Semisacrificial Template Growth of Self-Supporting MOF Nanocomposite Electrode for Efficient Electrocatalytic Water Oxidation

Herein, the authors report, for the first time, the semisacrificial template growth of a self-supporting metal-organic framework (MOF) nanocomposite electrode composed of ultrasmall iron-rich Fe(Ni)-MOF cluster-decorated ultrathin Ni-rich Ni(Fe)-MOF nanosheets from the NiFe alloy foam, in which the Fe(Ni)-MOF clusters are uniform with a particle size of 2-5 nm, while the thickness of the Ni(Fe)-MOF nanosheets is only about 1.56 nm. When directly used as a self-supported working electrode for the oxygen evolution reaction (OER), it can afford an impressive electrocatalytic performance with required overpotentials of 227 and 253 mV to achieve current densities of 10 and 100 mA cm(-2), respectively, much outperforming the benchmark of RuO2 and most state-of-the-art noble-metal-free catalysts. Characterizations demonstrated that the combination of the unique nanostructure of the catalyst and the strong coupling effect between Ni and Fe active sites should be responsible for its excellent OER performance. Remarkably, when coupled with a Pt electrode in an overall water splitting system, they only needed 1.537 V to achieve a current density of 10 mA cm(-2). The facile and economical methodology represents a new way to design and prepare high-performance self-supporting MOF electrocatalysts for highly efficient electrochemical processes.