Visible-light-driven H2O2 production from O2 reduction with nitrogen vacancy-rich and porous graphitic carbon nitride

Abstract Visible-light-driven H2O2 production from O2 reduction is an eco-friendly strategy and attracts increasing attentions. In this study, KOH modified graphitic carbon nitrides (CNKx) were constructed through the thermolysis of melamine-cyanuric acid supramolecular-complex in the presence of KOH. The BET specific surface area of CNK0.2 with porous structure was 92 m2 g-1. The photocatalyst was characterized by using XPS, ESR and element analysis and the analysis suggested that nitrogen vacancy was created in the framework of g-C3N4. Photoluminescence (PL) spectra indicated that the recombination of photogenerated electrons and holes was efficiently suppressed. ζ-potential revealed that more negative charge on the surface of CNK0.2, which promoted the adsorption of O2 and accelerated the photocatalytic H2O2 production. ESR experimental and radical quenching results illustrated that superoxide radical (O2- ) was the primary intermediate during the O2 reduction process, suggesting the O2 reduction pathway by CNK0.2 was the sequential two-step single-electron reduction.