Carbonaceous Composites of Rare Earth Metal Chalcogenides

The emerging environmental crisis has prompted humans to develop clean and renewable energy generation systems along with storage facilities possessing outstanding performance. Supercapacitors (SCs) have been widely explored because of their high power density and a large number of cycles compared with batteries. In general, rare earth metals are a group of trivalent elements possessing excellent characteristics. Chalcogenides of rare earth metals and their carbonaceous composites have been given significant attention due to their diverse oxidation states, specific surface texture, and higher volume to mass ratio, and fascinating electrochemistry. These properties endow carbonaceous composites of rare earth-based chalcogenide with a huge possibility of utilization in electrical energy storage equipment such as batteries and SCs. Lanthanum oxide (La₂O₃) nanoparticle anchored on rGO nanosheets by hydrothermal method achieved capacitance of 889.29 F cm⁻² compared to 67.47 F cm⁻² of La₂O₃. Also, GO/Sm₂S₃ composite thin films achieved capacitance of 360 F g⁻¹ which is approximately sixfold that of Sm₂S₃. These two representative examples indicate the need to enlighten the preparation methods and the supercapacitive performance of the rare earth composite materials. This chapter presents a general description of the synthesis methods of composites of carbon allotropes and rare earth metal chalcogenides. The development and improvement in their structural, morphological, and electrochemical properties are highlighted. Finally, electrochemical properties of the SC devices based on these composite materials are discussed.