The scope of any metal oxide as a catalyst for driving electrocatalytic reactions depends on its electronic structure, which is correlated to its oxygen‐defect density. Likewise, to transform a spinel oxide, such as cobalt ferrite (CoFe₂O₄), into a worthy universal‐pH, bifunctional electrocatalyst for the hydrogen and oxygen evolution reactions (HER and OER, respectively), oxygen defects need to be regulated. Prepared by coprecipitation and inert calcination at 650 °C, CoFe₂O₄ nanoparticles (NPs) require 253 and 300 mV OER overpotentials to reach current densities of 10 and 100 mA cm⁻², respectively, if nickel foam is used as a substrate. With cost‐effective carbon fiber paper, the OER overpotential increases to 372 mV at 10 mA cm⁻² at pH 14. The NPs prepared at 550 °C require HER overpotentials of 218, 245, and 314 mV at −10 mA cm⁻² in alkaline, acidic, and neutral pH, respectively. The intrinsic activity is reflected from turnover frequencies of >3 O₂ s⁻¹ and >5 H₂ s⁻¹ at overpotentials of 398 and 259 mV, respectively. If coupled for overall water splitting, the extremely durable two‐electrode electrolyzer requires a cell potential of only 1.63 V to reach 10 mA cm⁻² at pH 14. The homologous couple also splits seawater at impressively low cell voltages of 1.72 and 1.47 V at room temperature and 80 °C, respectively.

中文翻译：

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用于实际水电解的富氧缺陷钴铁氧体纳米颗粒，具有高活性和耐用性。

任何金属氧化物作为驱动电催化反应的催化剂的范围取决于其电子结构，而电子结构与其氧缺陷密度相关。同样，为了将钴铁氧体 (CoFe ₂ O ₄ ) 等尖晶石氧化物转化为有价值的通用 pH 值、用于析氢反应和析氧反应（分别为 HER 和 OER）的双功能电催化剂，需要调节氧缺陷。如果使用泡沫镍作为基材，通过共沉淀和 650 °C 惰性煅烧制备的 CoFe ₂ O ₄纳米粒子 (NPs) 需要 253 和 300 mV OER 过电势才能分别达到 10 和 100 mA cm ^{-2的电流密度。}使用具有成本效益的碳纤维纸，OER 过电势在 10 mA cm ^{-2、 pH 14 下增加至 372 mV。在 550 °C 下制备的纳米粒子需要 HER 过电势在 -10 mA cm -2}下为 218、245 和 314 mV分别在碱性、酸性和中性 pH 值下。内在活性反映在过电势分别为398和259 mV时>3 O ₂  s ^-1和>5 H ₂  s ^{-1的周转频率。}如果耦合用于整体水分解，极其耐用的双电极电解槽只需 1.63 V 的电池电位即可在 pH 14 下达到 10 mA cm ^-2。同源对还可以在 1.72 和 1.47 V 的极低电池电压下分解海水。分别为室温和 80°C。