Efficient Harvesting and Storage of Solar Energy of an All-Vanadium Solar Redox Flow Battery with a MoS2@TiO2 Photoelectrode

Solar redox flow batteries constitute an emerging technology that provides an intelligent alternative for the capture and storage of discontinuous solar energy through the photo-generation of the discharged redox species employed in traditional redox flow batteries. Here, we show that a MoS₂-decorated TiO₂ (MoS₂@TiO₂) photoelectrode can successfully harvest light stored in a solar redox flow battery using vanadium ions redox-active species in both catholyte and anolyte, and without the use of any bias. MoS₂@TiO₂ photoelectrode achieved an average photocurrent density of ~0.4 mA cm^-2 versus 0.08 mA cm^-2 for bare TiO₂ when tested for the oxidation of V⁴⁺ to V⁵⁺, attributed to a more efficient light harvesting and charge separation for the MoS₂@TiO₂ relative to TiO₂. The designed solar redox flow cell exhibited an optimal overall solar-to-chemical output energy conversion efficiency (SOEE) of ~4.78%, which outperforms previously reported solar redox flow batteries. This work demonstrates the potential of MoS₂@TiO₂ photoelectrode to efficiently convert solar energy into chemical energy in a solar redox flow battery, and it also validates the great potential of this technology to increase reliability in renewable energies.