This book covers synthesis, characterization, and applications of diverse types of nanomaterials. Specifically, it describes carbon, graphene, and graphene oxide-based nanomaterials and their use for environmental remediation; rare-earth ions-activated nanophosphors and their application; lanthanide-based oxides as advanced nanostructured materials for organic decontamination; and advanced functional nanomaterials for pollutant sensing and water remediation. The chapters explore the use of nanomaterials in solid-phase extraction technique, design of colorimetric sensor based on gold nanoparticles, optical sources and waveguides based on flexible 1D nanomaterials, synthesis and property characterization of 2D materials with applications, and the scale effects on the value of the surface energy of a solid. The developments of some nanomaterials such as zinc and nickel sulfides as photocatalysts and electrocatalysts, effects of reducing size and incorporation of nanoadditives, advanced carbon nanomaterials such as carbon nanotubes, carbon nanofibers, and graphene and its derivations as adsorbents, and carbon spheres and carbon soot for tribological applications are also presented in this book. In addition, nanomaterials for concrete coating applications and advances in the processing of high-entropy alloys by means of mechanical alloying are also covered. Subsequently, the use of nanomaterials in endodontics and the use of nanotechnology strategies to enhance restorative resin-based dental nanomaterials are reported.