Visible-light-driven N2-g-C3N4 as a highly stable and efficient photocatalyst for bisphenol A and Cr(VI) removal in binary systems

Abstract Proper design and preparation of photocatalyst with higher stability, higher activity and lower cost is still a significant objective. It is critical to know how it works. In this work, N 2 -g-C 3 N 4 was fabricated via a facile approach for the oxidation of bisphenol A (BPA) and reduction of hexavalent chromium (Cr(VI)) synchronically in BPA/Cr(VI) binary systems under visible light irradiation (λ ≥ 420 nm). The resulting N 2 -g-C 3 N 4 performed much higher removal efficiency in binary systems than in single system owing to the synergistic effect between BPA oxidation and Cr(VI) reduction. Moreover, the free-radical quenching experiments and hydrogen peroxide (H 2 O 2 ) generation in different dispersions were performed to research the mechanism, and the results suggested that Cr(VI) can be reduced to Cr(III) by the generated H 2 O 2 and conduction band (CB) electrons. O 2 − radicals dominated BPA degradation and derived mainly from the reaction between CB electrons and adsorbed oxygen as well as interaction of Cr(VI) and H 2 O 2 , which was verified by electron spin resonance (ESR) active species trapping experiments. These results of BPA oxidation and Cr(VI) reduction in binary systems and the corresponding reaction mechanism analysis might consolidate the fundamental theories of photocatalytic reactions for real environmental pollution cleanup applications.