Sulfur mediated graphitic carbon nitride/S-Se-graphene as a metal-free hybrid photocatalyst for pollutant degradation and water splitting

Development of metal-free catalysts is of huge interest for photocatalytic water splitting using solar energy. Here, we report a composite nano-material consisting of sulfur-incorporated graphitic carbon nitride grown on the surface of sulfur/selenium co-doped graphene (CNS:S-Se-Gr) hybrid as a high-performance metal-free photocatalyst for the degradation of methylene blue (MB) and hydrogen evolution (by water splitting) in the presence of sacrificial donors under visible light illumination. The recorded MB degradation efficiency is about 98% in 3.5 h. The achieved highest hydrogen evolution rates for CNS:S-Se-Gr hybrid in sodium sulfite and lactic acid solution are about 1.58 and 2.59 mmol g(-1) h(-1) respectively. This hybrid material exhibits significantly enhanced photocatalytic H-2 evolution activity (9-fold) compared with that of pristine g-C3N4. Also, we proposed a possible mechanism for charge separation and transfer in the CNS:S-Se-Gr catalyst. Additionally, modulation of the electronic band structure has been investigated. These results suggest that the CNS:S-Se-Gr metal-free hybrid has great potential as a promising photocatalyst for the water splitting. (C) 2015 Elsevier Ltd. All rights reserved.