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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]

To overcome the problem of the sluggish kinetics of the oxygen evolution reaction (OER), it is of great significance to develop an efficient and stable non-noble metal-based OER catalyst for electrocatalytic energy conversion and storage. Herein, a complex of a metal–organic framework and hydroxide is synthesized by performing a ligand etching strategy on FeMn co-doped Ni(OH)2 nanosheets in situ grown on nickel foam (FeMn-Ni(OH)2@MOF/NF). Benefiting from the unique sheet-on-sheet hierarchical structure, multi-metal active nodes and two active materials grown in situ, the resulting FeMn-Ni(OH)2@MOF/NF demonstrated brilliant OER activity with an overpotential of 199 mV to achieve a current density of 10 mA cm−2 and long-term stability. This research will provide a new strategy for the design of high-performance OER electrocatalysts. [ABSTRACT FROM AUTHOR]

Since the complicated multiple electron transfer process and slow kinetics in the OER process seriously hinder the electrochemical decomposition of water, it is urgent to design and develop electrocatalysts with excellent performance and superior stability to reduce overpotential and accelerate the reaction dynamics of the OER. Herein, a unique ultra-thin nanosheet bimetal electrocatalyst NiFe-MOF/IF was synthesized by a one-step hydrothermal method, and characterized by SEM, XRD, TEM, and XPS. NiFe-MOF/IF shows superior OER electrocatalytic activity in 1 M KOH electrolyte solution, and an ultralow overpotential of only 230 and 262 mV was required to achieve a current density of 10 and 100 mA cm−2, respectively, with a relatively small Tafel slope of 30.46 mV dec−1 for the OER. No obvious degradation of the current density at 10 mA cm−2 was observed over about 16 h, which indicates the excellent stability of the catalyst. Favourable activity and benign durability of NiFe-MOF/IF can be attributed to the three-dimensional high porosity conductive substrates, in situ growth of MOF nanosheets, bimetallic synergy, and unique layering. This research provides a promising strategy for the application of MOF materials in the field of electrocatalysis. [ABSTRACT FROM AUTHOR]

The development of hydrogen evolution reaction (HER) electrocatalysts with outstanding efficiency and favorable stability at all pH values is of great significance but still a dominating challenge toward the development of electrochemical water-splitting technology. Herein, CoRu alloy nanoparticles assembled in Co4N porous nanosheets (named as CoRu@Co4N) have been successfully achieved from Ru(OH)3@Co(OH)2 through a one-step nitridation process. Benefiting from the unique structure, inherent alloy properties and strong alloy-support interaction derived from the in situ transformation, the resultant hybrids exhibit superior HER activities over a wide pH range, achieving very low overpotentials of 13 mV, 44 mV and 15 mV at 10 mA cm−2 under alkaline, neutral and acidic conditions, respectively. Such activities surpass most reported electrocatalysts and are comparable or even transcendent to commercial Ru/C and Pt/C. Furthermore, CoRu@Co4N also exhibits outstanding stability during the accelerated degradation test (ADT) and chronopotentiometry. Our work provides a new approach for designing pH-universal Ru-involved HER electrocatalysts with remarkable efficiency and prominent durability. [ABSTRACT FROM AUTHOR]

It is highly desirable for porous coordination polymers (PCPs), including metal–organic frameworks (MOFs) and Prussian blue analogues (PBAs), to retain their intrinsic characteristics in electrocatalysis, instead of being used as precursors or templates for further total conversion to other compounds via high-temperature calcination. Here, a S-treated two-dimensional (2D) CoFe bimetallic PBA grown on carbon fiber paper (CFP) (named S-CoFe-PBA/CFP) is assembled and applied as a highly efficient oxygen evolution reaction (OER) electrocatalyst in 1 M KOH. The resultant S-CoFe-PBA/CFP demonstrates significantly improved OER catalytic activity; overpotentials of only 235, 259, and 272 mV are needed to drive current densities of 10, 50, and 100 mA cm−2, respectively, with a super low Tafel slope of 35.2 mV dec−1. Even more noteworthy, a current density of 90 mA cm−2 can be achieved when a potential of 1.5 V vs. RHE is applied, which is 6.4 times higher than that of commercial Ir/C in the same environment. The outstanding electrocatalytic performance can be ascribed to two reasons caused by the S-treatment process. On one hand, H+ from intermediates of *OH and *OOH can be captured by –SOx distributed on the surface of the catalyst, thus accelerating the breaking of O–H; on the other hand, partial phase transformation of CoFe-PBA leads to the in situ formation of amorphous CoSx nanogauze on the surface, and the resultant electronic interactions between the two phases contribute much to the improvement of charge transfer and adsorption for OER intermediates. This work provides a new avenue for the design of highly efficient PCP-based OER electrocatalysts. [ABSTRACT FROM AUTHOR]

Cobaltite systems with spinel-type structures and Ni-based sulfides are deemed to be practical and promising water oxidation electrocatalysts because of their low cost, intrinsically admirable electroconductivity and predominant durability. However, most electrocatalysts still suffer from the challenge of an increase in the loading of active materials without sacrificing the geometry area. In this work, a CoFe2O4@Ni3S2/NF composite was achieved through a series of hydrothermal and annealing processes by means of constructing a vertically stacked bilayer heterostructure CoFe2O4@Ni3S2 on a 3D porous nickel foam (NF). The structure and morphology of the as-synthesized catalyst have been characterized by powder X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) analysis. The as-obtained CoFe2O4@Ni3S2/NF electrode, which possesses a vertically stacked bilayer nanosheet heterostructure, displays an improved OER performance and cyclic stability and shows an early onset potential with a low overpotential (231 mV at 10 mA cm−2) in a 1.0 M KOH solution. In addition, CoFe2O4@Ni3S2/NF demonstrates dependable durability and delivers outstanding current density of ∼15 mA cm−2 without activity degradation for 20 h. This approach provides a new insight into developing earth-abundant, low-cost and high-efficiency OER electrocatalysts. [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@Ni 3 S 2 was developed by exquisitely decorating ultra-thin V-doped NiFe layered dihydroxide (NiFe-LDH) on Ni 3 S 2 nanosheets supported by nickel foam (NF). It is worth mentioning that V-NiFe LDH@Ni 3 S 2 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.

To overcome the problem of the sluggish kinetics of the oxygen evolution reaction (OER), it is of great significance to develop an efficient and stable non-noble metal-based OER catalyst for electrocatalytic energy conversion and storage. Herein, a complex of a metal-organic framework and hydroxide is synthesized by performing a ligand etching strategy on FeMn co-doped Ni(OH) 2 nanosheets in situ grown on nickel foam (FeMn-Ni(OH) 2 @MOF/NF). Benefiting from the unique sheet-on-sheet hierarchical structure, multi-metal active nodes and two active materials grown in situ, the resulting FeMn-Ni(OH) 2 @MOF/NF demonstrated brilliant OER activity with an overpotential of 199 mV to achieve a current density of 10 mA cm -2 and long-term stability. This research will provide a new strategy for the design of high-performance OER electrocatalysts.

Although nanoporous materials have been fabricated by electrodeposition using micelles of P-123 as structure-directing entities, the possible geometry obtained has been limited to nanoporous films. Herein, a novel dual-template assisted electrodeposition method to fabricate Cu/Cu 2 O porous nanowires (PNs) using polymeric micelles as a soft template and polycarbonate membranes as a hard template is reported. These nanowires consist of a porous skeleton with nanosized pores of 20 nm on average and crystallized ligaments. Morphology, composition, and crystal structure are systematically investigated and the formation mechanism is discussed. The as-deposited Cu/Cu 2 O PNs are found to exhibit high electrocatalytic activity toward electroreduction of nitrate. At an applied cathodic potential of 0.53 V vs. the reference reversible hydrogen electrode, the selectivity for NH 3 conversion is 37.3%. Our approach is anticipated to work for the synthesis of PNs of other materials that could be obtained via electrochemical means., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Since the complicated multiple electron transfer process and slow kinetics in the OER process seriously hinder the electrochemical decomposition of water, it is urgent to design and develop electrocatalysts with excellent performance and superior stability to reduce overpotential and accelerate the reaction dynamics of the OER. Herein, a unique ultra-thin nanosheet bimetal electrocatalyst NiFe-MOF/IF was synthesized by a one-step hydrothermal method, and characterized by SEM, XRD, TEM, and XPS. NiFe-MOF/IF shows superior OER electrocatalytic activity in 1 M KOH electrolyte solution, and an ultralow overpotential of only 230 and 262 mV was required to achieve a current density of 10 and 100 mA cm -2 , respectively, with a relatively small Tafel slope of 30.46 mV dec -1 for the OER. No obvious degradation of the current density at 10 mA cm -2 was observed over about 16 h, which indicates the excellent stability of the catalyst. Favourable activity and benign durability of NiFe-MOF/IF can be attributed to the three-dimensional high porosity conductive substrates, in situ growth of MOF nanosheets, bimetallic synergy, and unique layering. This research provides a promising strategy for the application of MOF materials in the field of electrocatalysis.

The development of hydrogen evolution reaction (HER) electrocatalysts with outstanding efficiency and favorable stability at all pH values is of great significance but still a dominating challenge toward the development of electrochemical water-splitting technology. Herein, CoRu alloy nanoparticles assembled in Co 4 N porous nanosheets (named as CoRu@Co 4 N) have been successfully achieved from Ru(OH) 3 @Co(OH) 2 through a one-step nitridation process. Benefiting from the unique structure, inherent alloy properties and strong alloy-support interaction derived from the in situ transformation, the resultant hybrids exhibit superior HER activities over a wide pH range, achieving very low overpotentials of 13 mV, 44 mV and 15 mV at 10 mA cm -2 under alkaline, neutral and acidic conditions, respectively. Such activities surpass most reported electrocatalysts and are comparable or even transcendent to commercial Ru/C and Pt/C. Furthermore, CoRu@Co 4 N also exhibits outstanding stability during the accelerated degradation test (ADT) and chronopotentiometry. Our work provides a new approach for designing pH-universal Ru-involved HER electrocatalysts with remarkable efficiency and prominent durability.