Nitrogen Vacancy-Engineered Copper-Loaded g-C ₃ N ₄ for Enhanced Photo-Fenton-Like Activity: Synergistic Electron Trapping and Migration Mechanism

In the heterogeneous photo-Fenton-like system, enhanced separation and migration of photogenerated charge carriers can further accelerate the redox cycle of metal ions and promote both H 2 O 2 activation and the generation of reactive oxygen species (ROS). In this work, copper-loaded carbon nitride with nitrogen vacancies (Cu-Nv-CN) was synthesized. Cu-Nv-CN exhibits outstanding heterogeneous photo-Fenton-like activity, 94.0% of tetracycline (TCH) is eliminated within 50 min in the presence of 10 mM H 2 O 2, and the corresponding degradation rate constant reached 0.0522 min –1 . Surface photovoltage and femtosecond transient absorption (TA) spectroscopy measurements revealed that Cu sites act as effective electron trapping centers. Furthermore, the introduction of Nv drives the rapid migration of photogenerated electrons to the Cu sites. The synergistic interplay between these two factors significantly improves the utilization efficiency of photogenerated charge carriers. The photo-Fenton-like pollutant degradation mechanism of Cu-Nv-CN was systematically elucidated by combining radical trapping experiments, electron paramagnetic resonance (EPR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) measurements. This study proposes a viable strategy for boosting the catalytic activity of graphitic carbon nitride-based photocatalysts in advanced photo-Fenton-like systems.