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Herein, a brush-like Cu2O–CoO core–shell nanoarray on copper foam (Cu2O–CoO/CF) can achieve efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance in alkaline seawater electrolyte. This Cu2O–CoO/CF shows overpotentials as low as 315 and 295 mV at 100 mA cm−2 for the OER and HER, respectively. Moreover, it could also be operated at 1.82 V with 100 mA cm−2 in a two-electrode electrolyzer and exhibits strong stability for at least 50 hours of electrolysis. The excellent performance and hierarchical structure advantages of Cu2O–CoO/CF provide new ideas for designing efficient seawater splitting electrocatalysts. [ABSTRACT FROM AUTHOR]

High‐performance low‐cost hydrogen evolution electrocatalysts are urgently demanded for hydrogen production by water splitting. Herein, we report that an efficient defect engineering strategy, NaBH4 treatment, was employed to promote the HER activity of pre‐synthesized Mo‐doped V1.11S2 nanosheets. The abundant sulfur vacancies enable Mo‐doped V1.11S2 petaloid nanosheets with a low overpotential of 160 mV and a small Tafel slope of 46.2 mV dec−1 at 10 mA cm−2 to drive the HER, as well as excellent long‐term stability in 0.5 mol L−1 H2SO4. The outstanding electrocatalytic performance can be attributed to the large electrochemical surface area and low charge transfer resistance. [ABSTRACT FROM AUTHOR]

High‐performance earth‐abundant electrocatalysts for oxygen evolution reaction (OER) are highly desirable. In this report, we successfully synthesized amorphous Fe−P shell electrodeposited on Co(OH)F nanowire arrays supported on titanium mesh (Fe−P@Co(OH)F/TM) as an efficient catalyst for OER. Such catalyst exhibits excellent OER activity with a low overpotential of 267 mV to reach the geometrical current density of 10 mA cm−2 in 1.0 M KOH. In addition, it has good electrochemical durability to maintain its activity for at least 20 h. [ABSTRACT FROM AUTHOR]

Ni–Cu alloy-based nanomaterials are representative cost-effective materials that have been widely used as highly active and stable electrocatalysts for electrochemical energy applications, such as the water oxidation reaction, the methanol/ethanol reaction and many other small molecule oxidation reactions. Here, novel short needle-like complex oxides of NixCu1−x/CuO/Ni(OH)2 are rationally designed and synthesized to further promote their oxygen evolution reaction (OER) performance. Under the tuning of electron perturbation and surface morphology, Ni0.7Cu0.3/CuO/Ni(OH)2 reached an optimum performance of ∼136.6 mVRHE kinetic potential and ∼160 mVRHE (vs. 3.33 A g−1) over-potential with a Tafel slope of 66 mV dec−1. Furthermore, the complex oxides are directly grown on glass carbon, which works as a binder-free and carbon-free electrode, leading to an excellent stability of 200 000 s with 39% activity loss. Due to the electron perturbation role of Cu as well as the synergistic interactions among Ni–Cu, CuO and Ni(OH)2, the obtained Ni0.7Cu0.3/CuO/Ni(OH)2 complex oxide is significantly more active and stable than those of NixCu1−x alloy, CuO and Ni(OH)2. Our results demonstrate a general strategy to design cost-efficient OER electrocatalysts by using a conventional and easily accessible Ni0.7Cu0.3/CuO/Ni(OH)2 hybrids to possibly replace commercial Ru/Ir-based materials. [ABSTRACT FROM AUTHOR]

FeCoNi spinel oxides nanosheets array directly supported on the Ni foam substrate were prepared via a facile wet chemical method with 2‐methylimidazole as a structure directing agent and subsequently annealing. The as‐prepared 0.1Fe−CoNiO/NF offers high intrinsic catalytic activity, high surface area and good conductivity, resulting in enhanced activity for the oxygen evolution reaction (OER) in the alkaline solution. It demonstrates an ultralow overpotentials of 240 mV at 10 mA cm−2 and a small Tafel slope of 36.8 mV dec−1, with attractive durability during long‐term operation in 1 M KOH solution. [ABSTRACT FROM AUTHOR]

Electrons released from surface reactions need to be transferred quickly to avoid the inhibition for following reactions. Herein, a novel strategy has been demonstrated to achieve outstanding catalytic performance for oxygen evolution reaction (OER), specifically removing interfacial charges through an optimized hybrid amorphous/crystalline FeNi (Oxy)hydroxides. Such hybrid structure offers an overpotential of only 215 mV at the current density of 10 mA cm−2 and a Tafel slope of 50.9 mV dec−1 in 1 M KOH, together with outstanding stability. The superior catalytic activity and stability can be attributed to the unique amorphous/crystalline microstructure, leading to optimized reactivity and excellent conductivity. [ABSTRACT FROM AUTHOR]

In the present study, we present a facile strategy to synthesis Co3O4 materials with different morphology. Experimental results show that Co3O4 materials with flower-like, fiber, sheet-like and rod morphologies have been successfully prepared by hydrothermal synthesis in different solvent. The effect of the morphology on the electrochemical catalytic properties were also studied. It is found that sheet-like Co3O4 exhibits the best activity towards oxygen evolution reaction (η10 = 390 mV) in 1 M KOH, which can be attribute to its short electrolyte infiltration diffusion path lengths and low charge transfer resistant.Graphical Abstract: LSV curves measured at 5 mV/s in 1 M KOH solution for OER, the inset image is FE-SEM image of prepared Co3O4 materials. a Flower, b fiber, c sheet and d rod. [ABSTRACT FROM AUTHOR]

Conclusion: We report a series of binder-/carbon-free and non-precious Fe x Co 1-x /CoOOH/FeOOH (FCH-x) Hybrids as a promising material to overcome these problems, which exist in OER. We find that FCH-3 retains an excellent mass activity of ∼11.9 A g−1 even after 58 h i-t measurements. [Display omitted] • A series of binder- and carbon-free Fe x Co 1-x /CoOOH/FeOOH OER catalysts is developed. • The role of composition effect on OER performance is investigated. • The Fe 0.3 Co 0.7 /CoOOH/FeOOH alloy has extra-long OER durability (58 h). • The relationship of ESCA evolution and OER activity change of Fe 0.3 Co 0.7 /CoOOH/FeOOH alloy is captured. Ru/Ir-based precious catalysts are considered to be the state-of-the-art catalysts toward high performance anode for electrochemical oxygen evolution applications, owing to their high intrinsic activity for oxygen evolution reaction (OER). However, the current major barrier for their commercialization is high-cost and low durability of them at high OER potential. Here, we report a series of binder-/carbon-free and non-precious Fe x Co 1-x /CoOOH/FeOOH (FCH-x) hybrids as a promising material to overcome these problems. On the one hand, the Fe x Co 1-x framework can effectively enhance the electrical conductivity of FCH-x and generate fresh CoOOH/FeOOH to self-supplementary, providing an ideal platform to improve the durability of FCH-x. On the other hand, in analogy to typical alloys in OER, the composites modification and d-band tuning of Fe x Co 1-x in this work is expected to enhance the activity of FCH-x. As a result, FCH-7 retains an excellent mass activity of ∼ 11.9 A g−1 even after 58 h i-t measurements. Most strikingly, compared to the pure Co, the d-band center of FCH-7 is positive shifted ∼ 0.4 eV owing to the surface oxyhydroxides, which may be one reason for activity enhancement. Our demonstration of FCH-7/GC with unique properties of carbon- and binder- free, self-supplementary, self-enhancing, and d-band center balancing opens up a new avenue for developing high activity and durable OER catalysts towards practical of oxygen preparation. [ABSTRACT FROM AUTHOR]

• Fe doped Ni 3 S 2 /NF were prepared via a facile hydrothermal method. • The OER performance of Ni 3 S 2 /NF was significantly enhanced after Fe doping. • A small PDS for doped Ni 3 S 2 /NF of 0.31 eV can be obtained at the Fe site. Transition metal sulfides are one of the most efficient earth-abundant oxygen evolution reaction (OER) electrocatalysts. In the present study, Fe doped Ni 3 S 2 nanosheets have been directly grown on nickel foam via a facile hydrothermal process. The OER electrocatalytic activity of Fe-Ni 3 S 2 /NF can be enhanced by adjusting the addition amount of Fe. It requires an overpotential of 246 mV to afford a current density of 20 mA cm−2 and a Tafel slope of 66 mV dec−1, significantly lower than that of Ni 3 S 2 /NF electrode. This catalyst is highly stable, showing a slight overpotential rise of 15.1 mV over continuous testing for 20 h. In addition, combine EIS measurement and density functional theory calculations, revealing that Fe doped Ni 3 S 2 /Ni electrodes have both high conductivity and excellent intrinsic activity, leading to a promising OER electrocatalytic activity. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) catalyzed by Ru/Ir-free electrocatalysts is pivotal for preparing oxygen in efficient way, yet our understanding of the relationship between microphysical properties and OER performance is still insufficient. Here we report on 41 kinds of Fe x Cu y Ni 1-x-y /FeOOH/NiOOH/CuO complexes (FCN-x) to investigate the Cu and Fe induced electronic perturbation and what it brings to OER performance. As result, the activity mapping of FCN-x shows an optimal composition of 1:2:7 (FCN-7) showing a comparable overpotential potential of 170.3 mV, Tafel slop of 75.9 mV dec−1 and durability of 24 h (∼29% activity loss) to that of mainstream Ru/Ir-free catalysts. Such enhancement could be attributed to the role of alloying contribution of Fe/Cu, electronic perturbation and surface modification of surface oxides. Additionally, the incompletely oxidized Fe x Cu y Ni 1-x-y not only provide a platform for electron conduction, but also work as a sacrificial material to forming fresh oxides to maintain the content of surface oxides, which is a key driver of the excellent durability of FCN-7. This synthetic strategy may give an effective way to design and screen Ru/Ir-free OER catalysts. A platform guideline for designing Fe x Cu y Ni 1-x-y /FeOOH/NiOOH/CuO Complex Oxides is reported. The screened FCN-7 electrocatalysts exhibit not only high OER activity but also superior stability. Its OER performance, and working mechanism is investigated. The FCN-7 with unique composition tuning, species controlling, and electronic structure modification would open up a new avenue for designing high activity and durable Ir-/Ru-free OER catalyst. [Display omitted] • 41 kinds of Fe x Cu y Ni 1-x-y was prepared by the electrodeposition method with accurate composition control. • The composition optimization and electron perturbation play a key role on activity modification. • There are two optimum compositions existed over 41 kinds of Fe x Cu y Ni 1-x-y. • The Fe 0·1 Cu 0·2 Ni 0.7 showed the best oxygen evolution reaction activity and durability. [ABSTRACT FROM AUTHOR]

[Display omitted] • NFO-x complexes is directly deposited on glassy carbon that avoid the binder-age and carbon-corrosion on high working potential. • NFO-x complexes is reasonably prepared with surface species of Ni(OH) 2 and Fe 2 O 3 through a two-step electrochemical process. • Elucidate the relationship of surface composition/electronic structure and OER activity. • The novel stability of NFO-0.6 probably induced by the surface oxides and the metallic Ni x Fe 1−x transforming during long-term operation. NiFe-based oxygen evolution reaction (OER) electrocatalysts, as a typical non-precious material on water splitting, has attracted more attention because of their high OER performance and high reserves. But in terms of large-scale production and application, the "manufacturing costs" and "controllability" of NiFe-based catalysts are still the barrier of them. Here we demonstrate how the cationic (Fe3+/Ni2+) concentration of precursor solution-terminated Ni x Fe 1−x /Fe 2 O 3 /Ni(OH) 2 complexes dictates the durability and activity of the OER via an electrodeposition method. The results indicated that the OER performance and manufacturing costs can be optimized easily with this industrialized method. Specifically, the optimized Ni 0.6 Fe 0.4 /Fe 2 O 3 /Ni(OH) 2 complex (NFO-0.6) showed the best OER performance of 218 mV overpotential, 122 mV·dec−1 Tafel slop, 12 h long-term operation with ∼ 38% activity loss. The activity evolution tread suggests that the novel stability of NFO-0.6 is probably induced by the surface oxides and the metallic Ni x Fe 1−x transforming during long-term operation(Ni x Fe 1−x → Fe 2 O 3 /Ni(OH) 2). Our work thus demonstrates the tunability of NFO-x activity and durability by controlling the cationic (Fe3+/Ni2+) concentration of precursor showing enormous potential to promote the practical application in water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • A binder- and carbon-free OER catalyst of a series of Co x Cu 1-x alloys is developed. • The role of composition controlling and electronic perturbation on OER performance is investigated. • The catalyst reconstruction process, during OER, is investigated. • Surface oxygen containing substances not only promote the activity of Co x Cu 1-x alloys, but also increase the durability. • The role d-band center shifting on OER activity of Co x Cu 1-x alloys is captured. The design of high efficiency, low cost and abundant sources electrocatalysts for oxygen evolution reaction (OER) has attracted more and more attention, because of the depletion of precious and rare metals. Herein, we reported a highly active Co 0.7 Cu 0.3 alloy, which screening from a series of Co x Cu 1-x alloys (x = 0.1–0.9) via surface composition controlling and electron state modification. Compared with the Co, other Co x Cu 1-x alloys, as well as commercial RuO 2 /IrO 2 , the Co 0.7 Cu 0.3 catalyst exhibited very high activity in electrocatalytic O 2 production from alkaline solution (∼207 mV overpotential). Meanwhile the Co 0.7 Cu 0.3 catalyst exhibited excellent durability for OER, after 72,000 s operation, the attenuation rate of Co 0.7 Cu 0.3 catalyst is lower than ∼ 20%. The high catalytic activity of Co 0.7 Cu 0.3 is attributed to positive shift of d-band center and surface species of Co 0.7 Cu 0.3 alloy which facilitates oxygen-containing species (OCS) formation (*H 2 O 2 , *OOH, *OH) and electron transfer. This method of improving the catalytic performance by adjusting the alloy composition to achieve the microscopic electronic perturbation effect is expected to attract attention in the later research. [ABSTRACT FROM AUTHOR]