Evaluating the influencing mechanism of solvents on the self-assembly synthesis of carbon nitride towards a high photocatalytic performance

Abstract

The micro-structure of photocatalyst is an underlying factor affecting its activity. This work aims to clarify and get an applicable knowledge concerning the influences of different solvents on the formation of carbon nitride (CN) with different microstructures. In this bottom-up preparation of CN, solvent with smaller molecule size and lower viscosity benefits the insertion, avoiding a bulk structure. Furthermore, solvent with stronger polarity tends to cause rough and irregular surface. The CN sample prepared using ethanol as solvent (CN-E) shows the lowest PL emission and the highest photocatalytic activity compared to its counterparts, owing to its ideal hollow structure with moderate aspect ratio. The results synergistically address that: 1) Solvent with smaller molecule size，lower viscosity and moderate polarity results in an ideal hollow microstructure; 2) this microstructure is beneficial to the mass transfer and further photocatalytic process; 3) light-harvesting and conversion efficiencies are greatly improved thanking to the multi-reflection of light brought by the hollow structure. It can be concluded that the photocatalytic activity of carbon nitride is closely related with its microstructure which can be effectively tuned through the use of solvents, and we expect that by establishing this correlation, applicable knowledge could be acquired and so as to apply.