Developing highly efficient catalysts for oxygen evolution reactions (OER) is a key step for rechargeable metal–oxygen batteries and water splitting. Usually, binary NiFe or ternary NiCoFe nano-alloys are used as the OER catalysts. Herein, combining the precursor alloy design with chemical etching, a simple dealloying route is developed to controllably incorporate five or more nonprecious metals into one nanostructured alloy with a naturally oxidized surface, that is, nanoporous high entropy alloys (np-HEAs) covered with high-entropy (oxy)hydroxides (HEOs). It is found that the alloy composition plays a dominant role in the OER activity enhancement with the np-AlNiCoFeX (X = Mo, Nb, Cr) combination showing the highest activity. Forming quinary HEAs also greatly enhances the electrochemical cycling stabilities compared with the ternary and quaternary counterparts. The result indicates the significance of synergistically incorporating five or more metal elements in one single-phase nanostructure, which provides more structural and chemical degrees of freedom to boost the catalytic performance, overcoming the restriction of normal binary or ternary alloys. Multinary transition metal-based np-HEA is a new class of promising catalyst for various important reactions.

中文翻译：

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不含贵金属的纳米多孔高熵合金，用于氧释放反应的高效电催化剂

开发用于氧气逸出反应（OER）的高效催化剂是可充电金属氧气电池和水分解的关键步骤。通常，将二元NiFe或三元NiCoFe纳米合金用作OER催化剂。在此，将前体合金设计与化学蚀刻相结合，开发了一种简单的脱合金工艺，可控制地将五种或更多种非贵金属掺入一种具有自然氧化表面的纳米结构合金中，即，纳米多孔高熵合金（np-HEA）覆盖了高-熵（羟基）氧化物（HEOs）。发现合金成分在OER活性增强中起主要作用，其中np-AlNiCoFeX（X = Mo，Nb，Cr）组合表现出最高的活性。与三元和四元对应物相比，形成五元HEA还可以大大提高电化学循环稳定性。该结果表明了在一个单相纳米结构中协同掺入五种或更多金属元素的重要性，这提供了更多的结构和化学自由度以提高催化性能，克服了普通二元或三元合金的局限性。基于多元过渡金属的np-HEA是一类有前景的新型催化剂，可用于各种重要反应。