Photocatalytic water oxidation suffers from sluggish kinetics and remains the bottleneck for water splitting. Here, using CeO₂ nanorods as model photocatalyst we studied the critical role of oxygen vacancies in photocatalytic water oxidation. First CeO₂ nanorods with similar morphology but different concentration of oxygen vacancies were fabricated by one-step hydrothermal method with in-situ reducing treatment. The optical absorption, charge transfer efficiency, and photocatalytic activity in oxygen generation were found closely dependent on the concentration of oxygen vacancies. Then density functional theory calculations were conducted to unveil the role of oxygen vacancies and understand the water oxidation mechanism. It was found the presence of oxygen vacancies narrows the bandgap and modulates the electronic structure for accelerating the charge transfer, in good agreement with the experimental observations. The overall oxygen generation pathway was screened and the oxygen vacancies were found to lower the barrier energy for the rate limiting step of OO bond formation and restrain the reverse reaction of O and H, thus the O₂ generation kinetics on oxygen-defective CeO₂ are improved significantly. This study provides in-depth understanding on the critical role of oxygen vacancies in photocatalytic water oxidation and is helpful for designing highly efficient photocatalyst to overcome the bottleneck of water splitting.

光催化水氧化反应动力学缓慢，并且仍然是水分解的瓶颈。在这里，我们使用CeO ₂纳米棒作为模型光催化剂，我们研究了氧空位在光催化水氧化中的关键作用。第一CeO ₂通过一步水热法原位还原法制备了形态相似但氧空位浓度不同的纳米棒。发现氧气产生中的光吸收，电荷转移效率和光催化活性与氧气空位的浓度密切相关。然后进行密度泛函理论计算以揭示氧空位的作用并了解水的氧化机理。发现氧空位的存在使能带隙变窄并且调节电子结构以加速电荷转移，这与实验观察非常吻合。筛选了整个氧气生成途径，发现氧空位降低了O限速步骤的势垒能O键的形成和抑制了O和H的逆反应，因此氧缺陷型CeO ₂上的O ₂生成动力学得到显着改善。这项研究提供了氧空位在光催化水氧化中的关键作用的深入了解，并有助于设计高效的光催化剂来克服水分解的瓶颈。