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Transition metal nitrides (TMNs) have attracted great attention as ideal active materials in the field of electrocatalysts in recent years due to their excellent electrical conductivity, wide band gap and adjustable morphology. Pure phase Co 4 N nanoparticles encapsulated nitrogen-doped carbon (NC) nanotubes (Co 4 N@NC) were in-situ synthesized by one-pot method. In this paper, the morphology of carbon nanotubes is controlled by adjusting the pyrolysis time, so that more active sites are exposed on carbon nanotubes. Thus, the cobalt nitride catalyst with excellent catalytic performance for hydrogen evolution reaction (HER) in acidic electrolyte was obtained. In summary, due to the protection of mesoporous nitrogen-doped carbon to Co 4 N nanoparticles, large electrochemically active surface area, good conductivity and more exposed active sites, Co 4 N@NC possesses excellent HER performance in acidic electrolytes. The overpotential of Co 4 N@NC at the current density of 10 mA cm−2 is 117 mV (η 10), and it shows long-term stability in 0.5 M H 2 SO 4 solution for 50 h. This study provides a strategy for the development of catalysts for the controllable synthesis of high-performance transition metal nitrides. [Display omitted] [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS 2) exhibits the modest properties toward hydrogen evolution due to its poor electrical conductivity and a limited number of active sites. To make up for the defects in MoS 2 , we built hierarchical P-doped MoS 2 /NiS 2 @carbon hollow nanospheres (P–MoS/NiS@CHNS) electrocatalyst via one-step hydrothermal method owning to the priority of the reaction between Ni2+ and H 2 S. Motivated by high-efficient electron transfer at the interface of heterostructure and the activation of MoS 2 by P dopant, P–MoS/NiS@CHNS exhibits optimal Gibbs free energies (ΔG H∗) and superior HER performance with low overpotential (ƞ 10) of 110 ​mV ​at 10 ​mA ​cm−2 and small Tafel slope of 61 ​mV dec−1. The focus of this work is to optimize the HER performance of MoS 2 through P-doping and heterostructure construction, which can further provide a reference for the design of MoS 2 based catalysts. Image 1 • The P–MoS 2 /NiS 2 heterostructure is in favor of expeditious electrons transfer. • Thanks to the priority of the reaction between Ni2+ and H 2 S, the heterostructure was constructed. • The introduction of P optimizes the electron configuration of MoS 2. • The well-designed P–MoS/NiS@CHNS electrocatalyst has the optimal ΔG H∗ and E a value. [ABSTRACT FROM AUTHOR]

In this work, nickel cobalt bimetallic sulfide with typical multi-shell hollow sphere structure behaved superior electrocatalytic activity towards hydrogen evolution reaction (HER), which have been prepared through a easy method included solvothermal step, calcination step and in-situ sulfurization step. The composition and structure of the obtained nickel cobalt bimetallic sulfide are controlled through adjusting the sulfurization temperature and dosage of sulfur source. The as-prepared Ni–Co-S multi-shell hollow microspheres (abbreviated as Ni-Co-S) behaves superb HER properties in alkaline medium and Ni-Co-S-340(60) performs the most superior property, in which reflected the lowest overpotential (129 mV vs. RHE) at the current density of 10 mA cm−2 and the smallest Tafel slope (96.1 mV dec−1) among all the synthesized samples. The superior electrocatalytic performance of the obtained Ni-Co-S-340(60) for HER is owing to the unique multi-shell hollow structure derived from the intrinsic porous character of Ni-Co-BTC MOF precursor in one hand. And in the other hand, introducing highly active NiCo 2 S 4 into NiS 2 would enhance its elctrocatalytic activity because of the strong interfacial effect between NiS 2 and NiCo 2 S 4. Image 1 [ABSTRACT FROM AUTHOR]

[Display omitted] • Introducing Co and P to activate inert Cu-based nanowires to achieve efficient HER/OER. • Co-doped Cu 3 P nanospheres stacked into nanochains by through a valid approach. • Prepared catalyst has excellent HER/OER activity and long term stability. Developing durable, effective and inexpensive electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are crucial for the advancement of water splitting as a solution to the energy shortage. In this study, nanospheres stacked into nanochains are successfully prepared by oxidative corrosive engineering, solvothermal, and following calcination process (Co-Cu 3 P/CF). The unique nanochain structure facilitates growing the specific surface area, thereby exposing plenitude active sites. The introduced phosphorus (P) and Co ions can alter the electronic characteristics of metal phosphides, not only can accelerate the electron transport of the catalysts, but speed up the reaction kinetics. Thus, the prepared Co-Cu 3 P/CF exhibits low overpotentials, with 240/84 mV, in alkaline media for OER/HER to attain 10 mA cm−2. In alkaline freshwater/seawater, the self-assembled electrolyzer needs only 1.51/1.58 V to achieve 10 mA cm−2. This work provides an approach for the preparation of high-performing and economical electrocatalysts. [ABSTRACT FROM AUTHOR]

The development of phosphide-based electrocatalyst with excellent properties and good stability under both acidic and alkaline condition is the hotspot of recent research. Herein, we synthesized N doped CoP coated with carbon nanotubes (CoP@NC) electrocatalyst for hydrogen evolution reaction (HER), in which, the ZIF-67 (ZIF = zeolite imidazole skeleton) nanoparticles wrapped Co-MOF (MOF = metal-organic skeleton) nanorods has been used as precursor. The improvement of catalytic performance of N-doped CoP can be attributed to the fact that the introduction of N can optimize the electronic structure and the in-situ grown carbon nanotubes can improve charge transfer rate and avoid the agglomeration of active units. In addition, the effect of phosphorization temperature and the amount of carbon nanotube on the electrochemical activity of the samples were also investigated, and the obtained CoP@NCs only required low overpotential of 250 mV and 234 mV to drive the current density of 100 mA cm−2 under acidic and basic conditions, respectively. This work opens up an efficient paradigm for optimizing the performance of electrocatalysts. • N doped CoP coated with carbon nanotubes (CoP@NC) has been synthesized. • The in-situ formed carbon nanotubes could efficiently improve the charge transfer rate. • The use of Co-MOF in the core part could efficiently the accumulation of active phase. • The carbonization atmosphere has an obviously effect on the electrocatalytic performance. [ABSTRACT FROM AUTHOR]