This work demonstrates the in-depth mechanism of enhanced photoelectrochemical (PEC) water oxidation of Sb-doped rutile TiO₂ nanorods (NRs) photoanode coupled with oxygen vacancy defect-rich Co-doped CeO_x (Co-CeO_x) oxygen evolution reaction (OER) cocatalyst. The defect-rich Co-CeO_x cocatalyst modification improves the conductivity, light absorption, charge transfer efficiency, and surface photovoltage generation of the Co-CeO_x/Sb-TiO₂ hybrid NRs photoanode. The Co-CeO_x cocatalyst also serves as the surface passivating overlayer for the Sb-TiO₂ photoanode, which suppresses the surface states mediated recombination of electron-hole pairs in the NRs. The PEC studies further indicate that Co-CeO_x cocatalyst induces remarkably large band bending at the semiconductor/electrolyte interface and shortens the carrier diffusion length and depletion layer width, facilitating the rapid separation and transportation of the photocarriers for the surface PEC reactions. The experimental and theoretical studies confirm that the Co-doping in CeO_x cocatalyst enhances the surface oxygen vacancy defects, which provides active catalytic sites for OH⁻ adsorption and charge transportation for enhanced OER kinetics. The density functional theory (DFT) calculations demonstrate a higher conductivity of the Co-CeO_x cocatalyst, advantageous for rapid charge transfer capability during PEC reactions. The synergy between all these merits helps the optimized Co-CeO_x/Sb-TiO₂ photoanode to deliver a maximum photocurrent density of 1.41 mA cm⁻² at 1.23 V vs. reversible hydrogen electrode (V_RHE) and an ultra-low turn on potential (V_on) of 0.1 V_RHE under AM 1.5G solar illumination compared to the Sb-TiO₂ NRs (0.96 mA cm⁻² at 1.23 V_RHE and V_on = 0.42 V_RHE). This work demonstrates the design of an efficient defect-rich cocatalyst modified photoanode for solar energy harvesting.

这项工作深入揭示了 Sb 掺杂的金红石 TiO ₂纳米棒 (NRs) 光阳极的增强光电化学 (PEC) 水氧化与富含氧空位缺陷的 Co 掺杂 CeO _x (Co-CeO _x ) 析氧反应的机理。 OER) 助催化剂。富含缺陷的 Co-CeO _x助催化剂改性提高了 Co-CeO _x /Sb-TiO ₂杂化 NRs 光阳极的电导率、光吸收、电荷转移效率和表面光电压产生。Co-CeO _x助催化剂还用作 Sb-TiO _{2的表面钝化覆盖层}光阳极，它抑制表面态介导的 NR 中电子 - 空穴对的重组。PEC 研究进一步表明，Co-CeO _x助催化剂在半导体/电解质界面引起显着大的能带弯曲，缩短载流子扩散长度和耗尽层宽度，促进表面 PEC 反应的光载流子的快速分离和传输。实验和理论研究证实，CeO _{x助催化剂中的共掺杂增强了表面氧空位缺陷，这为 OH} ^-吸附和电荷传输提供了活性催化位点，从而增强了 OER 动力学。密度泛函理论 (DFT) 计算表明 Co-CeO 的电导率更高_x助催化剂，有利于 PEC 反应期间的快速电荷转移能力。所有这些优点之间的协同作用有助于优化的 Co-CeO _x /Sb-TiO ₂光阳极在 1.23 V 相对于可逆氢电极 (V _RHE )提供 1.41 mA cm ^-2的最大光电流密度和超低开启与 Sb-TiO ₂ NRs (0.96 mA cm ^-2 at 1.23 V _RHE和 V _on  = 0.42 V _{RHE )}相比，AM 1.5G 太阳光照下的电位 ( V _on ) 为 0.1 V）。这项工作展示了一种用于太阳能收集的高效、富含缺陷的助催化剂改性光阳极的设计。