Liquid-phase deposition of α-Fe2O3/n-Si heterojunction thin film photoanode for water splitting

The Liquid-phase deposition (LPD) method stands out as one of the most cost-effective techniques for fabricating thin films, due to its simple equipment requirements, low operational costs, and easy scalability while maintaining excellent film quality. In this work, we successfully demonstrate for the first time the synthesis of a heterojunction thin-film photoanode of hematite ($\alpha -{\mathrm{Fe}}_2{O}_3$) on an n-type silicon $\left(n-\mathrm{Si}\right)$ substrate using LPD. The $\alpha -{\mathrm{Fe}}_2{O}_3/n-\mathrm{Si}$ heterojunction photoanodes fabricated by LPD exhibited superior photocurrent responses for water splitting, with greater light absorption and enhanced performance compared to photoanodes prepared on fluorine-doped tin oxide (FTO) glass substrates, indicating the high quality of the heterojunction interface. The LPD-fabricated heterojunctions showed an early onset of photocurrent at lower applied potentials compared to Pt-based metal electrodes, demonstrating a reduction in overpotential voltage of 0.3 V. Overall, the LPD method shows promising potential for fabricating high-quality $\alpha -{\mathrm{Fe}}_2{O}_3/n-\mathrm{Si}$ thin films, with potential applications toward unassisted water splitting, offering an efficient and sustainable approach for green hydrogen production.