A Novel NH ₄ Cl‐C ₃ N ₄ /BiOCl Heterostructure for Efficient Photocatalytic Degradation of Rhodamine B and Ciprofloxacin

ABSTRACT Herein, a porous NH 4 Cl‐C 3 N 4 /BiOCl heterojunction is constructed via a facile two‐step route: NH 4 Cl‐assisted thermal exfoliation of g‐C 3 N 4 and the subsequent in situ deposition of BiOCl nanosheets. The 270NH 4 Cl‐C 3 N 4 /BiOCl composite, selected as the optimal photocatalyst, displays Rhodamine B (RhB) degradation rate constants that are 39‐fold higher than those of pristine g‐C 3 N 4 and ninefold greater than those of BiOCl. The corresponding constants for ciprofloxacin (CIP) exceed those of g‐C 3 N 4 and BiOCl by a factor of 28 and 3, respectively. The robust activity (90.0% retention after five cycles) and sunlight‐driven operation within minutes highlight its practical potential. Comprehensive characterization reveals that the thermal decomposition of NH 4 Cl generates gases in situ, and their violent release directly enlarges the specific surface area and creates abundant mesopores, intensifying light harvesting and providing rich active sites. The cooperative promotion of photon harvesting within the visible spectrum and efficient segregation of photogenerated carriers was realized through interfacial heterojunction construction and enlarged surface area, which has been confirmed by SEM, TEM, BET, DRS, PL, RIS, and photocurrent response. In addition, radical‐scavenging investigations conducted throughout RhB degradation demonstrate that h + is the dominant oxidative species, whereas •O 2 − and •OH fulfill a secondary function. This was further confirmed by band gap analyses and Mott Schottky. This study presents a straightforward and efficient approach for modulating 2D carbon‐nitride architectures and provides insights for designing high‐performance heterojunction photocatalysts.