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

Graphitic carbon nitride (g-C3N4) is an emerging photocatalyst for treatment of organic pollutants. However, pristine g-C3N4 exhibits poor photocatalytic activity due to the inefficient generation of reactive species. Here, chemically multi-modified g-C3N4 was prepared through a facile thermal polymerization approach. The S, K-doped/alkalized g-C3N4 product can generate singlet oxygen (1O2) 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-C3N4 reaches 0.61 h−1 at pH 8 under visible-light irradiation, 4.1 times of pristine g-C3N4. As alkaline generation of ·OH is unfavorable, 1O2 could be a more reliable oxidative specie for degradation of pollutants in alkaline waters. Furthermore, taking advantage of the selective oxidation nature of 1O2, 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 1O2 as the active oxidative specie.