Integration of Atomically Dispersed Cu–N₄ Sites with C₃N₄ for Enhanced Photo-Fenton Degradation over a Nonradical Mechanism

Photo-Fenton degradation as a promising strategy for antibiotic wastewater treatment attracted extensive attention, while the unsatisfactory catalytic performance vitally limits its industrial application. Herein, we demonstrate that confining atomically dispersed Cu into C3N4 (Cu–C3N4) enables fast H2O2 activation and efficient separation of photogenerated electron–hole pairs, resulting in a dramatic improvement of the degradation efficiency of the Photo-Fenton reaction. Photo-Fenton degradation of ciprofloxacin (CIP) was close to 99% within 30 min over optimized Cu–C3N4, corresponding to a pseudo-first-order rate constant of ∼0.0978 min–1, almost 4.5 times higher than pure C3N4 counterpart. The electron paramagnetic resonance, quenching experiments, and X-ray absorption fine structure results reveal that the superior Photo-Fenton catalytic performance is attributed to a nonradical reaction pathway, where the H2O2 is activated by the formation of the O═Cu–N4═O intermediate. The advanced catalyst as well as the refreshing H2O2 activation mechanism are of profound significance for the materials design in the wastewater treatment field.