Developing noble metal-free electrocatalysts (NMFEs) for the oxygen evolution reaction (OER) is tremendously challenging in acid. Despite extensive research efforts, few reported NMFEs can compete with Ru/Ir oxides for acidic OERs. Here, we report a heterostructure-engineering method to break the activity–stability limit of OER electrocatalysts and yield a noble-metal-free oxide that competes with RuO₂ in terms of OER specific activity and stability in acid. Via a set of correlative operando characterization techniques, heterostructured Co₃O₄/MnO₂ suppressed the in situ reconstruction of Co₃O₄ and MnO₂, and mitigated the electrochemical cycling-accelerated catalyst leaching, thus improving the acidic OER stability. Moreover, first-principles calculations supported that the synergy of Co and Mn in Co₃O₄/MnO₂ lowered the theoretical OER overpotentials. The optimized Co₃O₄/MnO₂ achieved an activity of 10 mA cm⁻² at 319 ± 1.2 mV overpotential, and it demonstrated low degradation during the varying-current stability test (up to 200 mA cm⁻²) for 100 hours, making it among the best NMFEs for acidic OERs. Moreover, the promising performance of Co₃O₄/MnO₂ as the anodic catalyst was also validated in a proton-conducting membrane water electrolysis cell.

中文翻译：

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异质结构增强了酸中不含贵金属的析氧电催化剂


开发用于酸析氧反应 (OER) 的不含贵金属的电催化剂 (NMFE) 极具挑战性。尽管进行了大量的研究工作，但很少有报道称 NMFE 可以与 Ru/Ir 氧化物竞争酸性 OER。在这里，我们报告了一种异质结构工程方法，以打破 OER 电催化剂的活性-稳定性极限，并产生一种不含贵金属的氧化物，在 OER 比活性和酸稳定性方面与 RuO ₂ 竞争。通过一系列相关的操作表征技术，异质结构Co ₃ O ₄ /MnO ₂ 抑制了Co ₃ O的原位重构 ₄ 和MnO ₂ ，并减轻了电化学循环加速催化剂的浸出，从而提高了酸性OER稳定性。此外，第一性原理计算支持 Co ₃ O ₄ /MnO ₂ 中 Co 和 Mn 的协同作用降低了理论 OER 超电势。优化后的 Co ₃ O ₄ /MnO ₂ 在 319 ± 1.2 mV 过电位下实现了 10 mA cm ⁻² 的活性，并且在 100 小时的变电流稳定性测试（高达 200 mA cm ⁻² ）中表现出较低的降解，使其成为酸性 OER 的最佳 NMFE 之一。此外，Co ₃ O ₄ /MnO ₂ 作为阳极催化剂的良好性能也在质子传导膜水电解槽中得到了验证。