Ni Yuanman, Shi Dier, Mao Baoguang, Wang Sihong, Wang Yin, Ahmad Ashfaq, Sun Junliang, Song Fang, Cao Minhua, Hu Changwen
Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China.
State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China.
Small. 2023 Nov;19(45):e2302556. doi: 10.1002/smll.202302556. Epub 2023 Jul 19.
Hierarchically structured bimetal hydroxides are promising for electrocatalytic oxygen evolution reaction (OER), yet synthetically challenging. Here, the nanoconfined hydrolysis of a hitherto unknown CoFe-bimetal-organic compound (b-MOC) is reported for the controllable synthesis of highly OER active nanostructures of CoFe layered double hydroxide (LDH). The nanoporous structures trigger the nanoconfined hydrolysis in the sacrificial b-MOC template, producing CoFe LDH core-shell octahedrons, nanoporous octahedrons, and hollow nanocages with abundant under-coordinated metal sites. The hollow nanocages of CoFe LDH demonstrate a remarkable turnover frequency (TOF) of 0.0505 s for OER catalysis at an overpotential of 300 mV. It is durable in up to 50 h of electrolysis at step current densities of 10-100 mA cm . Ex situ and in situ X-ray absorption spectroscopic analysis combined with theoretical calculations suggests that under-coordinated Co cations can bind with deprotonated Fe-OH motifs to form OER active Fe-O-Co dimmers in the electrochemical oxidation process, thereby contributing to the good catalytic activity. This work presents an efficient strategy for the synthesis of highly under-coordinated bimetal hydroxide nanostructures. The mechanistic understanding underscores the power of maximizing the amount of bimetal-dimer sites for efficient OER catalysis.
具有分层结构的双金属氢氧化物在电催化析氧反应（OER）方面具有潜力，但合成具有挑战性。在此，报道了一种迄今未知的钴铁双金属有机化合物（b-MOC）的纳米限域水解，用于可控合成具有高OER活性的钴铁层状双氢氧化物（LDH）纳米结构。纳米多孔结构触发了牺牲性b-MOC模板中的纳米限域水解，生成了具有丰富低配位金属位点的钴铁LDH核壳八面体、纳米多孔八面体和中空纳米笼。钴铁LDH的中空纳米笼在300 mV过电位下对OER催化表现出0.0505 s的显著周转频率（TOF）。在10 - 100 mA cm的阶跃电流密度下进行长达50 h的电解时，它具有耐久性。非原位和原位X射线吸收光谱分析结合理论计算表明，低配位的钴阳离子在电化学氧化过程中可与去质子化的Fe-OH基序结合形成OER活性的Fe-O-Co二聚体，从而有助于良好的催化活性。这项工作提出了一种合成高度低配位双金属氢氧化物纳米结构的有效策略。机理理解强调了最大化双金属二聚体位点数量以实现高效OER催化的作用。
