电解水技术是制取高纯度氢气的有效途径,为传统的氢气生产提供了一种可持续的替代方案.其中,开发性能优异的电催化材料是降低电解水制氢成本的关键.析氧反应(OER)由于涉及多个电子转移而导致的动力学缓慢,是克服高过电位的主要挑战.镍铁羟基/氢氧化物(NiFe(oxy)hydroxides)是近期研究的热点,其在碱性条件下具有极低的OER过电位,部分材料性能甚至超过了贵金属基催化剂,如IrO2和RuO2.然而,NiFe(oxy)hydroxides的长期催化稳定性,尤其是在大电流下的长期催化稳定性,成为限制其实际应用的主要问题,这主要是由于铁元素的严重流失导致的.因此,如何有效控制和利用电化学溶解/沉积动力学成为稳定铁位点的关键.为克服该挑战,本文提出了一种大电流极化重构方法来固定活性铁位点.通过在大电流(1.5 A cm-2)下对材料进行表面快速极化重构,成功制备了FeOOH@NiOOH(eFNOL)电催化剂.eFNOL不仅具有稳定的铁位点,还暴露出高指数晶面,因此eFNOL同时展现出较好的OER催化活性和稳定性.同时,密度泛函理论计算结果表明,与具有低指数晶面的FeNiOOH相比,大电流极化工程制备的分相eFNOL对铁位点表现出更高的结合能,可以有效抑制OER过程中的铁流失,且高指数晶面在改变速率决定步骤和减少吸附能垒上具有更大的优势.电化学测试结果表明,经过优化后的eFNOL催化剂在产生100和500 mA cm-2大电流密度仅需234和27 mV的过电位,并且具有较小的Tafel斜率(35.2 mV dec-1).由于铁位点结合能的提高,eFNOL催化剂在500 mA cm-2的电流密度下能够稳定催化超过100 h,且仅有1.5％的性能衰减,优于近期报道的大多数镍铁基OER催化剂.综上,本文为开发高活性和高稳定性能的催化剂提供了一种有效的大电流电化学重构策略,在电解水制氢领域实现其工业化的大规模应用方面显示出巨大潜力,有望降低可持续电解水制氢成本.
Large-current polarization-engineered FeOOH@NiOOH electrocatalyst with stable Fe sites for large-current oxygen evolution reaction
NiFe-based (oxy)hydroxides are among the most efficient electrocatalysts for the oxygen evolution reaction (OER).However,significant Fe leakage during the OER results in unsatisfactory stability.Herein,a large-current (1.5 A cm-2) galvanostatic reconstruction was used to fabricate FeOOH@NiOOH (eFNOL) with both fixed Fe sites and exposed high-index crystal facets (HIFs).Compared to FeNiOOH with low-index crystal facets,the phase-separated FeOOH@NiOOH showed a higher binding energy towards Fe,and the HIFs significantly improved the catalytic activity of FeOOH.The optimized eFNOL catalyst exhibits ultralow overpotentials of 234 and 272 mV,yielding substantial current densities of 100 and 500 mA cm-2,respectively,with a small Tafel slope of 35.2 mV dec-1.Moreover,due to the stabilized Fe sites,its striking stability over 100 h at 500 mA cm-2 with 1.5％ decay outperforms most NiFe-based OER catalysts reported recently.This study pro-vides an effective strategy for developing highly active and stable catalysts via large-current elec-trochemical reconstruction.
Oxygen evolution reactionFeOOH@NiOOHLarge-current electrochemical reconstructionHigh-index crystal facetAnchor of Fe site
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维普
