Exploring Graphitic Carbon Nitride Based Nano-Heterogeneous Photocatalysts for Elimination of Wide Range of Contaminants and Water Splitting

Abstract

Presently, contamination of waster with harmful and waste materials, leading to significant adverse effect on the environment and wildlife. Direct disposal of nonbiodegradable and undesirable chemical compounds into water makes it unsuitable for drinking and for other purposes. Hence, elimination of contaminants from wastewater has become an important issue, because of the adverse effects on human health and environment. Conventionally, various techniques including advanced oxidation, coagulation, adsorption, reverse osmosis, and ion exchange have been used to remove these hazardous pollutants from polluted water. Of these, photocatalysis purification based on heterostructures are one of the most prominent technologies in the direct use of solar energy for the degradation of wide range contaminants and production of H2; these are potentially the best promising green technologies that replace conventional energy resources. In order to achieve the desired efficiency, the photocatalysts should have an excellent light absorbance, rapid charge separation, and a high chemical stability. A great deal of effort has been devoted to enhancing the efficiency of the photocatalytic process and extending the light adsorption range of photocatalysts; these include formation of semiconductor nanoheterostructures, co-deposition of noble metals, and coupling with other technology. Among the various approaches, formation of nano-heterojunctions is a promising approach; it can induce band bending at the interface of junction resulting in a built-in field, which can drive the photogenerated electrons and holes to move in opposite directions. In our laboratory, we fabricated and investigated different nano-heterogeneous photocatalysts based on graphitic carbon nitride (g-C3N4) and its hybrids with aligned ZnO/TiO2 nanorods, ZnTiO3 nanofibers, Au nanoparticles and CNTs, and graphene nanosheets via solvothermal methods. The fabricated have been tested to degrade organic pollutants such as methylene blue, and rhodamine B have degraded under visible irradiation. In addition, we measured H2 evolution from water splitting under visible irradiation. The photocatalytic activities of nano-heterogeneous photocatalysts was seen to be better over the pristine structure. Improved performance was aroused from broadened the optical window, short diffusion distance for excellent charge transport, and increase contact area with supporting electrodes for rapid interfacial charge separation and transportation. Therefore, the present ternary graphene aerogel based nano-heterogeneous photocatalysts could be applicable in hydrogen production and water purification technology.