Niu Hua-Jie, Ran Nian, Zhou Wei, An Weixuan, Huang Chuanxue, Chen Wenxing, Zhou Min, Lin Wen-Feng, Liu Jianjun, Guo Lin
School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology, Beihang University, Beijing 100191, China.
State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.
J Am Chem Soc. 2025 Jan 22;147(3):2607-2615. doi: 10.1021/jacs.4c14675. Epub 2025 Jan 8.
The dual-site synergistic catalytic mechanism on NiFeOOH suggests weak adsorption of Ni sites and strong adsorption of Fe sites limited its activity toward alkaline oxygen evolution reaction (OER). Large-scale density functional theory (DFT) calculations confirm that Co doping can increase Ni adsorption, while the metal vacancy can reduce Fe adsorption. The combined two factors can further modulate the atomic environment and optimize the free energy toward oxygen-containing intermediates, thus enhancing the OER activity. Accordingly, we used Co doping and Cr vacancies to fabricate an amorphous catalyst of ,Co-NiFeOOH. It provides an OER overpotential of 239 mV at 100 mA cm and high stability over 500 h at 500 mA cm with a ∼98% potential retention. The resulting water electrolyzer based on an anion exchange membrane (AEM) exhibits a remarkable performance of 1 A cm at 1.68 V in 1 M KOH. XPS, soft-XAS, and XANES combined with Bader charge analysis results reveal that the regulation of the local microenvironment can increase the valence state of Ni by Co doping, thus improving the adsorption energy on Ni sites. The Cr vacancy can alleviate the strong adsorption on Fe sites. DFT calculations confirm that the synergistic effect of Co doping and Cr vacancies can redistribute the charge on the Ni/Fe sites, optimize the d-band center of Ni and Fe, and endow the catalyst with Ni-Fe dual sites to reduce the energy barrier of the OER rate-determining step.
NiFeOOH上的双位点协同催化机制表明，Ni位点的弱吸附和Fe位点的强吸附限制了其对碱性析氧反应（OER）的活性。大规模密度泛函理论（DFT）计算证实，Co掺杂可以增加Ni的吸附，而金属空位可以减少Fe的吸附。这两个因素的结合可以进一步调节原子环境并优化含氧中间体的自由能，从而提高OER活性。因此，我们使用Co掺杂和Cr空位制备了一种非晶态催化剂，即Co-NiFeOOH。它在100 mA cm下提供239 mV的OER过电位，在500 mA cm下500 h内具有高稳定性，电位保留率约为98%。基于阴离子交换膜（AEM）的所得水电解槽在1 M KOH中于1.68 V下表现出1 A cm的优异性能。XPS、软X射线吸收光谱（soft-XAS）和X射线吸收近边结构（XANES）结合巴德电荷分析结果表明，局部微环境的调节可以通过Co掺杂提高Ni的价态，从而提高在Ni位点上的吸附能。Cr空位可以减轻在Fe位点上的强吸附。DFT计算证实，Co掺杂和Cr空位的协同效应可以重新分布Ni/Fe位点上的电荷，优化Ni和Fe的d带中心，并赋予催化剂Ni-Fe双位点以降低OER速率决定步骤的能垒。
