Efficient generation of singlet oxygen on modified g-C3N4 photocatalyst for preferential oxidation of targeted organic pollutants

Abstract

• A simple one-step method has been developed to chemically modify C 3 N 4 . • The modified C 3 N 4 can be used for efficient degradation of organic pollutants. • Singlet oxygen is the dominant active oxidative specie generated on modified C 3 N 4 . • Preferential oxidation of target organic pollutants is achieved with modified C 3 N 4 . • This work highlights the application of singlet oxygen generated in photocatalysis. Graphitic carbon nitride (g-C 3 N 4 ) is an emerging photocatalyst for treatment of organic pollutants. However, pristine g-C 3 N 4 exhibits poor photocatalytic activity due to the inefficient generation of reactive species. Here, chemically multi-modified g-C 3 N 4 was prepared through a facile thermal polymerization approach. The S, K-doped/alkalized g-C 3 N 4 product can generate singlet oxygen ( 1 O 2 ) efficiently. This powerful yet selective oxidant is found to be effective for the oxidation of bisphenol A (BPA). The degradation rate of BPA on S, K-doped/alkalized g-C 3 N 4 reaches 0.61 h −1 at pH 8 under visible-light irradiation, 4.1 times of pristine g-C 3 N 4 . As alkaline generation of · OH is unfavorable, 1 O 2 could be a more reliable oxidative specie for degradation of pollutants in alkaline waters. Furthermore, taking advantage of the selective oxidation nature of 1 O 2 , preferential treatment of targeted organic pollutants becomes possible. Such an approach can prevent the production of undesirable toxic intermediates which may be inevitable during · OH-based photocatalysis. This study provides a novel photocatalytic approach for preferential oxidation of targeted compounds in a complex matrix by using 1 O 2 as the active oxidative specie.