An electrochemical perspective of solar redox flow batteries Gengyu Tian, Ana Sobrido, Rhodri Jervis, Joe Briscoe, Magdalena Titirici Queen Mary University of London, UK Here we have synthesised MoS 2 @ TiO 2 thin films supported on FTO glass substrate using a facile hydrothermal route, for their application as photoanode in a self-designed all-vanadium solar flow cell. The utilization of MoS 2 - covered TiO 2 photoanodes ensures an increased specific surface area and an effective light response, which translates into an enhanced photon and mass transport. Fig. 1 shows the enhancement in the photocurrent generated by our MoS 2 @TiO 2 versus bare TiO 2 thin film over time by EIS experiments. There are lot of information we can find by EIS characterization. The solar redox flow battery has an average of ~0.45 mA cm -2 for the MoS 2 @ TiO 2 versus 0.05 mA cm -2 for TiO 2 . When sunlight strikes the photoelectrode, the photogenerated holes oxidised V 4+ to V 5+ while the photogenerated electrons reduced V 4+ to V 3+ at the counter electrode (carbon felt). The oxidised form of V 5+ and reduced form of V 3+ thus retain the chemical energy and can be converted to electricity via a reverse reaction. The whole reaction can be summarized as TiO 2 /MoS 2 (s)|V 4+ , V 5+ ||V 4+ , V 3+ |Carbon Felt(s), E0=0.66V vs SHE. A preliminary capacity of 60 mAh l -1 was observed (Fig. 1c). This is the first time a MoS 2 @ TiO 2 photoelectrode has shown promising catalytic activity towards the V(IV)/V(V) redox pair. We have combined an all-vanadium redox flow battery with a photoelectrochemical cell in the solar flow cell, where vanadium redox species served as the energy storage media while photoelectrochemical reactions on a semiconductor converted solar energy into electrochemical energy [1] . References 1. Tian, G., Jervis, R., Briscoe, J., Titirici, M., Sobrido, A. J. ,J. Mater. Chem. A, 2022, 10 , 10484-10492
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