Constructing an Ohmic-like Type-I Heterojunction via Electrostatic Self-Assembly of Silver Cyanamide and g-C3N4 for Boosted Photocatalytic Performance

Developing efficient heterojunction photocatalysts for organic pollutant removal remains an important goal in water treatment. We prepared Ag2NCN/g-C3N4 (ACN) composites with different Ag2NCN loadings via electrostatic self-assembly. Under full-spectrum light, ACN-2 degraded 99 % of Rhodamine B within 30 min, with a rate constant 5.7 times that of pristine g-C3N4. It also exhibited good reusability and achieved 61.2 % total organic carbon removal. Mechanistic studies indicated that the composite forms an ohmic-like type-I heterojunction. The Fermi-level offset across the Ag2NCN/g-C3N4 heterojunction gives rise to a built-in electric field at the heterointerface, which facilitates directional charge migration from g-C3N4 toward Ag2NCN and effectively curbs carrier recombination. Superoxide anions (•O2–) and photoinduced holes (h+) served as the dominant reactive species. This work offers a straightforward route to type-I heterojunctions with improved charge separation through interfacial electric field engineering, and provides practical insights for designing effective photocatalysts for wastewater treatment.