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 (O-1(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-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, O-1(2) could be a more reliable oxidative specie for degradation of pollutants in alkaline waters. Furthermore, taking advantage of the selective oxidation nature of O-1(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 photo catalytic approach for preferential oxidation of targeted compounds in a complex matrix by using O-1(2) as the active oxidative specie.

Automated summary

Graphitic carbon nitride (g-C3N4) is a promising photocatalyst for organic pollutant treatment. This study successfully enhanced the photocatalytic activity of g-C3N4 through chemical multi-modification. The S, K-doped/alkalized g-C3N4 product efficiently generates singlet oxygen (O-1(2)) and selectively oxidizes bisphenol A (BPA) for degradation.