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

Abstract

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.

Recent Approaches to Design Electrocatalysts Based on Metal–Organic Frameworks and Their Derivatives

“…For instance, fabrication of MOFs as ultrathin nanosheets or thin film can provide the opportunities to achieve high density of the exposed active sites . On the other hand, utilization of nanostructured/porous supports and downsizing/shaping the electrocatalysts would also be a promising way to increase the number of exposed active sites. For example, Li and co‐workers reported an example of preparing Co‐based nanoparticles embedded in hollow N‐doped carbon polyhedra for boosing the ORR/OER from pyrolysis‐oxidation with Co‐based MOF precursor .…”

Hierarchical Hollow Co/N-C@NiCo2O4 Microsphere as an Efficient Bi-functional Electrocatalyst for Rechargeable Zn–Air Battery

“…XPS measurement of H-Co/N-C@NiCo 2 O 4 after all electrochemical tests exhibits some predictable changes (Figure S13). Namely, the valence state of Co and Ni has increased after all electrochemical tests, which is an unavoidable result after working at a high potential (Cao et al, 2018;Gu et al, 2018).…”

Bimetal−Organic Framework Derived High‐Valence‐State Cu‐Doped Co3O4 Porous Nanosheet Arrays for Efficient Oxygen Evolution and Water Splitting

“…Electrochemical water splitting provides a facile and green method for scalable hydrogen energy supply, which plays a significant role in circumventing the dilemma of prominent energy crisis and environmental issues derived from the excessive consumption of fossil fuels. [1][2][3][4][5][6][7] However, the widespread commercial applications of overall water splitting are still being impeded by the intrinsically sluggish kinetics of oxygen evolution reactions (OER), which requires high-active electrocatalyst to overcome the large activation potentials. [8][9][10][11][12][13][14] At present, noble metal-based oxides of ruthenium (RuO 2 ) and iridium (IrO 2 ) are regarded as the most efficient OER electrocatalysts.…”