Graphitic carbon nitride modified with trace-level copper and carbon dots exhibits excellent photo-Fenton catalytic activity with low consumption of H2O2

Graphitic carbon nitride (g-C3N4) is a competent candidate for heterogeneous Fenton catalysis application. However, g-C3N4 based heterogeneous Fenton catalysts suffer from either high consumption of H2O2 or inefficient catalytic efficiency. In this work, g-C3N4 modified with trace-level copper and carbon dots (CDs) was designed. Contrary to previous understanding, the results revealed that the introduction of Cu decreased the photodegradation activity of g-C3N4 owing to the trapping of photogenerated charge carriers by introduced Cu species. But delightedly, the g-C3N4 modified with trace-level Cu (Cu-g-C3N4) not only exhibited exceptional Fenton-like catalytic activity with low consumption of H2O2 (4 mM), but also showed favorable photo-Fenton synergistic catalytic activity. The excellent performance was fundamentally due to the introduced trace-level Cu that avoided producing excessive defects acting as trapping centers of active radicals and simultaneously reduced the consumption of photogenerated charge carriers by Cu species themselves, giving rise to more active radicals and highly efficient utilization of H2O2. Moreover, after introducing CDs, the obtained CDs/Cu-g-C3N4 showed higher photo-Fenton activity in degrading different organic pollutants compared to Cu-g-C(3)N(4 )owing to the role of CDs in facilitating the charge transfer and strengthening the interaction with organic pollutants. The constructed Cu-g-C(3)N(4 )and CDs/Cu-g-C3N4 showed wide application pH and high stability, holding great potential in practical pollutants degradation applications.