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Highlights: Plasma-assisted phosphorization has been used to prepare defect-rich metal phosphides. The p-NiCoP/NCF@CC shows high activities and excellent stability for the hydrogen evolution reaction and the oxygen evolution reaction. The p-NiCoP/NCF@CC shows great potential for overall water splitting. This work reports the use of defect engineering and carbon supporting to achieve metal-doped phosphides with high activities and stabilities for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline media. Specifically, the nitrogen-doped carbon nanofiber-supported Ni-doped CoP3 with rich P defects (Pv·) on the carbon cloth (p-NiCoP/NCFs@CC) is synthesized through a plasma-assisted phosphorization method. The p-NiCoP/NCFs@CC is an efficient and stable catalyst for the HER and the OER. It only needs overpotentials of 107 and 306 mV to drive 100 mA cm−2 for the HER and the OER, respectively. Its catalytic activities are higher than those of other catalysts reported recently. The high activities of the p-NiCoP/NCFs@CC mainly arise from its peculiar structural features. The density functional theory calculation indicates that the Pv· richness, the Ni doping, and the carbon supporting can optimize the adsorption of the H atoms at the catalyst surface and promote the strong electronic couplings between the carbon nanofiber-supported p-NiCoP with the surface oxide layer formed during the OER process. This gives the p-NiCoP/NCFs@CC with the high activities for the HER and the OER. When used in alkaline water electrolyzers, the p-NiCoP/NCFs@CC shows the superior activity and excellent stability for overall water splitting. [ABSTRACT FROM AUTHOR]

Despite significant progress, precise control of the dispersion of ruthenium (Ru) nanoparticles (NPs) on the carrier, reduction of their aggregation and leaching during water splitting is always a challenging issue. In this work, metal-organic frameworks (MOFs) derived Co 7 Fe 3 alloy/Co NPs embedded in nitrogen-doped carbon and nitrogen-doped carbon nanotubes (FeCoSG/NCNT) with a three-dimensional (3D) spider-egg structure are synthesized by chemical vapor deposition (CVD) technique. Then, Ru NPs are uniformly loaded on the FeCoSG/NCNT through impregnation and reduction. The obtained FeCoSG/NCNT@Ru possesses enriched mesopore and high conductivity. In addition, the Ru NPs synergize with non-precious metal active sites to promote hydrogen-evolution-reaction (HER), which lowers the need for precious metals while maintaining excellent performance. The obtained FeCoSG/NCNT@Ru only requires a low overpotential of 21.1 mV to attain a current density of 10 mA cm−2 in 1 M KOH towards HER, which is smaller than the benchmark catalyst Pt/C (∼30.1 mV). Moreover, it shows ultra-high stability, which can work continuously at current densities of 10, 20, and 30 mA cm−2 for 25 h without degradation, respectively. The study presents insight on the design of advanced support and the construction of highly active and durable electrocatalysts. [Display omitted] • Co 7 Fe 3 alloy/Co NPs embedded in MOF-derived NC encapsulated by NCNT. • The N doping brings a favorable effect on the regulation of Ru distribution. • The unique spider-egg structure provides an abundance of Ru attachment sites. • FeCoSG/NCNT@Ru is a highly efficient and stability HER catalyst. • It exhibits an extremely small overpotential of 21.1 mV at 10 mA cm−2. [ABSTRACT FROM AUTHOR]

A plasma approach is reported to synthesize carbon cloth supported carbon fiber and oxygen defect‐rich NiCoO/NiCoN hetero‐nanowire co‐integrated hybrid catalyst (P‐NCO/NCN‐CF@CC), which includes the advanced features of carbon integration, cation doping, defect/vacancy introduction, and heterostructuring. The P‐NCO/NCN shows a fascinating structure with the periphery composed of NCO and the interior co‐composed of NCO and NCN. Its formation mainly depends on the high reactivity of energetic species of NH, Ha, and Hb formed during the plasma discharge. The P‐NCO/NCN‐CF@CC exhibits the oxygen reduction reaction (ORR) activity comparable to the Pt/C and the oxygen evolution reaction (OER) activity higher than RuO2. When used in the all‐solid‐state zinc‐air batteries, it gives a high maximum power density of 109.8 mW cm−2 with no performance drop observed for >300 cycles. The DFT calculations indicate that the NCO/NCN heterostructuring and oxygen defects in NCO play the important roles in the high ORR/OER activities of the catalyst. They can modulate the electronic structure of the catalyst, lowering the energy barriers of rate determining steps. [ABSTRACT FROM AUTHOR]

Developing acid‐stable electrocatalysts with high activity for the oxygen evolution reaction (OER) is of paramount importance for many energy‐related technologies. This work reports that ultrathin nitrogen‐doped carbon coated oxygen‐vacancy (Vo·) rich RuO2 nanoparticles on carbon nanotubes (CNTs) (NC@Vo·‐RuO2/CNTs‐350), synthesized through the controlled calcination in air, is an efficient acid‐stable electrocatalyst for the OER. It only needs an overpotential of 170.0 mV to drive 10.0 mA cm−2 and shows excellent stability with no distinguishable activity loss observed for >900 h. Its mass activity is >110 times higher than the commercial RuO2. In particular, an electrolyzer assembled with this catalyst shows a record‐low cell voltage of 1.45 V to deliver 10.0 mA cm−2 and exhibits a low performance drop for >1000 h. The NC@Vo·‐RuO2/CNTs‐350 also shows super‐high catalytic activities and excellent stabilities for OER in neutral and alkaline media. DFT calculations indicate that its high catalytic activity mainly arises from the strong electronic coupling between RuO2 and NC/CNTs, which increases the oxidation state and catalytic activity of Ru at the active site and improves the stabilities of lattice oxygen and surface Ru during the OER processes. The presence of Vo· can strengthen the electronic coupling between RuO2 and NC/CNTs. [ABSTRACT FROM AUTHOR]

• P-doped aminated CNTs supported CoP/NiCoP hetero-nanoparticles (CoP/NiCoP@P-ACNTs) is prepared. • The in-situ phosphorization from the single phase material enables the formation of the CoP/NiCoP heterostructure. • It is demonstrated to be an efficient and stable catalyst for HER over the universal pH range. • The high catalytic activities arise from the strong electronic couplings between CoP, NiCoP, and P-ACNTs. • It can make the ΔGH* value of the CoP/NiCoP@P-ACNTs close to zero and lower the energy barrier for water dissociation. Developing an efficient catalyst for pH-Universal hydrogen evolution is of great interest. This work reports the synthesis of P-doped aminated CNTs supported CoP/NiCoP hetero-nanoparticles (CoP/NiCoP@P-ACNTs) through the in-situ phosphorization of the single phase NiCo 2 O 4 grown on the ACNTs. The in-situ phosphorization from the single phase material enables the formation of the CoP/NiCoP heterostructure, facilitating an electronic coupling between CoP and NiCoP. The CoP/NiCoP@P-ACNTs is demonstrated to be an efficient and stable catalyst for the hydrogen evolution reaction (HER) over the universal pH range. Specifically, it only needs overpotentials of 26.0, 94.0, and 76.8 mV to drive the current density of 10 mA cm−2 in the acidic, neutral, and alkaline solutions, respectively. All of these values are close to those of Pt/C and lower than those of many other catalysts reported recently. The DFT calculations indicate that the high catalytic activities of the CoP/NiCoP@P-ACNTs for the HER arise from the electronic couplings between CoP, NiCoP, and P-ACNTs. They can make the ΔG H* value of the CoP/NiCoP@P-ACNTs close to zero and lower the energy barrier for water dissociation. The CoP/NiCoP@P-ACNTs derived from the in-situ phosphorization of the single phase NiCo 2 O 4 is demonstrated to be an efficient pH-universal catalyst for the HER, which arises from the strong electronic couplings between CoP, NiCoP, and P-ACNTs. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The CoNiFe 0.08 -NC@p-NCNTs is synthesized by DBD plasma treatment. • NC encapsulated CoNiFe NPs constructed nanosheets distribute on the network of NCNTs. • The CoNiFe 0.08 -NC@p-NCNTs is demonstrated to be an excellent catalyst for ORR/OER. • It shows great potentials in improving the performance of rechargeable ZABs. • The assembled flexible all-solid-state ZAB exhibits a high OCV of 1.384 V. Economical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional catalysts with high activity aimed at replacing precious metal catalysts for rechargeable zinc-air batteries (ZABs) must be developed. In this study, a multiple hierarchical-structural material is developed using a facile dielectric barrier discharge (DBD) plasma surface treatment, solvothermal reaction, and high-temperature carbonization strategy. This strategy allows for the construction of nanosheets using nitrogen-doped carbon (NC) material-encapsulated ternary CoNiFe alloy nanoparticles (NPs) on a network of NC nanotubes (NCNTs), denoted as CoNiFe–NC@p–NCNTs. Precisely, the presence of abundant CoNiFe alloy NPs and the formation of M–N–C active sites created by transition metals (cobalt, nickel, and iron) coupled with NC can provide superior OER/ORR bifunctional properties. Moreover, the prepared NC layers with a multilevel pore structure contribute to a larger specific surface area, exposing numerous active sites and enhancing the uniformity of electron and mass movement. The CoNiFe 0.08 –NC@p–NCNTs show remarkable dual functionality for electrochemical oxygen reactions (ORR half-wave potential of 0.811 V, limiting current density of 5.73 mA cm−2 measured with a rotating disk electrode at a rotation speed of 1600 rpm, and OER overpotential of 351 mV at 10 mA cm−2), which demonstrates similar ORR performance to 20 wt% Pt/C and better OER performance than the commercial RuO 2. A liquid ZAB prepared using the proposed material has excellent bifunctionality with an open-circuit voltage of 1.450 V and long-term cycling stability of 230 h@10 mA cm−2. [ABSTRACT FROM AUTHOR]

The development of highly-efficient and noble-metal-free catalysts with low cost and high durability for hydrogen evolution reaction (HER) is of great importance to many energy-related technologies. This work reports that nitrogen-doped carbon coated Co nanoparticles encapsulated in bamboo-like nitrogen-doped carbon nanotubes (Co@NC/B-NCNTs), synthesized by a simple calcination of Co(NO 3) 2 , melamine and P123, is a promising catalyst for HER in both acidic and alkaline solutions. In acidic solution, the Co@NC/B-NCNTs has the HER onset potential of ∼0 V and only needs an overpotential of 7 mV to drive the current density of 10 mA cm−2. Its HER catalytic activity is very close to that of Pt/C. In alkaline solution, its onset potential and overpotential to drive 10 mA cm−2 are 100 and 182 mV, respectively. Both the values are lower than those of many other catalysts reported. The DFT calculations show electronic coupling between Co nanoparticles and NC layer plays an important role in high catalytic activity of Co@NC/B-NCNTs. The Co nanoparticles can change the charge density distribution of the outer NC layer, affecting its properties for hydrogen adsorption and desorption. Additionally, the pyridinic N in the outer NC layer is calculated to be a promising active site for HER. The Co@NC/B-NCNTs has demonstrated to be an active catalyst for the HER in both the acidic and alkaline solutions, with the activity comparable to that of the Pt/C in the acidic solution. Image 1 • Nitrogen doped carbon coated Co nanoparticles encapsulated in bamboo-like nitrogen doped carbon nanotubes is synthesized. • Co@NC/B-NCNTs) is highly active for the HER in both the acidic and alkaline solutions. • Its HER catalytic activity is very close to that of the Pt/C, a benchmark catalyst for the HER. • The Co nanoparticles can change the charge density distribution of the outer NC layer, reducing the.|ΔG H∗ | value for hydrogen adsorption and desorption. • The calculation shows that the pyridinic N in the outer NC layer can be a promising active site for the HER. [ABSTRACT FROM AUTHOR]

Herein, Co 2 Mo 3 O 8 /Nb 2 O 5 heterojunctions with rich oxygen vacancies wrapped in cobalt embedded carbon hollow cubic nanoboxes (Co(Mo,Nb)@MCNBs) derived from metal-organic frameworks (MOFs) is synthesized by hydrothermal reaction, bimetallic cation doping, high-temperature carbonization. The synergistic effect and strong electron coupling interaction between Co 2 Mo 3 O 8 /Nb 2 O 5 heterojunctions and cobalt embedded carbon hollow cubic nanoboxes result in a more uniform distribution of heterojunctions on the surface of Co@MCNBs, more catalytic active sites are exposed and the catalytic performance is improved. It only requires an overpotential of 284 mV to drive the current density of 10 mA cm−2 towards oxygen evolution reaction (OER), which is significantly lower than most previously reported catalysts and commercial RuO 2. Furthermore, the Co(Mo,Nb)@MCNBs exhibits exceedingly good long-term stability with the current density retention rate of 98.1% after 43,200 s for OER, which even still outperform the commercial RuO 2 catalyst. More interestingly, the electrolyzer Co(Mo,Nb)@MCNBs(+)||Co@MCNBs(-) demonstrates an excellent cycling stability and outperforms RuO 2 (+)||Pt/C(-), suggesting the actual availability of Co(Mo,Nb)@MCNBs in overall water splitting. The synergic effect of heterostructures design of the Co(Mo,Nb)@MCNBs catalyst for overall water splitting will promote the mass production of hydrogen with high-efficiency and low-cost. [Display omitted] • A bimetal cation doping technique is used to grow Co 2 Mo 3 O 8 /Nb 2 O 5 heterojunction. • The designed electrode material Co(Mo,Nb)@MCNBs is rich in oxygen vacancies. • It has a rich hierarchical heterogeneous structure and high specific surface area. • It is an excellent catalyst with efficient and stable OER catalytic performance. • The two-electrode electrolyzer exhibits good performance and excellent stability. [ABSTRACT FROM AUTHOR]

In this work, plasma under different atmospheres is used to adjust the surface electronic and chemical structure of Fe/Co/N co-decorated hollow graphene spheres (FCNHGS) in order to create suitable conditions for the deposition of Pt 1 Ni 2 alloy nanoparticles (NPs). The results show that plasma treatment in specific atmospheres has different effects on the surface of FCNHGS, such as O 2 plasma is etching and oxidation, N 2 plasma and Ar plasma is etching, Ar/H 2 plasma is etching and reduction, Ar/NH 3 plasma is etching, doping and reduction. Therefore, changing the plasma treatment atmosphere can control the anchoring sites on FCNHGS for the deposition of Pt 1 Ni 2 NPs. When Ar/NH 3 plasma is used, the synthesized Pt 1 Ni 2 @Ar/NH 3 -FCNHGS exhibits the best bi-functional catalytic activity and the highest utilization efficiency of Pt in the oxygen reduction and hydrogen evolution reaction (ORR/HER) due to the strong interaction between loaded Pt 1 Ni 2 NPs and the Ar/NH 3 -FCNHGS. Moreover, when the Pt 1 Ni 2 @Ar/NH 3 -FCNHGS is used as cathode catalyst for direct methanol fuel cell, it exhibits superior open-circuit voltage (OCV = 730 mV) and similar peak power density (PPD = 62.8 mW cm−2) to 20 wt% Pt/C from 25 to 80 °C. More importantly, it showed better stability compared with 20 wt% Pt/C after about 72 h of stability testing. [Display omitted] • The well-dispersed Pt 1 Ni 2 NPs on FCNHGS was achieved by plasma with different atmospheres. • The plasma with different atmospheres produced different defect levels on FCNHGS. • The NPs size is related to the strength of the interaction between the substrate and the alloy NPs. • The OES deduce the formation of defects/functional groups on substrate materials. • The Pt 1 Ni 2 @Ar/NH 3 -FCNHGS is demonstrated to be a stable and efficient catalyst for ORR/HER. [ABSTRACT FROM AUTHOR]

Noble metal Pt is the acknowledged efficient catalyst for oxygen reduction (ORR) and hydrogen evolution reaction (HER) in commercial applications. However, due to its high price and limited reserves, its large-scale application is limited. In order to overcome this defect, the loaded Pt nanoparticles (NPs) should be small and dispersed efficiently through the design of electrode materials, so as to improve the utilization efficiency of Pt. In addition, the introduction of non-noble metal active sites can reduce the consumption of Pt efficiently. In this work, hollow graphene spheres are used as the carrier and the heteroatoms (N, Fe and Co) are introduced. The results show that the introduction of Fe and Co can form very effective heteroatom active sites (carbon encapsulated Fe/Co metals and FeCo alloy, and/or metal nitrides Fe/Co-N x -C) in the substrate material, which improve the catalytic activity of the electrode material effectively and the utilization efficiency of Pt. In addition, the generation of Fe/Co-N x -C active sites and the loading of Pt are also closely related to the doped N atoms. The onset potential, limiting current density (J L), half-wave potential (E 1/2) and Tafel slope of sample FeCo-N x HGSs/Pt (10 wt%) can exceed or comparable to those of commercial catalysts Pt/C (20 wt%) towards ORR both in acid and alkaline electrolyte. Moreover, the values of η 100 and the Tafel slope for FeCo-N x HGSs/Pt towards HER can also exceed the commercial catalysts Pt/C (20 wt%) in acid and alkaline electrolytes. The purpose of reducing the usage amount of precious metals without reducing the catalytic performance is realized. The relationship between the ORR and HER performance of the resultant electrode catalyst and the doped heteroatoms, such as nitrogen (N), iron (Fe) and cobalt (Co) atoms, was studied and discussed in detail. [Display omitted] • Pyridine and pyrrole N are easy to the formation of metal nitrides (Fe(Co)-N x -C). • Pyridine N is closely related to the rivet of precious metal Pt. • The Fe/Co in HGSs exist in the form of Fe/Co metals, FeCo alloy, Fe/Co-N x -C. • The Fe/Co atoms play a positive role in improving the ORR and HER performance. • The FeCo-N x HGSs/Pt is a stable and efficient catalyst for ORR/HER. [ABSTRACT FROM AUTHOR]

• Double-shelled hierarchical hollow NC@MoSe 2 nanobox has been synthesized for HER. • The NC@MoSe 2 with the optimum shell thickness shows the best HER activity. • The excellent HER activity is beneficial from the abundant exposed active edges. • It is also attributed to strong electronic coupling between MoSe 2 and NC layer. • DFT calculation results reveal the strong synergistic effect between NC and MoSe 2. Large-scale production of H 2 through water electrolysis is limited by the lack of efficient and crust-abundant low-cost electrocatalysts. Here, MoSe 2 and N-doped carbon (NC) is successfully constructed into a double-shelled hierarchical hollow nanobox. The obtained NC@MoSe 2 is demonstrated to be an active catalyst for hydrogen evolution reaction (HER). The NC@MoSe 2 delicately combine the structural and functional advantages of two-dimensional layered transition metal dichalcogenides (TMDs) and NC, which yield the striking synergistic effect to endow them with extremely enhanced electrochemical activity to efficiently catalyze the evolution of H 2. Remarkably, the NC@MoSe 2 with the optimum thickness of MoSe 2 shell can exhibit a fairly low onset potential of 61 mV, an extremely small overpotential of 164 mV vs. RHE at 10 mA cm−2, a greatly reduced Tafel slope of 55 mV dec−1, and a higher exchange current density of 0.102 mA cm−2. Specifically, this is mainly beneficial from the abundant exposed active edges from the edge-terminated ultrathin MoSe 2 nanosheets with small size, the overall hierarchical hollow architecture and strong electronic coupling between MoSe 2 and NC layer. Density functional theory (DFT) calculation results have well supported the experimental observations, revealing the strong synergistic effect between NC and MoSe 2 , thus the increased carrier density around the Fermi level and reduced hydrogen adsorption free energy (ΔG H*) for MoSe 2 composited with NC. [ABSTRACT FROM AUTHOR]

The Co 2 P-Ni 2 P/NF is demonstrated to be an efficient catalyst for HER and OER. Post-analysis shows the structure changes of the Co 2 P-Ni 2 P/NF during the initial periods of both HER and OER. • The Co 2 P-Ni 2 P/NF is synthesized by in situ growth of Co 2 P-Ni 2 P on the nickel foam. • It shows superhigh and stable catalytic activities for both the HER and the OER. • The structural evolutions of the Co 2 P-Ni 2 P/NF are systematically investigated. • It shows excellent performance for overall water splitting. Understanding of the structure changes of the catalysts during hydrogen (HER) and oxygen (OER) evolution reactions is of paramount importance for design of catalysts with enhanced performance. This work reports the structure change investigations of phosphide-based catalysts in both HER and OER. Specifically, nickel foam supported Co 2 P-Ni 2 P (Co 2 P-Ni 2 P/NF) is synthesized by in-situ growth of Co 2 P-Ni 2 P on the current collector, i.e. nickel foam, and then used for the investigation of the structure changes during HER and OER. This method avoids the use of polymer binders, allowing for the systematic analysis of the structure changes of the catalysts after HER and OER. The obtained Co 2 P-Ni 2 P/NF shows an excellent catalytic bifunctionality for HER and OER in alkaline solutions. It only needs an overpotential of 90 mV vs RHE to offer a current density of 10 mA cm−2 for HER and needs an overpotential of 230 mV vs RHE to offer a current density of 50 mA cm−2 for OER. Both HER and OER activities of Co 2 P-Ni 2 P/NF are higher than those of most bifunctional catalysts reported. Post-analysis shows the occurrence of the surface roughening and the formation of M P O (M Co and Ni) at the surface in its initial period of the HER, and the surface roughening and the formation of a thin layer of amorphous MOOH (M Co and Ni) at the surface in its initial period of OER. The surface roughening and formation of M P O and amorphous hydroxide layer can be attributed to the main reason responsible for its high performance for HER and OER. Additionally, the Co 2 P-Ni 2 P/NF is also usable as both the cathode and anode for an electrolyzer for overall water splitting and shows high performance. [ABSTRACT FROM AUTHOR]

A metal-free highly torn amine functionalized nitrogen doped graphene (HT-AFNG) used as hydrogen evolution reaction (HER) catalyst is prepared by using a simple synthesis method involving the hydrothermal reaction of graphene oxide in the presence of ammonia and the subsequent ball milling. The metal-free HT-AFNG is efficient for the HER in the acid solution and can deliver an onset potential of 100 mV and an overpotential of 350 mV at the current density of 10 mA cm −2 , which is much lower than those of the singly and dually doped graphene reported previously. The amine functionalized and nitrogen doped structure plays an important role in the high catalytic activity of the HT-AFNG, where the amine group can greatly reduce the |ΔG H* | value at both defect and edge sites as well as increases the electron transfer capability of nitrogen dope graphene (NG). Significantly, the highly torn structure also makes a big contribution on the high catalytic activity of the HT-AFNG, since it allows for the good accessibility of the active sites for the HER. The strategy involves the introduction of electron donating groups open a new research pathway towards the improvement of HER catalytic activity of graphene-based materials. [ABSTRACT FROM AUTHOR]

It is of great significance to improve the performance of electrocatalysts by constructing suitable heterogeneous interfaces to adjust the electronic structure of their surfaces. Here, we design and synthesize Co-Fe alloy nanoparticles (NPs) modified nitrogen-doped cubic carbon box (NC) supported MoS 2 nanosheets (NC@MoS 2 @Co-Fe) as a bi-functional electrocatalytic electrode material, which possesses excellent electrocatalytic oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) performance. The NC@MoS 2 @Co-Fe exhibits remarkable bifunctional electrocatalytic activities with an ORR half-wave potential of 0.73 V in 0.1 M KOH electrolyte and an OER overpotential of 400 mV, driving a current density of 10 mA cm−2. The advanced catalytic performance can be attributed to the unique heterojunction structure of the catalyst. The size of the Co-Fe alloy NPs supported on MoS 2 can be tuned to avoid the excessive growth of alloy NPs and to expose more catalytic active sites. Meanwhile, the loaded Co-Fe alloy NPs should be covered with a calcined carbon layer derived from the organic ligand to prevent oxidation passivation and particle aggregation. The structure formed by Co-Fe alloy NPs and NC@MoS 2 optimizes the electronic structure of the active center and accelerates the electrocatalytic reaction rate, thus synergistically improving the bi-functional electrocatalytic activity of the NC@MoS 2 @Co-Fe catalyst and can be applied to rechargeable zinc air batteries. Co-Fe alloy nanoparticles (NPs) modified nitrogen-doped cubic carbon box (NC) supported MoS 2 nanosheets (NC@MoS 2 @Co-Fe) is synthesized as a bi-functional electrocatalytic electrode material, which possesses excellent electrocatalytic oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) performance. [Display omitted] • The NC@MoS 2 @Co-Fe exhibits remarkable bi-functional electrocatalytic activities. • The assembled Zn-air batterie delivers a high power density and superior cycling performance. • The precise control of Co-Fe alloy on the surface electronic structure is realized. • The hollow nitrogen doped carbon box has a good electrolyte diffusion channel. • The unique MoS 2 @Co-Fe heterojunction structure optimizes the electronic structure of the active center. [ABSTRACT FROM AUTHOR]

• Plasma-assisted phosphorization could construct Ni 12 P 5 /ZnP 2 heterojunction. • The P-Ni/MoS 2 @Ni 12 P 5 /ZnP 2 is an excellent bifunctional catalyst. • It needs an overpotential of 82 mV vs. RHE to offer 10 mA cm−2 for HER. • It needs an overpotential of 360 mV vs. RHE to offer 100 mA cm−2 for OER. • The P-Ni/MoS 2 @Ni 12 P 5 /ZnP 2 (+, −) alkaline elctrolyzer showed superior performance. Plasma assisted phosphorization is employed to obtain homogeneous nickel phosphide and zinc phosphide nanoparticles (NPs) distributed over the surface of MoS 2 nanosheets. It exhibits admirable bifunctional catalysis activity towards water electrolysis. [Display omitted] Herein, Zn single atom supported MoS 2 nanosheets growing on nickel foam (NF) is formed by in-situ growth of MoS 2 nanosheets and ZIF-8 and high temperature carbonization. And then plasma-assisted-phosphorization is employed to obtain homogeneous nickel phosphide (Ni 12 P 5) and zinc phosphide (ZnP 2) heterojunction nanoparticles (NPs) distributed over the surface of MoS 2 nanosheets (P-Ni/MoS 2 @Ni 12 P 5 /ZnP 2). The MoS 2 nanosheets growing on 3D NF framework benefits the increase of the electrochemically active specific surface, and the uniform distribution of heterojunction Ni 12 P 5 /ZnP 2 NPs exposes more catalytic active sites. Moreover, the heterojunction Ni 12 P 5 /ZnP 2 NPs obtained by plasma-assisted-phosphorization has smaller size and stronger electronic coupling than that synthesized by the conventional thermal phosphorization (C-Ni/MoS 2 @Ni 12 P 5 /ZnP 2). Therefore, the as-synthesized P-Ni/MoS 2 @Ni 12 P 5 /ZnP 2 shows an excellent bifunctionality catalytic activity for both HER and OER in alkaline solutions, which is highlighted by the overpotential at 82 mV for delivering current density of 10 mA cm−2 for HER and 360 mV for delivering 100 mA cm−2 for OER. P-Ni/MoS 2 @Ni 12 P 5 /ZnP 2 exhibits higher electrocatalytic performance and better stability than most previously reported bifunctional catalysts. Furthermore, the catalytic current density of P-Ni/MoS 2 @Ni 12 P 5 /ZnP 2 as a bifunctional catalyst assembled single two-electrode-electrolyzer rapidly exceeded 50 mA cm−2 at a low cell voltage of 1.62 V, surpassing the commercial RuO 2 -Pt/C coupled electrolyzer. [ABSTRACT FROM AUTHOR]

• The spherical hollow graphene doped with different nitrogen structures are prepared. • The structures of doped N effect on the growth, shape, crystal structure of MoS 2+x. • PS is helpful for the uniform growth of MoS 2+x and the exposure of active sites. • The MoS 2+x composed of crystalline and amorphous states. • MoS 2+x supported on NH 2 -NHGSs exhibits the best HER activity. [Display omitted] MoS 2 , a two-dimensional (2D) layered structural transition metal dichalcogenide (TMDs), has been widely investigated towards hydrogen evolution reaction (HER) in previous few years. Except for the inert basal plane sites of the MoS 2 itself, its inherent low conductivity also hinders the electron transfer process, which adversely affects its efficiency towards HER. Therefore, how to expose more edge active sites and at the same time improve the conductivity of MoS 2 , either intrinsically or with the help of high conductive substrates, is a key means to improve the HER performance of MoS 2. Herein, the polystyrene (PS) nanospheres are used not only as an intercalation agent of graphene carbon sheets, but also as a spherical template for the preparation of 3D spherical hollow graphene. Different nitrogen precursors and nitrogen doping methods are used to prepare the 3D spherical hollow graphene substrate materials with different nitrogen-doping structures, such as amine N, pyrrolic N, pyridinic N or quaternary N. The investigation results show that the structure of doped nitrogen atom has a great influence on the loading of molybdenum disulfide. Among them, amine N was the most favorable for the loading of molybdenum disulfide, followed by pyrrole N, quaternary N and pyridine N. Moreover, the structure of doped N active sites synthesized by different preparation methods can also affect the uniform distribution of molybdenum disulfide on 3D spherical hollow graphene and the corresponding HER performance. The results show that, using ammonia as nitrogen source and PS microspheres as template, the prepared molybdenum disulfide loaded 3D spherical hollow graphene electrode material has the best HER performance, which should be attributed to the uniform distribution of the molybdenum disulfide and its close combination with the substrate, as well as the 3D spherical hollow structure. Moreover, the amorphous structure of molybdenum disulfide formed in the hydrothermal process can also improve the activity of HER. [ABSTRACT FROM AUTHOR]