Interfacial engineering of g-C3N4/Cu2Mn3O8 heterostructure for enhanced visible-light photocatalytic performance

Abstract

The discharge of toxic organic dyes into aquatic environments necessitates efficient and sustainable photocatalysts. Herein, a g-C3N4/Cu2Mn3O8 heterostructure was synthesized hydrothermally through interfacial coupling for enhanced visible-light photocatalysis. XRD confirmed phase-pure monoclinic Cu2Mn3O8 integrated with g-C3N4, and FTIR verified the coexistence of the triazine and metal–oxygen frameworks. The heterostructure possesses a BET surface area of 83.9 m2 g−1 with mesopores of 7.54 nm, displays enhanced visible-light absorption with band-gap narrowing from 2.48 to 2.31 eV, quenched photoluminescence, and a lower interfacial charge-transfer resistance (7.31 Ω). Under visible light, 85% of Congo Red (CR) was degraded within 120 min versus 59% over pristine Cu2Mn3O8, while pristine g-C3N4 degraded 66% of Congo red under the same conditions; the apparent pseudo-first-order rate constant increases from 0.0076 to 0.0161 min−1 (R2 ≥ 0.94). Scavenger tests identify ˙O2− and ˙OH as the dominant reactive species, and ∼89% of the initial activity is retained over four consecutive cycles. These findings demonstrate that interfacial coupling promotes light harvesting and charge separation, making the g-C3N4/Cu2Mn3O8 heterostructure a highly effective visible-light photocatalyst for dye removal.