Synergistically effective and highly visible light responsive SnO2-g-C3N4 nanostructures for improved photocatalytic and photoelectrochemical performance

This paper reports the facile and scalable fabrication of mesoporous and high surface area tin oxide and tin oxide-graphitic carbon nitride nanostructures {SnO2, SnO2-C3N4 (2 mM) and SnO2-g-C3N4 (4 mM)} using a template-free hydrothermal approach. The overall characterisation revealed a high surface area (similar to 181 m(2)g(-1)) with a mesoporous nature, relatively small particle size of SnO2 (similar to 2-3 nm) grown successfully on g-C3N4 sheets, and significantly improved optical behaviour for visible light utilisation. Comparative screening of different SnO2-based nanostructures revealed significant improvements in visible-light induced photocatalytic degradation and photoelectrochemical performance. The visible light-induced degradation of model pollutants, such as Methylene blue (MB) and Congo red (CR), was achieved using SnO2-g-C3N4 (4 mM) with total efficiencies of similar to 99.38% and 96%, respectively. The optimal SnO2-g-C3N4 (4 mM) as a photocatalyst showed first order rate constants for MB and CR degradation of 6.39 x 10(-2) min(-1) and 2.9 x 10(-2) min(-1), respectively. Moreover, the investigation of different modified photoelectrodes of SnO2-g-C3N4 (4 mM) and SnO2-g-C3N4 (2 mM) show more than eight and five times higher photoelectrochemical performance than that of SnO2, respectively. The possible synergistic effect makes the SnO2-g-C3N4 (4 mM) nanostructure an exceptional photocatalytic and photoresponsive material under visible light that can be used for future environmental and energy-related purposes.