Ionic Liquid Assisted Construction of B and P Double Doped 3d Porous G-C3n4 and Photocatalytic Hydrogen Production Under Visible Light

By using melamine and melamine as precursors, 1-ethyl-3-methyl-imidazolium tetrafluoroborate [Emin]BF 4 and 1-butyl-3-methyl-imidazolium hexafluorophosphate [Bmim]PF 6 as boron and phosphorus sources, the N-type B and P double doped 3D porous g-C 3 N 4 (CN-B-P) was successfully prepared. The reason for obtaining 3D porous structure is that the raw material is decomposed at high temperature to produce gas molecular etching materials such as CO 2 and NH 3 to form porous structure during high temperature calcination. The formed 3D porous structure provided a larger specific surface area, and the specific surface area of the best sample (CN-45B-45P) reaches 137.49 m 2 g −1 . A larger specific surface area and porous structure are conducive to providing more active sites for the reaction, shortening the electron transfer path and accelerating the electron transfer efficiency. Under the influence of B and P doping and the formation of 3D porous structure, the hydrogen production rate of CN-45B-45P reached 9443.38 μmol/g/h, which was 12.34 times that of bulk carbon nitride CN (765.17 μmol/g/h), and was also better than that of the best sample (N-CN-45B-45P) without platinum as a cocatalyst (1187.34 μmol/g/h). In addition, the cyclic and continuous hydrogen production test results show that the sample has excellent stability and durability.