Maleic hydrazide-based molecule doping in three-dimensional lettuce-like graphite carbon nitride towards highly efficient photocatalytic hydrogen evolution

A three-dimensional (3D) lettuce-like g-C3N4 with maleic hydrazide-based molecule doping was successfully developed. Based on systematic physicochemical characterizations and density functional theory (DFT) calculation, it was found that the diazine organic groups of maleic hydrazide, which occupied the positions of partial tris-triazine units, participated in the construction of valence band maximum (VBM) and promoted the formation of effective charge transfer channel from the diazine organic group in maleic hydrazide to the adjacent tris-triazine unit to promote the generation and separation of photo-generated carriers. Meanwhile, the 3D lettuce-like microstructure constituted by thin g-C3N4 nanosheets could shorten the migration distance of carriers to further inhibit the recombination of photo-generated carriers, and also bring the ultrahigh surface area to provide more active sites for photocatalytic reaction. The superior visible-light-driven photocatalytic H-2-evolution activity was obtained (7689.6 mu mol h(-1) g(-1)), which was 31.5 times that of unmodified g-C3N4, and the apparent quantum efficiency was up to 8.53 % at 425 nm.