This chapter explores how nanomaterials can be used in the CP of metals, by acting as photoanodes (in photoelectrochemical cell) and nanogenerators. Cathodic protection (CP) of metal refers to the use of an impressed direct current (DC from an external source) or a sacrificed anode, to reduce or eliminate the corrosion of metals (a cathode). This method has been widely used to protect the buried or submerged metallic structures. For the use of sacrificed anode, nanomaterial is not the material of choice because of its low density and high cost. Regarding the DC power sources, various types of sources can be used in the impressed current CP, such as rectifiers, batteries, engine generator (with fuel), thermoelectric generators, fuel cells, and solar cells. Nowadays, on the issue of energy and cost savings, these electric sources have been favorably generated from natural and renewable energy systems. In this regard, nanomaterials have been used to convert the mechanical/thermal/light energies into electricity in the CP of metals. © 2020 Elsevier Inc. All rights reserved.