Interface‐Engineered Z‐Scheme CuX/g‐C ₃ N ₄ (X = S, Se, Te) Nanocomposites for Synergistic Solar‐Driven Pollutant Degradation and Hydrogen Evolution

ABSTRACT Copper chalcogenides (CuX, where X = S, Se, Te) and their heterostructures with graphitic‐carbon nitride (g‐C 3 N 4 ) were successfully synthesized via a facile wet‐chemical approach and systematically characterized to establish structure‐property‐activity correlations. XRD and ATR‐IR confirmed phase purity, while XPS, FESEM/TEM, and elemental mapping revealed uniform distribution of CuX on g‐C 3 N 4 nanosheets. UV–vis–DRS analysis demonstrated broadened visible‐light absorption with narrow‐bandgaps (CuSe/g‐C 3 N 4 : 2.37 eV vs pristine g‐C 3 N 4 : 2.59 eV). PL‐quenching and electrochemical‐impedance studies confirmed suppressed charge‐recombination and enhanced carrier‐dynamics in the composites. Photocatalytic performance was evaluated for RhB dye degradation and hydrogen evolution under simulated sunlight. Pristine g‐C 3 N 4 exhibited only 40% dye degradation in 180 min but achieved a hydrogen evolution rate of 149.4 µmol g −1 h −1 . Conversely, CuSe alone degraded 72% of RhB but showed limited H 2 evolution (56.4 µmol g −1 h −1 ). Notably, the CuSe/g‐C 3 N 4 heterostructure achieved 95% RhB‐degradation, representing an oxidation‐dominated process, and delivered a hydrogen evolution rate of 173.5 µmol g −1 h −1 , corresponding to a reduction‐dominated process, both outperforming pristine g‐C 3 N 4 . Scavenger studies identified h + and •OH as the dominant reactive‐species, while Mott–Schottky analysis revealed a Z‐scheme mechanism facilitating efficient charge‐transfer and high redox‐potential. These results highlight CuX/g‐C 3 N 4 heterostructures as multifunctional photocatalysts for solar‐driven hydrogen‐production and environmental remediation.