Unraveling highly efficient nanomaterial photocatalyst for pollutant removal: a comprehensive review and future progress

The presence of pollutants in the environment harms the living organism. Photocatalytic technology has been considered as one of the efficient methods for pollutant removal. Photocatalysis is a process that converts abundantly available photonic energy into useful chemical energy. Nanostructured photocatalysts have gained attention in various applications such as removal of organic pollutants, reduction of the level of contaminations arising out of heavy metals, purification of water, and evolution of hydrogen as they possess multiple benefits such as improved light-harvesting efficiency, low charge recombination, and accelerated surface reactions. The foremost goal of such photocatalysis-based technologies is to synthesize an efficient photocatalyst material with high catalytic efficiency and energy harvesting capability in light spectra such as ultra-violet (UV) or visible regions. This article provides an extensive review of different photocatalytic materials that are activated in UV or visible light irradiation for pollutant removal. Special attention is paid to metal oxides, chalcogenides, chalcohalides, perovskites, carbon-based materials, and metal-organic frameworks (MOFs), which are considered active photocatalyst materials. This review article summarizes the recent achievements in the photocatalytic removal of harmful contaminants using a wide range of materials from the most explored inorganic compounds to novel heterostructures as well as hybrid inorganic-organic structures. Moreover, the influence of different factors, including material morphology, surface area, optical properties, and material doping on photocatalytic activity is discussed in detail in this article. Finally, the prospects in new catalyst design, preparation, and modification are proposed to overcome the significant problems existing in the field of modern photocatalysis.