The deficiencies in the separating photogenerated electrons/holes in the bulk and driving them across the interface of semiconductor/electrolyte are the major issues that limit the photoelectrochemical (PEC) performance of hematite (α-Fe₂O₃) photoelectrodes. In this work, a Z-scheme planar heterostructure of n-Si and α-Fe₂O₃ was designed and constructed by a facial ion-beam assisted deposition technique with the best match of the optical absorption depth, the film thickness and the space charge region thickness. A thin ITO layer (~10 nm) was sandwiched in-between in order to achieve the optimal carrier separation capacity, and the IrO_x cocatalysts were introduced to improve the surface reaction kinetics. The results demonstrate a significant improvement of α-Fe₂O₃ PEC performance: a photocurrent density was improved to 1.987 mA cm⁻² (1.23 V vs. RHE), ~100 times larger than that of bare α-Fe₂O₃, whereas the onset potential was dropped by 0.57 V over unmodified α-Fe₂O₃, due to the enhanced photovoltage by n-Si and the improved surface reaction kinetics. This work advances planar α-Fe₂O₃-based photocatalytic cells to a new performance record for water splitting.

分离主体中的光生电子/空穴并使其穿过半导体/电解质界面的缺陷是限制赤铁矿（α -Fe ₂ O ₃）光电极的光电化学（PEC）性能的主要问题。在这项工作中，通过面离子束辅助沉积技术设计和构造了n -Si和α -Fe ₂ O ₃的Z方案平面异质结构，其光吸收深度，膜厚度和空间的最佳匹配电荷区厚度。为了获得最佳的载流子分离能力，将ITO薄层（〜10 nm）夹在中间，并将IrO _x引入助催化剂以改善表面反应动力学。结果表明，α -Fe ₂ O ₃ PEC性能有了显着改善：光电流密度提高到1.987 mA cm ^-2（1.23 V vs. RHE），比裸α -Fe ₂ O ₃的光电流密度大100倍，而由于未改性的α -Fe ₂ O ₃引发的电势下降了0.57 V ，这是由于n -Si增强了光电压并改善了表面反应动力学。这项工作推进了平面α -Fe ₂ O ₃的光催化电池达到了新的水分解性能记录。