In Situ Growth of Tetrametallic FeCoMnNi-MOF-74 on Nickel Foam as Efficient Bifunctional Electrocatalysts for the Evolution Reaction of Oxygen and Hydrogen

Abstract

Multivariate metal−organic frameworks (MTV-MOFs) have drawn much attention in recent years for their promising applications in many fields of chemistry and materials. Constructing functional MOFs from multiple components for electrochemical water is crucial to high performance renewable energy storage and conversion devices. In this work, a series of bitmetallic-, trimetallic-, and tetrametallic-MOF-74/NFs were grown in situ on nickel foam (NF) by a facile solvothermal route. Specifically, the optimized FeCoMnNi-MOF-74/NF with a multilevel and hollow nanostructure was successfully fabricated and used as highly efficient bifunctional electrocatalysts for water splitting. It exhibited an ultralow overpotential of 250 and 108 mV to achieve the current density of 50 and 10 mA cm −2 , along with the relatively small Tafel slope of 41.28 and 72.89 mV dec −1 for OER and HER in 1 M KOH, respectively. It is superior to other multimetallic-MOF-74 composites at the same condition and also surpasses the benchmark of commercial noble-metal catalysts as well. As a result, a low cell voltage of ca. 1.62 V was obtained at a current density of 10 mA cm −2 , when tetrametallic FeCoMnNi-MOF-74/NF is employed as both anode and cathode electrodes for the real water splitting. The present work potentially provides a new insight into prospecting and designing multivariate MOFs as a promising material for efficient electrocatalysis in the practical application.

Realizing electrochemical transformation of a metal–organic framework precatalyst into a metal hydroxide–oxy(hydroxide) active catalyst during alkaline water oxidation

“…15e and f). 72 The structural evolution of the MOF into ultrathin M(OH) 2 -M(O) x (OH) y nanosheets was also conrmed for NiFc-MOF and Co-MOF-Co(OH) 2 by PXRD studies. 76,111 The electrochemical transformation of PBA into ultrathin M(OH) 2 -M(O) x (OH) y nanosheets can also be determined by IR spectroscopic studies.…”

“…1). [67][68][69][70][71][72][73][74] In these cases, the MOF plays the role of a precatalyst and undergoes a series of structural reconstruction and selfassembly processes during the OER to form ultrathin M(OH) 2 -M(O) x (OH) y nanosheets. 36,56,58,[61][62][63]69,[75][76][77][78] MOFs have several advantages as a precatalyst like (i) the synthesis of MOFs is easy, facile, and scalable, (ii) the structural and electronic properties of MOFs can be easily tuned, (iii) MOFs undergo bulk and complete electrochemical transformation to form ultrathin M(OH) 2 -M(O) x (OH) y nanosheets and (iv) the required time for the electrochemical transformation is surprisingly low (few seconds to minutes).…”

Nanoporous ultra-high-entropy alloys containing fourteen elements for water splitting electrocatalysis

“… 1–3 The distinct components in multimetallic compounds can facilitate the adsorption/desorption of various ions or regulate charge transfer, thus promoting the overall reaction. 4 In addition, multimetallic compounds are amenable to structure optimization, crucial for maximizing the exposure of active sites and improving long-term stability. 5,6 High-entropy alloys (HEAs), first reported in 2004, are solid solutions composed of at least five metallic elements with atomic concentrations ranging from 5% to 35%.…”

Metal–Organic Frameworks‐Derived Self‐Supported Carbon‐Based Composites for Electrocatalytic Water Splitting

“…As a family of crystalline porous materials, the newly emerging MOFs prepared by connecting metal ions and organic ligands have attracted tremendous interests these years [68,69] . Owing to the high porosity, structural flexibility, and controllable functionality, lots of MOFs have been investigated as electrocatalysts for water electrolysis [24,70–83] . Moreover, MOFs can be in situ grown on conductive substrates through simple synthetic methods like hydro/solvothermal, electrodeposition, etc [84–89] .…”

“…[68,69] Owing to the high porosity, structural flexibility, and controllable functionality, lots of MOFs have been investigated as electrocatalysts for water electrolysis. [24,[70][71][72][73][74][75][76][77][78][79][80][81][82][83] Moreover, MOFs can be in situ grown on conductive substrates through simple synthetic methods like hydro/solvothermal, electrodeposition, etc. [84][85][86][87][88][89] Self-supported MOFs have been extensively employed as the rational precursors for the preparation of conductive substrate-integrated carbon-based composites with tunable morphologies and compositions by pyrolysis in the inert gas atmosphere.…”