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.
By introducing the composite structure of NRs heterojunction array, the interface areas of heterojunction and the channel of carrier separation were increased through the strategies of energy band matching, structure design and surface modification, thus improving the efficiency of carrier separation and collection.
This is more challenging to accomplish than the one- and two-electron reactions that produce lithium superoxide (LiO 2) and lithium peroxide (Li 2 O 2), respectively. A stable cathode with a sufficient supply of electrons and Li cations to form Li 2 O must be developed to achieve a four-electron reaction for a lithium–oxygen battery.
The preparation of the Fe 2 O 3 -CuO heterojunction photoelectrode is conducted in two consecutive steps: (1) Growth of Fe 2 O 3 on Fluorine-Doped Tin Oxide (FTO) via Hydrothermal Method: Initially, the FTO substrate is thoroughly cleaned with deionized water and absolute ethanol, followed by drying at 50 °C.
Therefore, by introducing the heterojunction array structure, the carrier separation channel is increased by the interface area of the heterojunction, thereby improving the carrier separation and collection efficiency.
The formation of this heterojunction structure aims at broadening the solar absorption spectrum of the independent Fe 2 O 3 photoelectrode, negatively shifting the flat band potential of the photoelectrode, reducing the recombination rate of photogenerated electrons/holes.