Hematite (Fe₂O₃) has been widely used as a photoanode in photoelectrochemical water splitting (PEC) for green hydrogen production. Here, for the first time, we investigate how a simple in-situ phosphorus (P) doping strategy improves the overall PEC performance of hematite with a systematic analysis of the various effects on the PEC performance. By introducing enriched FePO₄ regions on the Ti-doped FeOOH surface and subsequent high-temperature annealing via P-doping, meso-porous P,Ti co-doped Fe₂O₃ (P,Ti-Fe₂O₃) nanorods were fabricated. P,Ti-Fe₂O₃ exhibited four-fold and two-fold increased BET surface area and electrical active area, respectively, compared to that of Ti-Fe₂O₃. Benefiting from the nano-structuring and efficient P doping effects [e.g., increased carrier density (N_d=3.48168 ×10²⁰ cm⁻³), enhanced charge separation (η_bulk= 38.7% and η_surface= 79.1%), and steeper band bending (W_d=3.910 nm)], the resulting P,Ti-Fe₂O₃ photoanode exhibited 94% improved photocurrent density of 2.50 mA cm⁻² compared to that of Ti-Fe₂O₃ (@ 1.23 V_RHE) under 1 sun illumination. With the deposition of the NiFeO_x cocatalyst, the NiFeO_x/P,Ti-Fe₂O₃ photoanode exhibited excellent photocurrent density of 3.54 mA cm⁻² (@ 1.23 V_RHE) with a remarkable cathodic shift (180 mV) of the onset potential, marking the highest value among P doped hematite studies. This study suggests a new paradigm of P doped hematite with mesopores and gradient doping properties affordable in a cost-efficient way, achieving an excellent PEC water splitting performance.

赤铁矿 (Fe ₂ O ₃ ) 已被广泛用作光电化学水分解 (PEC) 中的光电阳极，用于绿色制氢。在这里，我们首次研究了简单的原位磷 (P) 掺杂策略如何通过系统分析对 PEC 性能的各种影响来提高赤铁矿的整体 PEC 性能。通过在 Ti 掺杂的 FeOOH 表面引入富集的 FePO ₄区域并随后通过 P 掺杂进行高温退火，制备了介孔 P,Ti 共掺杂 Fe ₂ O ₃ (P,Ti-Fe ₂ O ₃ ) 纳米棒. P,Ti-Fe ₂ O _{3与 Ti-Fe 2} O ₃相比，BET 表面积和电活性面积分别增加了四倍和两倍。受益于纳米结构和有效的 P 掺杂效应 [例如，增加的载流子密度（N _d =3.48168 ×10 ²⁰ cm ^-3），增强的电荷分离（η _bulk = 38.7% 和 η _surface = 79.1%），以及更陡的带弯曲 (W _{d =3.910} ^nm )]，所得 P,Ti-Fe ₂ O ₃光阳极与 Ti-Fe ₂ O ₃ (@ 1.23 V_RHE ) 在 1 个太阳光照下。随着 NiFeO _x助催化剂的沉积，NiFeO _x /P,Ti-Fe ₂ O ₃光阳极表现出 3.54 mA cm ^-2 (@ 1.23 V _RHE ) 的优异光电流密度，并具有显着的起始阴极位移 (180 mV)潜力，标志着 P 掺杂赤铁矿研究中的最高值。这项研究提出了一种新的 P 掺杂赤铁矿范例，该赤铁矿具有中孔和梯度掺杂特性，且成本低廉，可实现出色的 PEC 水分解性能。