14 - Graphene-based polymer composites for photocatalytic applications

Abstract

Thanks to the permanent progress of science and technology, the living conditions of most people in the world have been greatly improved over the last few decades. The demands are growing day after day and the increase in industrial and domestic energy consumption to satisfy these demands leads to a threat of a shortage of natural resources. Today, the use of fossil energy sources (coal, oil, and gas) is the origin of carbon dioxide (CO2) gas release, which contributes to the global warming of the Earth. The consequences of climate changes are multiple: violent storms, heatwaves, loss of snow cover, and rising sea level. In addition, industrial and domestic wastes are mostly responsible for the contamination of soil, water (rivers, oceans), and air and the pollutants can release highly toxic products (heavy metal ions, organic dyes, pesticides, pharmaceuticals) that in turn, by their degradation, contaminate the biota. To face these problems, renewable or green energy sources (solar, wind, ocean) are progressively developed to replace fossil energies, and solar energy is the most promising resource since it is abundant and is available anywhere on earth. Despite these progresses, the pollution of the environment is still a problem to be solved for the well-being of society, especially the destruction of pollutants, which can affect directly human health. In this chapter, we shall focus on the applications of graphene in the field of photocatalysis and in particular, on the treatment of pollutants. We shall review the photocatalysis principle, which is the basic process using solar energy to degrade pollutants for the remediation of the environment. We present the different strategies for improving the performance of photocatalysis of materials and introduce the use of graphene and its derivatives in composites to address and solve the environmental research challenges. We then discuss the mechanisms of degradation of pollutants including organic dyes and carbon dioxide among others, by the graphene-based composites, and compare the performance of these materials to that of commonly and widely used photocatalysts, especially titanium dioxide (TiO2).