Construction of Fe2O3-CuO Heterojunction Photoelectrode for Enhanced Efficiency of Solar Redox Flow Batteries

To address the problem of suboptimal performance in deep eutectic solvents displayed by traditional TiO2 photoelectrodes and Cu2O photoelectrodes that have undergone simplistic modifications that result in a mismatch with battery discharge capacity, a method combining hydrothermal and dip-coating techniques was developed to create a Fe2O3-CuO heterojunction structure on the FTO surface. Then, the impact of the heterojunction structure on the performance of solar flow batteries was investigate in this study. The experimental findings reveal that the formation of the heterojunction structure effectively mitigates the recombination rate of photogenerated carriers within the photoelectrode. Furthermore, by meticulously adjusting the CuO loading, the harmonious balance between charging and discharging currents was achieved, thereby enhancing the overall performance of the solar redox flow batteries. In comparison to standalone Fe2O3 photoelectrodes, this innovative approach significantly broadens the spectrum of sunlight utilization. Notably, the fabricated Fe2O3/CuO-2 photoelectrode demonstrates a remarkable photocharging performance, far surpassing both Fe2O3 photoelectrodes and commercial TiO2 photoelectrodes. Specifically, the Fe2O3/CuO-2 photoelectrode boosts an average current density of 598.68 μA∙cm−2, with its charging current density being 2.74 and 5.15 larger, respectively, than that of the Fe2O3 and commercial TiO2 photoelectrodes.