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Developing efficient, low-cost and bifunctional catalysts with predominant durability for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is an extraordinary challenge in the preparation of green hydrogen energy by electrochemical water splitting. Three-dimensional (3D) transition metal compounds have become a research hotspot as OER electrocatalysts, which can replace noble metal oxides such as RuO 2 and IrO 2 to reduce application costs. Herein, we synthesized a novel three-dimensional pine-tree-like bimetallic sulfide arrays on nickel foam (FeCoS/NF) using various optimization strategies such as morphology optimization, in situ growth and introduction of heterogeneous structures. The as-synthesized FeCoS/NF electrocatalyst only requires relatively low overpotential of 156 mV to achieve a current density of 20 mA cm−2 for OER, with a Tafel slope of only 37 mV dec−1. It also has a small charge transfer resistance, an electrochemical surface area and good electrochemical stability in alkaline electrolytes. The excellent performance of FeCoS/NF can be attributed to the synergistic effect and amorphous phase of FeCoS as well as the well-defined pine-tree-like array architecture with a large surface area, abundant active sites, and sufficient gas and electrolyte diffusion channels. [Display omitted] • A 3D pine-tree-like structure of FeCoS/NF electrocatalyst was synthesized. • The FeCoS/NF exhibits excellent electrocatalytic activity for OER. • FeCoS/NF-based zinc-air battery shows an open-circuit voltage of 1.27 V. [ABSTRACT FROM AUTHOR]

The design of low-cost, short time, mass preparation and high-efficiency of electrocatalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and zinc air batteries are highly challenging. Herein, we design a bifunctional chrysanthemum-like electrocatalysts (Cu(OH) 2 @CoMoO 4 ·0.9H 2 O/CF) for highly efficient electrochemical water splitting by a simple and highly controllable two-step method in a few hours. This unique hierarchical electrocatalyst has porous structure and short diffusion paths, which can promote charge transfer, ion and water diffusion, and rapidly release hydrogen and oxygen bubbles. The obtained Cu(OH) 2 @CoMoO 4 ·0.9H 2 O/CF composite exhibits low overpotentials of 57 mV at −10 mA cm−2 toward the HER, which is superior to most of the previously reported CoMoO 4 -based electrocatalysts. And the Cu(OH) 2 @CoMoO 4 ·0.9H 2 O/CF exhibits excellent performance of 355 mV at 100 mA cm−2 toward the OER. Benefiting from the unique hierarchical heterostructure and the coupling effect between the inner and outer layers, the Cu(OH) 2 @CoMoO 4 ·0.9H 2 O/CF catalysts were endowed with high activity for water splitting. [Display omitted] [ABSTRACT FROM AUTHOR]

Developing a high-efficiency, stable and inexpensive bifunctional electrocatalyst/photocatalyst for hydrogen evolution reaction (HER) with suitable Gibbs free energy of hydrogen and rich electron transport channels remains a significant challenge. Herein, noble-metal-free Co nanoparticles decorated CePO 4 nanowires Co/CePO 4 were synthesized using Co-BTC/CePO 4 as a precursor via hydrothermal and calcination methods. A robust coupling heterostructure interface can be generated through carefully designed routes between Co nanoparticles and CePO 4 nanowires. In the HER process, the heterostructure interface can promote the composite catalysts conductivity, increase the active sites, charge-transfer efficiency, and adjust the desorption energy of hydrogen, thus enhancing their HER activity. Benefited from its specific structure, the obtained Co/0.1CePO 4 catalyst exhibits splendid electrocatalytic HER performance with an overpotential of only − 108 mV at − 10 mA cm−2 and a low Tafel slope of 85 mV decade−1, which is superior to many reported noble-metal-free catalysts. Especially, Co/0.1CePO 4 catalysts show an overpotential close to commercial 20 wt % Pt/C (−377 mV vs −340 mV) at a high current density of − 200 mA cm−2. Co/0.1CePO 4 catalyst also exhibits excellent photocatalytic hydrogen production rate (~87.5 μmol h−1) when working with organic photosensitizer Eosin Y. Furthermore, the Co/0.1CePO 4 catalyst reveals favorable stability in both electrocatalytic and photocatalytic HER. This research provides a new insight for fabricate efficient and stable composite HER catalysts. [Display omitted] • Composite of CePO 4 with Co as electro/photo-catalytic HER catalyst is reported. • Co/0.1CePO 4 exhibits excellent electrocatalytic HER performance with the overpotential of − 377 mV close to Pt/C (−340 mV) at high current density 200 mA cm−2. • Co/0.1CePO 4 shows superb photocatalytic HER performance with H 2 generation rate of 87.5 μmol h−1 when sensitized with Eosin-Y. • Mechanism of electro/photo-catalytic HER over Co/CePO 4 catalyst is proposed. [ABSTRACT FROM AUTHOR]

Few-layer and 1T-rich MoS2 is synthesized by a one-step solvothermal process using a rigid segment-containing polysulfide as a concomitant sulfur source and in situ intercalator. The prepared MoS2 displays superior hydrogen evolution reaction activity, providing a facile and mild approach for the development of high performing MoS2 and other two-dimensional lamellar materials. [ABSTRACT FROM AUTHOR]

The development of highly efficient, economical, and sustainable electrocatalysts based on non‐noble metals for hydrogen evolution reaction (HER) is of vital significance for large‐scale renewable energy storage. Herein, an effective synthetic strategy for the construction of MoO2 nanoflowers decorated with metallic Cu/Cu2O nanoparticles (NPs) on Ni foam (NF) (Cu2O/MoO2@Cu/NF) with a simple two‐step method is reported. The prepared Cu2O/MoO2@Cu/NF as an electrocatalyst exhibits outstanding reactivity and remarkable stability in alkaline solution. The onset overpotential of Cu2O/MoO2@Cu/NF approaches 0 V. An overpotential as low as 32 mV is obtained to afford a current density of 10 mA cm−2, comparable with Pt/C catalysts. The Tafel slope is low at 40 mV dec−1 as well. The involvement of zero‐valent Cu greatly reduces the resistance. The well‐dispersed Cu/Cu2O NPs on the sphere‐like MoO2 nanoflowers exaggerate the surface area. The ringent channels provide the fast release of evolved bubbles. Furthermore, the enhanced conductivity and large surface area lead to significant activity in HER. Herein, a novel design and facile synthesis of a highly efficient electrocatalyst with catalytic activity that is comparable to a Pt/C catalyst is provided. [ABSTRACT FROM AUTHOR]

In order to develop efficient and earth-abundant catalysts for large-scale hydrogen evolution via water splitting, a Ni/Ni(OH)2 dual composition electrocatalyst was manufactured via a two-step electrodeposition procedure. The stepwise fabricated 3D hierarchical nanoarrays as well as the concurrent dual composition electrodeposition yielded a papillae-like hybrid crystal structure. The high electrochemically active surface area, defect-rich hybrid crystal structure, and synergistic effects of the dual composition provided an elevated catalytic performance. Only 53 mV overpotential was needed to deliver a current density of 10 mA cm−2 with a small Tafel slope of 54.5 mV dec−1 to catalyze the HER in alkaline media. Approximately 81% catalytic activity could be maintained after 20 h of continuous testing, demonstrating long-term stability. Our findings offer an efficient approach to design and fabricate efficient noble-metal-free alkaline HER electrocatalysts. [ABSTRACT FROM AUTHOR]

The fabrication of non‐noble element electrocatalysts with comparable catalytic activity with Pt‐based materials is in great requirements for water splitting to achieve sustainable hydrogen production. Cu2S/MoS2 heterojunction nanorod arrays on copper foam were prepared for this purpose. The nitrogen doping was achieved in situ. HRTEM, SEM, XPS and EDX verified the heterojunction interfacial texture and the defect‐rich nanoarray configuration. The heterojunction interfacial texture, the defect rich configuration and the outward active sites optimized the structure required as a high‐efficient hydrogen evolution reaction (HER) electrocatalyst. As a result, the charge transfer resistance of the nanoarrays was estimated to be 5.4 Ω at −200 mV versus RHE, even lower than both the precursors. The electrochemical double layer capacitance was 49.95 mF cm−2, which was higher than both the precursors. The Cu2S/MoS2 heterojunction nanoarrays‐like electrocatalyst exhibited significant performance with a low overpotential (91 mV at 10 mA cm−2) and a small Tafel slope (41 mV dec−1) in alkaline electrolyte with 85.3 % retained ability after 1000 cycle runs. This work paves a road for developing high‐performance HER electrocatalysts. His and HER: Nitrogen doped Cu2S/MoS2 heterojunction nanorod arrays grafted on copper foam in situ have been created for efficient hydrogen evolution reaction. The results showed the remarkably improved catalytic activity by designing and tuning the heterostructure, conductivity and active sites. [ABSTRACT FROM AUTHOR]

• Composite of CePO 4 with Ni as a HER catalyst is reported. • CePO 4 lead to enhanced electrical conductivity and H 2 desorption ability. • Ni/CePO 4 shows excellent electrocatalytic HER performance at high current density. • Mechanism of photocatalytic HER over CePO 4 -Ni with Eosin Y photosensitizer and electrocatalytic HER are proposed. Developing suitable electrocatalyst/photocatalyst cocatalyst with electron transfer and desorption of hydrogen active sites is extremely significance for hydrogen evolution reaction (HER). Herein, we develop a series of Ni/(m)CePO 4 catalyst with rich interfaces via thermal treatment at low temperature with Ni-BTC/CePO 4 as precursor. The as-synthesized Ni/(m)CePO 4 heterojunction possess compact heterogeneous interface, and large specific surface area by loading Ni nanosphere on CePO 4 nanowire. By carefully designing method, the powerfully intimated heterointerface between Ni and CePO 4 conducive to the conversion of adsorption energy toward H atoms and electron conductivity, which enhance the synergic effect for electro-/photo-catalytic HER performances. Impressively, the Ni/0.1CePO 4 catalyst renders outstanding electrocatalytic HER activity with an lowest overpotential of −120 mV at −10 mA cm−2 and a optimal Tafel slope of 72 mV dec−1. The overpotential of Ni/0.1CePO 4 catalyst is −288 mV at −100 mA cm−2, close to 20 wt% Pt/C. With Eosin Y as photosensitizer, the photocatalytic performance for H 2 generation speed is around 64 umol h−1. Additionally, the Ni/0.1CePO 4 catalyst exhibits wonderful cycle stability in both electro-/photo-catalytic HER. The possible speculation of mechanisms of HER have also been proposed. This work provides a new insight into design HER catalysts for electro-/photo-catalytic hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

Developing high-performance nonprecious-metal electrocatalysts for the oxygen evolution reaction (OER) is crucial for efficient water splitting. Therefore, the reasonable design principle of catalyst, leading to high activity catalytic center and improving the accessibility of active sites, is undoubtedly crucial. Here, we used a kind of Prussian blue analogue (CoFe-PBA) nanoparticles to anchor the nitrogen-carbon doped CoFe 2 O 4 (CoFe 2 O 4 @NC) species to reduced graphene oxide aerogels as OER catalysts. The strong interaction between nanosized CoFe 2 O 4 @NC and the graphitic carbon shell led to synergistic effects in the OER, and the protection of the carbon shell guaranteed stability of the catalyst. As a result, the aerogel electrocatalyst exhibits more excellent activity and stability than the most advanced RuO 2 catalyst in OER under the same mass load in alkaline medium. It shows smaller overpotential of 250 mV to afford a current density of 10 mA cm−2 in a continuous working time of more than 70 hours. [Display omitted] • The catalyst has highly exposed active surface, multi-dimensional mass transfer pathway and good charge transfer ability. • The in-situ formation of nitrogen-carbon doped structure can greatly improve the catalytic activity and stability. • The binary active sites on the conductive GA network reduce the interfacial resistance and enhance catalytic activity. • The "Plum Pudding Model" structure integrates multiple requirements for catalyst design strategies. [ABSTRACT FROM AUTHOR]

Low-cost and earth-rich electrocatalysts with excellent catalytic activity in the electrochemical hydrogen evolution reaction (HER) are essential for large-scale renewable energy storage. Herein, we report a new type of core-shell Ni 2 P@CoP nanoarrays supported on nickel foam (NF) (Ni 2 P@CoP/NF) with large specific surface area, serving as an efficient cathode for hydrogen evolution reaction (HER). Plenty of tiny Ni 2 P nanosheets were tightly wrapped on the CoP nanowires, forming a rich heterostructure interface, which can provide more active sites and improve conductivity, thereby increasing their catalytic performance. What's more, the synergistic effect between Ni 2 P and CoP can promote the rapid electron transfer and improve the catalytic efficiency. The obtained Ni 2 P@CoP/NF NAs exhibited excellent HER activity with a low overpotential of 61 mV at 10 mA cm−2 and good durability in the alkaline media. The core-shell nanoarray structure of Ni 2 P@CoP/NF provides a novel method for the preparation of other heterojunction metal phosphides, which can be used to develop high performance HER electrocatalysts. [Display omitted] • Designed a new type of core-shell Ni 2 P@CoP nanoarrays supported on nickel foam. • The catalyst has a large specific surface area and rich heterostructure interfaces, which can provide more active sites. • The synergistic effect between Ni 2 P and CoP can promote the rapid electron transfer. • The obtained catalyst exhibits remarkable enhanced HER activities compared to pure Ni 2 P and CoP nanostructures. [ABSTRACT FROM AUTHOR]

Designing ultrahigh energy density and mass-loading of electrocatalysts for hydrogen evolution is highly desirable but remains a great challenge. Herein, a 3D high-rise architectural structure consisting of dense Ni(OH) 2 nanoparticles on CuMoO 4 nanocube heterostructure arrays on Ni foam (Ni(OH) 2 /CuMoO 4 /NF) is developed via a hydrothermal reaction, calcination and electrodeposition method. Benefitting from the optimized electronic configuration, hierarchical high-rise architecture, and large specific surface area and mesoporous, the Ni(OH) 2 /CuMoO 4 /NF exhibits superior hydrogen evolution reaction (HER) activity in 1.0 M KOH solution. Ni(OH) 2 /CuMoO 4 /NF only requires low overpotential of 70 mV achieving a current density of 10 mA cm−2 with a low Tafel slope of 80 mV dec−1, and superior long-term stability toward HER. This work provides a new structural design to high-rise architectural structures for efficient catalytic application. [Display omitted] • A highly topological nickel hydroxide doped copper molybdate oxide composite was synthesized. • The high-topology structure with a heterogeneous interface enhances the conductivity. • The typical structure and proper components contribute to the electrochemical activity. [ABSTRACT FROM AUTHOR]

Developing earth-abundant, low-cost, high-efficiency electrocatalysts for hydrogen evolution reaction (HER) by structure design is still a grand challenge. Herein, we fabricated Ni nanoparticles encapsulated by carbon loaded in two-dimensional carbon nanosheets (2D Ni@C@SU) using a molten salt (NaCl)-assisted pyrolysis method. Because of the large specific surface area (262.35 m²/g) and high electrical conductivity, the prepared 2D Ni@C@SU-0.75 electrocatalyst exhibits excellent HER electrocatalytic activity with the overpotential of −105 mV at −10 mA cm−2 and −367 mV at −200 mA cm−2, which is close to the commercial benchmark Pt/C (η 200 = −339 mV). Besides, the catalyst displays incredible durability in the electrocatalytic HER. This research indicates that the green solid-state synthetic strategy provides a new window for designing new Ni-based composite catalysts for electrocatalytic HER. [Display omitted] • Catalysts were prepared by a facile one-step synthesis. • The synthesis process is green and solvent-free. • Ni@C@SU-0.75 catalyzes hydrogen evolution reaction with -105 mV at 10 mA/cm2, and exhibited a good stability. • The 2D nanosheets encapsulated structure can increase the active sites and promote proton/electron transport. [ABSTRACT FROM AUTHOR]

The design and fabrication of stable, high-performance, and affordable oxygen evolution reaction (OER) electrocatalysts is essential for performing practical water electrolysis and generating green hydrogen energy. Here, we report that 2D few layer Ni 3 Fe nanosheets embedded with 2D porous nitrogen doped carbon (N-Ni x Fe@CF) from asphalt waste and then convolved and assembled into 1D hollow nanotube structures by Lewis acid molten salt etching method, which were used as electrocatalysts for OER. Benefiting from the integrate of 1D hollow nanotube structure and 2D porous nanosheets, the close contact between catalysts and support, and the increased conductivity, the resultant N-Ni 3 Fe@CF catalysts exhibited high catalytic activities in the OER with low overpotential at a current density of 10 mA cm−2 (114 mV), low Tafel slope (166.6 mV dec−1), and excellent electrochemical stability. This work provides a new concept for expanding the use of asphalt wastes and by-products, as well as a straightforward synthesis method for producing economical, efficient, and long-lasting alkaline OER electrocatalysts. • A 1D hollow nanotube shape N-Ni x Fe@CF was prepared by Lewis acid molten salt etching method. • The N-Ni x Fe@CF exhibits excellent electrocatalytic activity for oxygen evolution reaction. • It outperforms commercial noble metal-based catalyst of RuO 2 and most catalysts reported so far. • The outstanding OER activity is ascribed to the novel synthetic process and porous structure. [ABSTRACT FROM AUTHOR]

Due to the advantages of large specific surface area, high mass transfer efficiency and easy access to active sites, two dimensional (2D) nanomaterials provide a great opportunity for the construction of new versatile electrocatalysts with superior properties. Herein, a graphene-templated growth of MoS 2 -Ni 3 S 2 heterostructure with porous structure is successfully prepared on the Ni foam (MoS 2 /Ni 3 S 2 @G/NF) by one pot hydrothermal method. The electronic structure and surface properties of 2D chalcogenides are modified by heterogeneous interface and component engineering, so as to prepare a high-performance transition metal composite catalytic electrode for electrochemical reaction. The optimized MoS 2 /Ni 3 S 2 @G/NF shows excellent bifunctional activity and durability in alkaline medium. It only needs 53 mV and 265 mV overpotential to reach 10 mA cm−2 current density of HER and 20 mA cm−2 current density for OER, respectively. When the composite is used as an advanced electrocatalyst for water splitting, the 1.47 V voltage required to achieve a current density of 10 mA cm−2, which is better than the most non-noble metal electrocatalysts. The heterostructures between MoS 2 , Ni 3 S 2 and graphene are conducive to the synchronous chemical adsorption of hydrogen and oxygen-containing intermediates, which can improve the catalytic activity of overall water splitting. [Display omitted] • The synergy between MoS 2 nanosheets and Ni 3 S 2 particles enhances the intrinsic electrochemical activity of the material. • Graphene increases the load of active substances and regulates the interaction between electrons with faster carrier. • 3D nickel foam provides a binder free framework for catalytic reaction, greatly reducing charge transfer resistance. [ABSTRACT FROM AUTHOR]