Renewable energy sources are the cornerstone of a sustainable future in today’s modern world. With a rapid increase in population, the world is facing a severe energy shortage. Therefore, industrial and domestic sectors are working together to address the huge demand for energy in the form of electricity. Storage devices, such as capacitors and batteries are losing their grip due to their shortcomings, despite the somewhat energy-driven technology requirements.
Supercapacitors are attracting unparalleled attention due to their weight, high power density, rapid charge-discharge capability, long cyclic ability, and robustness. Electrode materials are an important factor in increasing the electrochemical performance of Supercapacitors. In recent years, binary and ternary metal oxides are excellent electrode materials due to their promising properties such as their electrochemical performance and electrical conductivity. On the other hand, sulfides are excellent pseudocapacitive material, especially for their multiple redox reactions, improved electrical conductivity, low band gap, which leads to superior performance, better oxidation state, and longer cycling compared to metal oxides/ hydroxides. So, extensive interest has been paid to form quaternary chalcogenides and rare-earth based metal oxide composites by the suitable incorporation of the carbon-based material to retain the stability.
Other than Supercapacitors, another type of capacitor that allows direct storage of solar energy is the ‘photocapacitor’. As the name indicates, the capacitor captures the solar energy directly during the peak time and stores it in the form of electrical energy. This process is called charging. Moreover, this stored energy is used during the nighttime and this process is called discharge. A novel photocapacitive system where semiconducting material is employed as the photoactive core to generate electrons and holes by absorbing solar radiation. The photogenerated holes are subsequently stored in a capacitive layer. This storage stand is obtained through photo-oxidation of the capacitive layer. The combination of both, semiconducting material and capacitive layer provides a singular hetero-structured system capable to convert and store solar energy without applying any electrical bias under solar illumination.