Nanomaterials are becoming a research area because they are used in many fields of application, such as agriculture, green technology, artificial intelligence, pollution reduction, nanotechnology, and controlling global warming. The properties of nanomaterials vary depending on their size. This chapter reviews the nanomaterial’s remarkable characteristics, which majorly influence the remediation process to avoid environmental pollutants. One of the main causes of climate change is pollution. The planet suffers from the effects of pollution in the air, water, and soil, which renders the environment unsuitable for human habitation. These include a variety of illnesses (cancer, respiratory and skin conditions, etc.), acid rain, global warming, ozone depletion, and climate change. Nanoparticles (NPs) have been widely used in the remediation of hazardous wastes. In this chapter, we focus on the many biological origins of NPs and their role in the remediation process to reduce the environmental impact of hazardous wastewater. This chapter discusses some specific nanoparticles’ photocatalytic capabilities, including metal-doped cerium, Fe-doped cerium, Mn-doped CeO2, and CeO2/Ag3PO4 nanocomposites.