Introducing oxygen vacancies in transition-metal oxides is an effective method to improve electrocatalytic water oxidation activity. However, controlled defect engineering in metal oxides remains a challenge. In this study, high oxygen vacancy content is achieved in transition-metal oxides by regulating the pyrolysis temperature of corresponding metal hydroxides. Specifically, Co₃O₄ nanoflowers with a large amount of oxygen vacancies were obtained by pyrolysis of Co(OH)₂ in air at 400°C. The high oxygen vacancy content may be due to the rich porous structure and atomic rearrangement of Co and O. Electrochemical results showed that oxygen vacancy defect-rich Co₃O₄ prepared at 400°C (Co₃O₄-400) has the lowest overpotential η of 321 mV for oxygen evolution reaction at a current density j of 10 mA cm⁻² in 1.0 mol L⁻¹ KOH compared with Co₃O₄-300 (348 mV) and Co₃O₄-500 (366 mV). Theoretical calculations and experiments verified the beneficial effect of oxygen vacancies in Co₃O₄. This study offers an efficient strategy to develop highly active transition-metal oxides with optimized oxygen vacancies.

在过渡金属氧化物中引入氧空位是提高电催化水氧化活性的有效方法。然而，金属氧化物的受控缺陷工程仍然是一个挑战。在这项研究中，通过调节相应金属氢氧化物的热解温度，在过渡金属氧化物中实现了高氧空位含量。具体而言，通过Co(OH) ₂在空气中400℃热解得到具有大量氧空位的Co ₃ O _{4纳米花。}高氧空位含量可能是由于Co和O丰富的多孔结构和原子重排所致。电化学结果表明，400℃制备的富含氧空位缺陷的Co ₃ O _{4 (Co 3} O ₄ -400)具有最低的氧空位含量。与 Co ₃ O ₄ -300 (348 mV) 和 Co ₃ O ₄ -500 (366 mV)相比，在 1.0 mol L ^-1 KOH 中，在电流密度j 10 mA cm ^-2下，析氧反应的过电势η为 321 mV 。_{理论计算和实验验证了Co 3} O ₄中氧空位的有益作用。这项研究提供了一种开发具有优化氧空位的高活性过渡金属氧化物的有效策略。