Tracking the chemical active species to unravel the photocatalytic activity evolution of structure modified polymeric carbon nitride

Abstract

Herein, a series of structure modified polymeric carbon nitride (PCN) started from the same precursor were prepared by a step-by-step method. The photocatalysts show different catalytic performance in degradation of Rhodamine (RhB) and methyl orange (MO). The doping treatment endows photocatalysts improved activity for decomposing RhB molecules. Subsequently heterojunction formation by incorporation of Ag-related species facilitates the degradation of the MO molecules, but it seems like at the expense of the activity of RhB molecules decomposition. By combining studying the evolutions of micro-structure, electronic structure, and spatial charge separation of each sample, we found that the photoluminescence reflected spatial charge separation effect cannot be used to fully explain aforementioned trends of the photocatalytic activity. In this background, we systematically studied the roles of each individual active species that influenced photocatalytic performances for each sample, and a reasonable degradation mechanism on the basis of roles of different active species is proposed to interpret the above photocatalytic phenomena in detail. Furthermore, we believe that this work not only presents a facile route to modify catalyst for enhancing photocatalytic performance, but the more important is that, it reveals the enhancement mechanism from the viewpoints by combining both effective charge separation and proportion evolution of active species.