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To improve the complexity and low catalytic performance and reduce the high cost of the traditional electrode preparation process for the sodium borohydride electro-oxidation reaction (BOR), in this work, a self-supported and efficient electrode material grown on nickel foam (CoNi/Co3O4/NF) was successfully designed using a simple hydrothermal synthesis method accompanied by the electrodeposition process. Benefiting from the three-dimensional nanoarray structure of CoNi/Co3O4/NF and the uniform distribution of Co and Ni modulating active sites by electrodeposition, the catalytic activity towards NaBH4 exhibits high efficiency. CoNi/Co3O4 exhibits excellent catalytic performance (up to 2157 mA cm−2 in 2 mol L−1 NaOH and 0.3 mol L−1 NaBH4), a high electrochemically active surface area (62.5 cm−2), and a low activation energy (15.56 kJ mol−1). The CoNi/Co3O4/NF electrode was further investigated on a direct sodium borohydride–hydrogen peroxide fuel cell (DBHPFC), which exhibited a maximum power density of 108.5 mW cm−2 and excellent stability. The excellent performance is mainly due to its unique nanoarray structure and electrodeposition distribution of Co and Ni active sites, which increases the electrochemical surface area and enhances the contact between the electrode and the electrolyte. [ABSTRACT FROM AUTHOR]

Urea electrolysis is an appealing energy conversion technology to produce hydrogen (H2) and alleviate the problem of urea-rich wastewater treatment concurrently. In particular, electrocatalytic performance can be dramatically enhanced by rationally modulating the surface charge distribution with a well-tuned heterostructure. Herein, a heterostructure is constructed by NiMoO4 nanosheets grown on an interior hollow NiS@Ni3S2 nanorods framework (NiS@Ni3S2/NiMoO4). Density functional theory (DFT) calculations demonstrate that the formed heterojunction structure leads to a tailored surface charge state of NiMoO4, with oxygen as the nucleophilic region and molybdenum as the electrophilic region, which facilitates the decomposition of urea molecules and thus significantly improves hydrogen evolution. As expected, the assembled NiS@Ni3S2/NiMoO4 system substantially expedites urea electrolysis activity with a cell voltage of 1.40 V at 10 mA cm−2, which is 200 mV less than the voltage of an overall water splitting system. [ABSTRACT FROM AUTHOR]

Herein, a three-dimensional (3D) Ni/Fe bimetallic organic framework (MOF-Ni@MOF-Fe) with a structure of rhombus blocks on nanosheets is synthesized on Ni foam by a 2-step solvothermal method. After sulfide reaction, MOF-Ni@MOF-Fe–S is vulcanized by MOF-Ni@MOF-Fe with a structure of interwoven and folding nanosheets. Meanwhile, Ni3S2 is formed under the influence of iron. This special structure makes MOF-Ni@MOF-Fe–S to expose more active sites. MOF-Ni@MOF-Fe–S shows superior urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) performance. When MOF-Ni@MOF-Fe–S is used as UOR and HER catalysts, it has low potentials of 1.347 V (vs. RHE) at 10 mA cm−2 and 0.145 V (vs. RHE) at 10 mA cm−2 in 1.0 M KOH with 0.5 M urea, respectively. MOF-Ni@MOF-Fe–S as a bifunctional electrode is assembled as an alkaline urea electrolyzer, showing catalytic activity at a low cell voltage of 1.539 V at 10 mA cm−2 and excellent stability during 10 h chronopotentiometry analysis. [ABSTRACT FROM AUTHOR]

Urea electrolysis offers the prospect of cost-effective and energy-saving hydrogen production together with mitigating urea-rich wastewater pollution instead of overall water splitting. Hence, here, high-efficiency bifunctional electrocatalysts were developed for both the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) via the in situ vertical growth of thorny leaf-like (2D nanosheets supporting 1D nanowires) NiCoP on a carbon cloth (NiCoP/CC). After integrating the advantages of the synergistic effect between Ni and Co as well as the unique hierarchical structure combined with 1D nanowires, 2D nanosheets and a 3D conductive carbon cloth substrate, the electrode exhibited excellent electrocatalytic activity toward HER and UOR. The electrolytic cell assembled using NiCoP/CC as the anode and the cathode could provide current density of 10 mA cm−2 at a cell voltage of 1.42 V (160 mV less than that for its urea-free counterpart) as well as remarkable durability over 30 h. Thus, the cost-effectiveness and high activity of the NiCoP/CC electrode pave the way to explore transition metal-based electrocatalysts for urea electrolysis. [ABSTRACT FROM AUTHOR]

Large surface area, high electrical conductivity, and abundant channels have been recognized to favor faradic capacitors, but their realization at the same time by a facile preparation process is still a great challenge. Here, we synthesized porous cadmium sulphide freely standing on nickel foam (CdS/NF) via a one-step hydrothermal method which possesses high specific capacitance, good rate capability and outstanding cycling stability. The CdS/NF microspheres present pores with a mean size of ∼3 nm, resulting in fast diffusion of ions, facile transportation of electrons and high activity, which make great synergistic contributions to reversible redox reactions. In the resulting supercapacitors, a specific capacitance of 909 F g−1 is achieved at a current density of 2 mA cm−2 with excellent rate capability that 88% of the original capacitance is retained at 50 mA cm−2. After 5000 charge–discharge cycles at current densities as large as 50 mA cm−2, 104% of initial capacitance is maintained. Finally, asymmetric supercapacitors with a high energy density of 28 W h kg−1 at a power density of 160 W kg−1 were obtained. [ABSTRACT FROM AUTHOR]

A low-cost and binder-free cobalt electrode is prepared by the electrodeposition of Co nanoplates onto a flexible conductive substrate, which is prepared simply by scratching a piece of A4 paper with a common 8B pencil. The morphology and phase structure of the cobalt–graphite–paper (CGP) electrode are characterized by scanning electron microscopy, transmission electron microscopy and an X-ray diffractometer. The catalytic activity of the CGP electrode for NaBH4 electro-oxidation is investigated by cyclic voltammetry and chronoamperometry. The catalyst combines tightly with the paper and exhibits a good stability. The oxidation current density reaches up to 180 mA cm−2 in 1 mol dm−3 NaOH and 0.10 mol dm−3 NaBH4 at −0.4 V. [ABSTRACT FROM AUTHOR]

In this work, a facile method for the preparation of a series of transition metal oxide–metal nanocomposites (MO–M) (such as NiO–Ni, Co3O4–Co, Fe3O4–Fe and MnO2–Mn) anchored on conductive nanowire arrays (such as TiC–C core–shell nanowires grown on a Ti alloy sheet) is reported for the first time. The obtained composites possess a unique three-dimensional nanostructure and high electronic conductivity. They have diverse applications as electrodes of energy storage devices. High capacitance and high rate capability have been demonstrated using the NiO–Ni@C@TiC nanocomposite as a model electrode, which shows a specific capacitance as high as 1845 F g−1 at a charge–discharge current density of 5 A g−1 and 811.1 F g−1 after cycling 500 times at an extremely high charge–discharge rate of 100 A g−1. [ABSTRACT FROM AUTHOR]

Potassium-ion batteries (PIBs) as a promising and low-cost battery technology offer the advantage of utilizing abundant and cost-effective K-salt sources. However, the effective adoption of PIBs necessitates the identification of suitable electrode materials. The 1T phase of MoS 2 exhibits enhanced electronic conductivity and greater interlayer spacing compared to the 2H phase, leading to a capable potassium ion storage ability. Herein, we fabricated dual carbon engineered 1T/2H MoS 2 via a secure and straightforward ammonia-assisted hydrothermal method. The 1T/2H MoS 2 @rGO@C structure demonstrated an expanded interlayer spacing (9.3 Å). Additionally, the sandwich-like structural design not only enhanced material conductivity but also effectively curbed the agglomeration of nanosheets. Remarkably, 1T/2H MoS 2 @rGO@C exhibited impressive potassium storage ability, delivering capacities of 351.0 mA h g -1 at 100 mA g -1 and 233.8 mA h g -1 at 1000 mA g -1 following 100 and 1000 cycles, respectively. Moreover, the construction of a K-ion full cell was successfully achieved, utilizing perylene tetracarboxylic dianhydride (PTCDA) as the cathode, and manifesting a capacity of 294.3 mA h g -1 at 100 mA g -1 after 160 cycles. This underscores the substantial potential of employing the 1T/2H MoS 2 @rGO@C electrode material for PIBs.

Herein, a three-dimensional (3D) Ni/Fe bimetallic organic framework (MOF-Ni@MOF-Fe) with a structure of rhombus blocks on nanosheets is synthesized on Ni foam by a 2-step solvothermal method. After sulfide reaction, MOF-Ni@MOF-Fe-S is vulcanized by MOF-Ni@MOF-Fe with a structure of interwoven and folding nanosheets. Meanwhile, Ni 3 S 2 is formed under the influence of iron. This special structure makes MOF-Ni@MOF-Fe-S to expose more active sites. MOF-Ni@MOF-Fe-S shows superior urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) performance. When MOF-Ni@MOF-Fe-S is used as UOR and HER catalysts, it has low potentials of 1.347 V (vs. RHE) at 10 mA cm -2 and 0.145 V (vs. RHE) at 10 mA cm -2 in 1.0 M KOH with 0.5 M urea, respectively. MOF-Ni@MOF-Fe-S as a bifunctional electrode is assembled as an alkaline urea electrolyzer, showing catalytic activity at a low cell voltage of 1.539 V at 10 mA cm -2 and excellent stability during 10 h chronopotentiometry analysis.