Template-free synthesis of 2D porous ultrathin nonmetal-doped g-C3N4 nanosheets with highly efficient photocatalytic H2 evolution from water under visible light

The novel two-dimensional (2D) porous ultrathin oxygen-doped g-C3N4 nanosheets (PUOCNs) were prepared. The comprehensive characterization methods were used to study morphology, microstructure, crystal structure, chemical states and photocatalytic performance of PUOCNs. 2D porous ultrathin structure and the introduction of oxygen are beneficial to the enhancement of the photocatalytic activity of PUOCNs. The average H-2 evolution rate of PUOCNs is similar to 189.3 mu mol h(-1), which is similar to 5.2 times higher than that of the bulk g-C3N4 and the degradation efficiency of organic dye methyl orange (MO) is almost 71 times higher than that of the bulk g-C3N4. The enhanced photocatalytic activity is due to the more adsorption sites and more active sites, the enhanced redox ability and improved electron transport ability, which leads to less recombination and a more efficient separation of photogenerated electron and hole pairs. Through XPS VB and ESR analysis, the photocatalytic mechanism was also researched in detail. (C) 2015 Elsevier B.V. All rights reserved.