Chapter 12 - Magnetically retrievable graphitic carbon nitride-based nanocomposites

Abstract

Fast industrialization of societies and the dependence of these industries on fossil fuel resources have exacerbated the universal energy crisis and increased the environmental problems. Thus, the development of renewable energy sources to replace with fossil fuels and the treatment of industrial wastewaters to decrease the harmful effects of pollutants on the environment have attracted considerable scientific attentions. Recently, heterogeneous photocatalysis has received significant attentions in green chemistry and in emerging “Advanced Oxidation Processes” (AOPs) to tackle energy and environmental crises. Semiconductors are the basis of heterogeneous photocatalytic processes, thanks to their suitable bandgap energies, light harvesting capability, and charge transferring properties. As a promising candidate, a metal-free polymeric semiconductor, namely graphitic carbon nitride (g-C3N4), has engrossed a lot of attentions due to its great stability, environmental friendliness, ability to harvest visible irradiation, and facile synthesis from inexpensive N-rich precursors. However, different drawbacks such as the rapid recombination of the carrier charges, small specific surface area, and inefficacious visible-light utilization confined the photocatalytic activity of pure g-C3N4. Thus, different approaches have been developed to tackle these limitations like energy band engineering, coupling with other semiconductors, doping with metal or nonmetal elements, controllable preparation of nanosized morphologies, and designing various nanostructures. Moreover, loss of photocatalyst and secondary contamination by photocatalyst particles are some of the problems facing photocatalytic processes. The separation and recycling of the powdered photocatalysts from the reaction solution are extremely difficult. Integration of photocatalysts with magnetic materials will be helpful for separation of them from treated systems via an external magnetic field. These hybrid materials have been considered as a novel type of photocatalysts, namely magnetically recoverable photocatalysts. This chapter presents the recent progress in preparation and application of the magnetically separable nanocomposites based on g-C3N4.