Light-powered flow cell established

In the first flow cell architecture the 0D NCPC-based electrode is coupled to the GQDs dispersion (acting as the catholyte). The other compartment will be based on electrodes used to carry out the redox reactions in electrolytes based on redox active small organic molecules such as viologens, antraquinones, phenazynes, etc. The two-compartment assembly can be realized using a horizontally mounted, double compartment, photo-electrochemical H-cell with electrolyte input/output ports, as well as compact no-gap serpentine architecture. The latter, typically including graphite flow-field layout-based graphite bipolar plates, teflon flow frames, rubber gaskets and metal-plated end plates with electrolyte input/output ports will be modified to create a compartment based on an end plate directly given by transparent 0D NCPC-based electrode. Peristaltic pumps will be used to flow the electrolyte into the cell hardware. Besides, light-driven electrolytic capacitor will also be fabricated by assembling two capacitor-type electrodes (e.g., activated carbon, graphene) by solid-state GQD-containing electrolytes.High-frequency resistance of the system will be measured by electrochemical impedance spectroscopy to exclude possible series resistance effects, thus determining iR-corrected polarization curves specifically resulting by kinetic losses. Galvanostatic charge discharge measurements of the systems will be carried out at different current densities, which will be selected on the basis of the polarization curve results. Solar-driven charge will be investigated by coupling a light source to the flow cell and illuminating the transparent electrode while monitoring the obtained photocurrent and photovoltage. Experiments with electrolytes having different concentration of redox-active materials and being initially charged at different states of charge (SOC) will be performed to investigated the efficiency of the solar-driven flow batteries as a function of the electrolyte composition. The light storage efficiency will be calculated as the ratio between the stored energy density in the system and the energy of the incident light. Additionally, coulombic efficiency (i.e., the ratio between discharge capacity and the charge capacity), the voltage efficiency (i.e., the ration between the average voltage during discharging and the average voltage during charging), as well as the energy efficiency (i.e., the product between the coulombic efficiency and the voltage efficiency), will be determined by the charge/discharge curve analysis. For the overall flow-driven system, the “overall” energy conversion efficiency will be determined by the product between the charge storage efficiency and the energy efficiency.