light-driven photodegradation and simultaneous H₂ evolution

The edge-graphitized carbon nitride (C₃N_4[sbnd]C_g) was prepared by secondary pyrolysis to construct ZnO/C₃N_4[sbnd]C_g (ZCN) type-Ⅱ heterojunction photocatalyst via a facile sonication dispersion method, which achieved ∼7.04-fold and ∼18.3-fold enhanced visible-light-driven photocatalytic performance for refractory micropollutant removal and simultaneous hydrogen (H₂) evolution respectively compared to conventional ZnO/g-C₃N₄ Step-scheme heterojunction. The apparent quantum efficiency of the ZCN_0.4 heterojunction reaches 0.92% (λ = 420 nm). Such excellent performance stems from that the edge-graphene moieties stitched onto the interface of heterojunction extend light absorption to the full visible spectrum, meanwhile, the built-in electric field generated during Fermi level alignment accompanying favorable band-bending structure provides an effective pathway for the rapid migration of photoinduced electrons via the edge graphene channel to improve interfacial charge separation efficiency. Interestingly, the midgap states introduced in ZCN heterojunction could temporarily retain photoexcited electrons to effectively inhibit the in situ carrier recombination for improved photocatalytic H₂ evolution. Moreover, ZCN/peroxymonosulfate system exhibited excellent anti-interference performance against complex water bodies under visible illumination due to the synergistic effect between the co-existing anions and organic matter. Meanwhile, the eco-friendly nature of the ZCN/peroxymonosulfate system showed no biotoxicity of reaction filtrate on cell proliferation after treatment, which avoided secondary contamination. Considering the outstanding performance in photocatalysis, the ZCN system exhibits broad potential for practical applications in water pollution control and green energy production.