Effectively enhancing the performance of solar flow battery via constructing TiO₂-g-C₃N₄ heterojunction photoanode

This work presents the synthesis of titanium dioxide nanorods-graphitic carbon nitride (TiO₂-g-C₃N₄) and its application as a photoanode in solar flow batteries (SFBs). One-dimensional nanorod array TiO₂ films are fabricated on fluorine-doped tin oxide (FTO) conductive glass surfaces via hydrothermal method. The single-crystalline nanorods provide a direct pathway for photogenerated electrons, thus enhancing the electron transfer rate and improving the performance of the photovoltaic device. Subsequently, g-C₃N₄ is introduced onto the TiO₂ surface through microwave-heating techniques to construct a heterojunction. Incorporating g-C₃N₄ with a lower bandgap and constructing the heterojunction enhances the light absorption capability of photoelectrode while reducing carrier recombination, thereby boosting photocatalytic efficiency. Utilizing these materials as photoanodes, integrated solar flow batteries are fabricated. Full cell testing demonstrates that the photocurrent density of the heterojunction TiO₂-g-C₃N₄ photoanode reaches 600 μA cm⁻², which is four times higher compared with that of pure TiO₂ photoanode at 120 μA cm⁻². The work described here provides an effective approach to address the issues of low photoconversion efficiency and low performance for SFBs.