Modulating the photooxidation selectivity on graphitic carbon nitride by tuning edge functional groups

Abstract

Selective photooxidation reactions offer a promising route for transformation of organic pollutants into high-value products under mild conditions. In this work, we demonstrate that the edge functional groups in polymer carbon nitride (PCN) were key to the selectivity of methyl mercaptan (CH3SH) photocatalytic oxidation. The amino-decorated PCN favors the oxidation of the -SH group of CH3SH to forming CH3SO3H with selectivity up to 84.0%, while cyanamide-enriched PCN prefers to breaking the -CH3 end of CH3SH and produce H2SO4 with selectivity of 82.0%. The totally difference in reaction sites is ascribed to the functional-group-modulated electronic structure of PCN, which determines activity of photoinduced carriers and the molecular oxygen activation pathway. The amino- and cyanamide-decorated PCN leads to preferential generation of 1O2 and·O2-, respectively. This study highlights the significant role of edge groups engineering in modulation of the excitonic effects in PCN and the resultant selectivity control during photocatalytic reaction.