Search

Hydrogen energy is considered to be a zero-carbon chemical energy alternative to traditional fossil energy, and electrolysis of water, as one of the most effective methods of producing hydrogen, can produce high-purity hydrogen under the premise of zero pollution. The oxygen evolution reaction (OER) is a slow and energy-intensive four-electron process that limits the rate of decomposition of electrolyzed water and is considered as the bottleneck for overall water splitting. In this paper, CoNi2S4 nanosheets were assembled on blank nickel foam with a conventional two-step hydrothermal method, which then was continued with a hydrothermal method to load the diamond-block structure of MIL-53(Fe) on top of CoNi2S4 nanosheets, denoted as MIL-53(Fe)@CoNi2S4/NF. The MIL-53(Fe)@CoNi2S4/NF catalyst exhibited excellent electrochemical performance in 1 M KOH aqueous solution, which required an overpotential of only 201 mV when the current density reached 20 mA cm−2. In addition, after long-term stability testing, the MIL-53(Fe)@CoNi2S4/NF catalyst maintained its favourable OER activity due to the lattice structure of the rhombic blocks which enhanced both the stability of the catalyst structure and the internal ion transport channels. [ABSTRACT FROM AUTHOR]

In recent years, Co-based metal–organic frameworks (Co-MOFs) have received significant research interest because of their large specific surface area, high porosity, tunable structure and topological flexibility. However, their comparatively weak electrical conductivity and inferior stability drastically restrict the application of Co-MOFs in the synthesis of electrocatalysts. In this study, ZIF-67 was grown on nickel foam by a room temperature soaking method, and then Ir–Co(OH)2@ZIF-67/NF was assembled by a hydrothermal method. The prepared Ir–Co(OH)2@ZIF-67/NF nanosheets exhibit remarkable conductivity, larger electrochemical active surface area and wider electron transport channels. Only ultralow overpotentials of 198 mV, 263 mV, and 300 mV were needed for Ir–Co(OH)2@ZIF-67/NF to reach the current densities of 10 mA cm−2, 50 mA cm−2, 100 mA cm−2, meanwhile, no obvious degradation of the current density at 10 mA cm−2 was observed for about 16 h. This work may provide a promising strategy for developing high-performance MOF-derived materials as electrocatalysts for the OER under alkaline conditions. [ABSTRACT FROM AUTHOR]

Due to the slow reaction kinetics of the oxygen evolution reaction (OER), the electrolysis rate of water is greatly limited. Therefore, it is of great significance to study stable and efficient non-noble metal based electrocatalysts. In this paper, three-dimensional (3D) spherical V-NiFe LDH@Ni3S2 was developed by exquisitely decorating ultra-thin V-doped NiFe layered dihydroxide (NiFe-LDH) on Ni3S2 nanosheets supported by nickel foam (NF). It is worth mentioning that V-NiFe LDH@Ni3S2 exhibits an excellent electrocatalytic performance and only 178 mV overpotential is required in 1 M KOH to achieve a current density of 10 mA cm−2. Long-term chronoamperometry manifests its superior electrochemical stability. The combination of NiFe LDH and conductive substrate coupling can drastically afford abundant active sites and accelerate charge transfer, and V doping can markedly regulate the electronic structure. Therefore, the activity and durability of the electrocatalysts are greatly improved. This study may provide a new strategy for the preparation of efficient OER electrocatalysts. [ABSTRACT FROM AUTHOR]