【摘要】 析氧反应（OER）是阴离子交换膜电解水制氢（AEMWE）的关键阳极过程,但其缓慢的四电子转移动力学以及对贵金属催化剂的依赖,严重限制了绿氢技术的规模化发展.因此,开发高效、稳定的非贵金属OER催化剂至关重要.高熵氧化物（HEO）凭借多元素协同效应、可调的电子结构、高熵效应及晶格畸变等优势,在OER催化中展现出媲美甚至超越贵金属催化剂的活性.然而,目前HEO的制备仍面临均相合成困难的问题,尤其是传统高温固相法能耗高、反应时间长,且易导致颗粒烧结和粗化.因此,发展小粒径非贵金属HEO的可控制备方法具有重要意义.基于上述问题,本研究创新采用单靶材磁控溅射技术,在泡沫镍基底上原位构筑了均相尖晶石型非贵金属HEO薄膜催化剂,其由大量平均粒径仅为2.5 nm的（FeCoNiCrMo）₃O₄超细晶粒组成,有效解决了传统高温固相法制备HEO过程中存在的颗粒烧结和相分离等难题.所制备的（FeCoNiCrMo）₃O₄HEO薄膜催化剂展现出优异的OER性能:在1.0 mol L^-1 KOH中,10 mA cm^-2电流密度下OER过电位为216 mV, Tafel斜率仅为41.16 mV dec^-1,且在100 mA cm^-2电流密度下稳定运行200 h的活性衰减率仅为272 μV h^-1,各项OER性能指标均显著优于商业IrO₂催化剂(290 mV, 74.92 mV dec^-1, 1090 μV h^-1).机理研究发现, pH依赖性实验证明了（FeCoNiCrMo）₃O₄HEO薄膜催化剂遵循质子耦合电子转移机制;四甲基铵阳离子探针实验表明,该HEO薄膜催化剂的OER过程遵循吸附质演化机制;通过拟合催化剂在不同温度下的线性扫描伏安曲线绘制出的Arrhenius图,证实HEO薄膜催化剂较IrO₂具有更低的活化能,表明其OER动力学更快.甲醇分子探针实验表明, Mo元素的引入有效降低了催化剂表面含氧中间体^*OH的吸附强度,进而促进后续脱质子化过程,提高了OER速率.密度泛函理论计算表明,（FeCoNiCrMo）₃O₄与（FeCoNiCr）₃O₄两种材料的决速步骤均在^*O的形成阶段,其中（FeCoNiCr）₃O₄的RDS能垒为2.10 eV,明显高于（FeCoNiCrMo）₃O₄ （1.83 eV）,这从理论上解释了Mo的引入对催化剂OER活性的提升机制,与电化学性能的测试结果以及表观活化能的分析结论相一致.综上所述,本文不仅建立了超细HEO薄膜催化剂的可控制备新方法,更通过电化学实验与理论计算的有机结合,为设计高效非贵金属析氧反应催化剂提供了新策略,对推动电解水制氢技术的实际应用具有重要价值.更多还原

【Abstract】 Ensuring high electrocatalytic performance simultaneously with low or even no precious-metal usage is still a big challenge for the development of electrocatalysts toward oxygen evolution reaction（OER） in anion exchange membrane water electrolysis. Here, homogeneous high entropy oxide（HEO） film is in-situ fabricated on nickel foam（NF） substrate via magnetron sputtering technology without annealing process in air, which is composed of many spinel-structured（FeCoNiCrMo）₃O₄ grains with an average particle size of 2.5 nm. The resulting HEO film（abbreviated as（FeCoNiCrMo）₃O₄） exhibits a superior OER performance with a low OER overpotential of 216 mV at 10 mA cm^-2 and steadily operates at 100 mA cm^-2 for 200 h with a decay of only 272 μV h^-1, which is far better than that of commercial IrO₂ catalyst(290 mV, 1090 μV h^-1). Tetramethylammonium cation（TMA⁺） probe experiment, activation energy analysis and theoretical calculations unveil that the OER on（FeCoNiCrMo）₃O₄ follows an adsorbate evolution mechanism pathway, where the energy barrier of rate-determining step for OER on（FeCoNiCrMo）₃O₄ is substantially lowered. Also, methanol molecular probe experiment suggests that a weakened ^*OH bonding on the（FeCoNiCrMo）₃O₄ surface and a rapid deprotonation of ^*OH, further enhancing its OER performance. This work provides a feasible solution for designing efficient high entropy oxides electrocatalysts for OER, accelerating the practical process of water electrolysis for H₂ production.更多还原