Photo-Supercapacitors: Solar Energy Conversion and Storage Devices

Abstract

Access to clean and sustainable energy sources is one of the most important needs of human beings. Because energy-related problems directly affect every aspect of our lives, from education to health. Global warming and other environmental problems, the effects of which we see dominantly in the current period, are largely due to the use of fossil fuels in energy production. Therefore, in line with the Paris Agreement, it is necessary to achieve zero carbon emissions to keep global warming below 2 oC. This goal will only be possible with the use of renewable energy sources in every aspect of our lives. Undoubtedly, the sun can meet all the energy we need. With this potential, it is indisputably the most important among other renewable energy sources. The most important limitation of solar energy is that it is not always accessible. Therefore, storage systems are needed. To date, solar rechargeable battery systems and flow batteries using redox chemistry have been tried to be developed for this purpose. However, a new device comes to the fore, especially in meeting the energy needs of portable and autonomous systems. This device is called a photo-supercapacitor (PSC) and getting attention since the beginning of the 2000s. PSC, which mostly consists of a combination of dye-sensitized solar cells with supercapacitors, provides direct storage of electricity obtained from solar energy. However, in new generation energy conversion and storage devices, instead of producing and integrating two separate devices, double-acting, simpler and cost-effective solutions using electrodes that both absorb solar energy and store the generated electricity should be offered. At this point, composites of metal oxide nanoparticles prepared together with 2D materials show great potential. Due to the very long charge relaxation time of graphene oxide (GO)/zinc oxide (ZnO) nanostructure, we demonstrated the UV and day-light chargeable supercapacitors. and boosts the electrochemical properties of ZnO. GO easily captures photogenerated electrons and stores them in the large π-π network, enhancing the capacitive behavior of ZnO. This presentation reviews the recent advancements in PSC devices and dual-acting electrodes and their performance reported by our research group.