Porous NiFe alloys synthesized via freeze casting as bifunctional electrocatalysts for oxygen and hydrogen evolution reaction

Binder-free NiFe-based electrocatalyst with aligned pore channels has been prepared by freeze casting and served as a bifunctional catalytic electrode for oxygen and hydrogen evolution reaction (OER and HER). The synergistic effects between Ni and Fe result in the high electrocatalytic performance of porous NiFe electrodes. In 1.0 M KOH, porous Ni₇Fe₃ attains 100 mA cm⁻² at an overpotential of 388 mV with a Tafel slope of 35.8 mV dec⁻¹ for OER, and porous Ni₉Fe₁ exhibits a low overpotential of 347 mV at 100 mA cm⁻² with a Tafel slope of 121.0 mV dec⁻¹ for HER. The Ni₉Fe₁//Ni₉Fe₁ requires a low cell voltage of 1.69 V to deliver 10 mA cm⁻² current density for overall water splitting. The excellent durability at a high current density of porous NiFe electrodes has been confirmed during OER, HER and overall water splitting. The fine electrocatalytic performances of the porous NiFe-based electrodes owing to the three-dimensionally well-connected scaffolds, aligned pore channels, and bimetallic synergy, offering excellent charge/ion transfer efficiency and sizeable active surface area. Freeze casting can be applied to design and synthesize various three-dimensionally porous non-precious metal-based electrocatalysts with controllable multiphase for energy conversion and storage.     

Fe2O3 nanoparticles immobilized on N and S codoped C as an efficient multifunctional catalyst for oxygen reduction reaction and overall water electrolysis

Currently, multifunctional electrocatalysts with superior performance are very vital for developing various clean and regenerated energy systems. Herein, an effective multifunctional electrocatalyst comprising Fe₂O₃ nanoparticles immobilized on N and S codoped C has been synthesized via heat-treatment of Fe(II) complex at 800 °C (denoted as Fe₂O₃/NS-C-800). Favorable features including the introduction of maghemite nanoparticles, N/S-codoping effect, and close contact between the Fe₂O₃ nanoparticles and NS-C ender the Fe₂O₃/NS-C-800 with high multifunctional catalytic performance. The onset potential (0.97 V) and half-wave potential (0.81 V) of the Fe₂O₃/NS-C-800 towards oxygen reduction reaction (ORR) are comparable to Pt/C (0.99 and 0.82 V). The Fe₂O₃/NS-C-800 also exhibits high oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity with low OER and HER overpotentials of 0.37 and −0.27 V at 10 mA cm⁻², respectively. In addition, higher ORR, OER and HER stabilities than Pt/C are observed for the Fe₂O₃/NS-C-800. More importantly, the assembled water electrolyzer using the Fe₂O₃/NS-C-800 as the anode and cathode exhibits a high stability at a water electrolysis current density of 10 mA cm⁻². The present study offers a new promising non-noble multifunctional catalyst for future application in renewable energy technologies.     

Impact in rational synthesis Co-ZIF templates for derived the structural Co@NC catalysis for high efficient hydrogen and oxygen evolution reactions

Developing highly active and stable non-noble metal bifunctional electrocatalysts are urgently demanded in overall water splitting. Herein, tunable precursor ratio synthesis of cobalt-based ZIFs as a template derived active cobalt embedded N-doped carbon (Co@NC) catalyst. The rational synthesis of ZIF templates significantly impacts the complex nanostructure and properties of the catalyst (Co@NC). Consequently, the different nanostructures on Co@NC exhibit significance for the electrocatalyst of hydrogen and oxygen evolution reactions. The optimized Co@NC-20 provides excellent electrocatalytic activity with the lowest overpotential of 172 and 301 mV for HER and OER, respectively, at the current density of 10 mA cm^?2. The bifunctional Co@NC-20 reveals a potential for overall water splitting as low as 1.68 V of 10 mA cm^?2. After continuously working for 24h, the exceptional stability activity maintains 75% of the catalytic performance on Co@NC-20. The beneficial character in the synergistic effects between high-active Co species with well-protection of the metal core by carbon shell promotes their excellent performance. This study provides an essential reference for the rational design of ZIF templates for electrocatalysts with more complex structures in the future.     

N,P-co-doped carbon coupled with CoP as superior electrocatalysts for hydrogen evolution reaction and overall water splitting

To achieve high activity and stability for both hydrogen and oxygen evolution reactions through the non-precious-metal based electrocatalysts is still facing the great challenge. Herein, we demonstrate a facile strategy to prepare CoP nanoparticles (NPs) loaded on N, P dual-doped carbon (NPC) electrocatalysts with high concentration N and P dopants through a pyrolysis-deposition-phosphidation process. The great bifunctional electrocatalytic activity for both HER (the overpotential of 98 mV and 86 mV at 10 mA cm⁻² in both 0.5 M H₂SO₄ and 1 M KOH electrolytes, respectively) and OER (the overpotential of 300 mV at 10  mA cm⁻² in 1 M KOH electrolyte) were achieved. When CoP@NPC hybrid was used as two electrodes in the 1 M KOH electrolyte system for overall water splitting, the needed cell potential for achieving the current density of 10 mA cm⁻² is 1.6 V, and it also showed superior stability for HER and OER after 10 h’ test with almost negligible decay. Experimental results revealed that the P atoms in CoP were the active sites for HER and the CoP@NPC hybrid showed excellent bifunctional electrocatalytic properties due to the synergistic effects between the high catalytic activity of CoP NPs and NPC, in which the doping of N and P in carbon led to a stronger polarization between Co and P in CoP, promoting the charge transfer from Co to P in CoP, enhancing the catalytic activity of P sites and Co sites in CoP for HER and OER, respectively. Specifically, the improvements could result from the changed charge state, the increased active specific surface area, and the facilitated reaction kinetics by N, P co-doping and admixture. This work provides a high-efficient, low-cost and stable electrocatalyst for overall water splitting, and throws light on rational designing high performance electrocatalysts.     

Cobalt phosphide nanoparticles embedded in 3D N-doped porous carbon for efficient hydrogen and oxygen evolution reactions

An electrocatalyst based on a unique three-dimensional (3D) N-doped porous carbon sheet networks embedded with CoP₂ nanoparticles (CoP₂@3D-NPC) was synthesized by a facile pyrolysis process as well as an in-situ phosphatization method. The improved CoP₂@3D-NPC hybrid materials show excellent electrocatalytic activity toward HER and OER. This material provides a low overpotential of 126 mV at 10 mA cm⁻² in 0.5 M H₂SO₄ and 167 mV at 20 mA cm⁻² in 1.0 M KOH for HER with a small Tafel slope value of 59 mV dec⁻¹, respectively. Besides, it is also active for the OER under alkaline conditions. Such a prominent property of the CoP₂@3D-NPC electrocatalyst could be attributed to its excellent electrical conductivity of 3D carbon substrate, strong synergistic effect between CoP₂ nanoparticles and carbon nanosheet as well as extra active sites created by the N-doped structure.     

Accelerated oxygen evolution kinetics on NiFeAl-layered double hydroxide electrocatalysts with defect sites prepared by electrodeposition

NiFe layered double hydroxides (LDHs) is considered to be one of the LDHs electrocatalyst materials with the best electrocatalytic oxygen evolution properties. However, its poor conductivity and inherently poor electrocatalytic activity are considered to be the limiting factors inhibiting the electrocatalytic properties for oxygen evolution reaction (OER). The amorphous NiFeAl-LDHs electrocatalysts were prepared by electrodeposition with nickel foam as the support, and the D-NiFeAl-LDHs electrocatalyst with defect sites was then obtained by alkali etching. The mechanism of catalysts with defect sites in OER was analyzed. The ingenious defects can selectively accelerate the adsorption of OH⁻, thus enhancing the electrochemical activity. The D-NiFeAl-LDHs electrocatalyst had higher OER electrocatalytic activity than NiFe-LDHs electrocatalyst: its accelerated OER kinetics were mainly due to the introduction of iron and nickel defects in NiFeAl-LDHs nanosheets, which effectively adjusted the surface electronic structure and improved OER electrocatalytic performance. There was only a low overpotential of 262 mV with the current density of 10 mA cm⁻², and the Tafel slope was as low as 41.67 mV dec⁻¹. The OER electrocatalytic performance of D-NiFeAl-LDHs was even better than those of most of the reported NiFe-LDHs electrocatalysts.     

Accessible active sites activated by nano cobalt antimony oxide @ carbon nanotube composite electrocatalyst for highly enhanced hydrogen evolution reaction

The electrochemical hydrogen evolution reaction (HER) was one of new energy development strategies with clean, efficient and renewable characteristics, and electrocatalysts play a crucial role in HER technology. Herein, a composite material (CSO@0.5CNT) derived from the combination of nano cobalt antimony oxide (CSO) with carbon nanotubes (CNT) through hydrothermal reaction, in which the nanoparticles of CSO were closely compounded on the surface of CNT, could be a highly efficient electrocatalyst for HER in 1 M KOH. The binary composite electrocatalyst of CSO and CNT reduced the internal resistance, promoted the charge transfer, exhibited a large electrochemical active area, and obtained the lower overpotential, with 155 mV at 10 mA/cm² current density. Moreover, such a CSO@0.5CNT electrocatalyst displayed a small Tafel slope of 86.5 mV dec^?1, excellent catalytic activity and extraordinary long-term structural stability after 30 h and 3000 CV cycles. Furthermore, the electrocatalytic mechanism revealed by Density Functional Theory (DFT) calculation proved that, the decomposition of H₂O molecules was the control step of the whole HER, and the superior electron transport ability of CNT was favorable to the improvement of electrocatalytic performance. Benefitting from accessible active sites on carbon nanotube (C atom) and CSO (Co atom), the composite electrocatalyst of CSO@0.5CNT displayed synergistic effect for electrocatalytic HER properties, and that was the main mechanism for significantly improving the electrocatalytic activities. Our work provides a novel strategy towards high-efficiency electrocatalysts for hydrogen evolution reaction.     

Novel 3-D urchin-like Ni– Co–W porous nanostructure as efficient bifunctional superhydrophilic electrocatalyst for both hydrogen and oxygen evolution reactions

Fabrication of an electrocatalyst with remarkable electrocatalytic activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is important for the production of hydrogen energy. In this study, Ni–Co–W alloy urchin-like nanostructures were fabricated by binder-free and cost-effective electrochemical deposition method at different applied current densities and HER and OER electrocatalytic activity was studied. The results of this study showed that the microstructure and morphology are strongly influenced by the electrochemical deposition parameters and the best electrocatalytic properties are obtained at the electrode created at the 20 mA.cm⁻²applied current density. The optimum electrode requires −66 mV and 264 mV, respectively, for OER and HER reactions for delivering the 10 mA cm⁻² current density. The optimum electrode also showed negligible potential change after 10 h electrolysis at 100 mA cm⁻², which means remarkable electrocatalytic stability. In addition, when this electrode used as a for full water splitting, it required only 1.58 V to create a current density of 10 mA cm⁻². Such excellent electrocatalytic activity and stability can be related to the high electrochemical active surface area, being binder-free, high intrinsic electrocatalytic activity and hydrophilicity. This study introduces a simple and cost-effective method for fabricating of effective electrodes with high electrocatalytic activity.     

First insight on Mo(II) as electrocatalytically active species for oxygen evolution reaction

The replacement of noble metals with earth-abundant metals is still a big challenge for the practical application of electrocatalysis. In this work, we have developed the Mo_xC-modified alloy@nitrogen-doped carbon hybrid electrocatalysts (Mo_xC-alloy@NC, alloy: FeCo, NiCo) for oxygen evolution reaction (OER) by a simple thermolysis method. Compared with FeCo@NC and NiCo@NC, the OER performances of Mo_xC-FeCo@NC and MoC-NiCo@NC are greatly enhanced, mainly due to the improved electrical conductivity by the introduce of Mo_xC. Moreover, Mo_xC-FeCo@NC exhibits a smaller Tafel slope (80 mV/dec) and a lower overpotential (318 mV) at 10 mA cm⁻² in 1 M KOH solution, compared with MoC-NiCo@NC (186 mV/dec, 352 mV). In consideration of a lower BET area (6.6 m² g⁻¹) of Mo_xC-FeCo@NC than those of MoC-NiCo@NC (25.4 m² g⁻²), the remarkable electrocatalytic activity of Mo_xC-FeCo@NC is mainly attributed to the presence of Mo(II) acting as the OER active species. Although Mo as hydrogen evolution reaction (HER) active species is well known, Mo(II) as the OER active species has not been reported before.     

Nickel foam-supported Fe,Ni-Polyporphyrin microparticles: Efficient bifunctional catalysts for overall water splitting in alkaline media

Developing highly active, stable and sustainable electrocatalysts for overall water splitting is of great importance to generate renewable H₂ for fuel cells. Herein, we report the synthesis of electrocatalytically active, nickel foam-supported, spherical core-shell Fe-poly(tetraphenylporphyrin)/Ni-poly(tetraphenylporphyrin) microparticles (FeTPP@NiTPP/NF). We also show that FeTPP@NiTPP/NF exhibits efficient bifunctional electrocatalytic properties toward both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Electrochemical tests in KOH solution (1 M) reveal that FeTPP@NiTPP/NF electrocatalyzes the OER with 100 mA cm⁻² at an overpotential of 302 mV and the HER with 10 mA cm⁻² at an overpotential of 170 mV. Notably also, its catalytic performance for OER is better than that of RuO₂, the benchmark OER catalyst. Although its catalytic activity for HER is slightly lower than that of Pt/C (the benchmark HER electrocatalyst), it shows greater stability than the latter during the reaction. The material also exhibits electrocatalytic activity for overall water splitting reaction at a current density of 10 mA cm⁻² with a cell voltage of 1.58 V, along with a good recovery property. Additionally, the work demonstrates a new synthetic strategy to an efficient, noble metal-free-coordinated covalent organic framework (COF)-based, bifunctional electrocatalyst for water splitting.     

Co-Ni based hybrid transition metal oxide nanostructures for cost-effective bi-functional electrocatalytic oxygen and hydrogen evolution reactions

Water splitting is widely regarded as one of the promising technologies for hydrogen fuel production and foreshadowed to assist in meeting the global energy demand as a sustainable and reliable energy technology. In this regard, we report on the facile chemical synthesis of hybrid Cobalt (Co) and Nickel (Ni) oxide nanostructure for low-cost bi-functional electrocatalytic water splitting applications. Their crystalline characteristics and chemical structure were studied using X-ray diffraction and Fourier-Transform infrared (FT-IR) spectrum. The nanostructure morphology was investigated by scanning and high-resolution transmission electron microscopy (SEM/HRTEM). The 2⁺ and 3⁺ valence state of Co and Ni metal ions was identified using X-ray photoelectron spectroscopy (XPS). The hybrid oxide electrocatalyst was found to display an excellent oxygen/hydrogen evolution reaction (OER/HER activity) in alkaline condition. The realization of random heterojunction configuration across the hybrid nanostructures was found to offer an improved conductivity and enhanced charge transfer capability to promote the gas evolution kinetics. Overpotential value of 203 and 378 mV was registered from the respective OER and HER polarization curves (for current density of ±10 mA cm⁻²). Tafel slope of 87 mV/dec for OER and 90 mV/dec for HER along with the long-term stability results authenticated the anodic/cathodic characteristics of hybrid oxides for overall water splitting applications.     

In-situ facile synthesis of heterostructural Co||MnCo2O4.5/NC with active oxygen vacancies and its bifunctional electrocatalysis for oxygen reduction and oxygen evolution reaction

A potential non-noble metal oxide catalyst with its low-cost and efficient catalytic ability attract increasing attention. In this paper, a highly efficient bifunctional electrocatalyst Co||MnCo₂O_4.5/NC with heterostructure and oxygen vacancies is prepared utilizing solid reaction in-situ. The optimal catalyst is obtained at 650 °C with the mass ratio (1:8) of MnCo₂O_4.5 and Dicyandiamide (DCD). It shows excellent electrocatalytic activity for oxygen reduction reaction (ORR) with high half-wave potential (0.81 V) and limit current density (6.22 mA cm^?2), which is better than that of the commercial 20% Pt/C(0.81 V, 5.52 mA cm^?2). At the same time, it also exhibits superior electrocatalytic activity for oxygen evolution reaction (OER) with low overpotential (330 mV) and a faster dynamics process. The superior electrocatalytic properties may be resulted from the presence of heterostructure and increasing ratio of oxygen vacancies, which helps to the rapid transfer of electrons and creates more active sites. Moreover, the self-generated N-doped carbon provides high conductivity of the as-prepared Co||MnCo₂O_4.5/NC composite. It can be seen that the application of interface engineering technologies is useful for improving the performance of the catalyst, providing an effective and facile synthesis strategy for non-noble metal catalyst.     

Tailoring Cr doped NiFeP nanoparticles embedded in 3D cellulose nanofibrils carbon architecture for efficient oxygen evolution reaction

Oxygen evolution reaction (OER) is considered the bottleneck that restricting the pace of electrocatalytic hydrogen production. Modulating structure and heterogeneous doping are essential approaches to effectively promote the electrocatalytic efficiency and stability. Herein, three-dimensional (3D) porous Cr doped NiFeP nanoparticles encapsulated in cellulose nanofibrils (CNF) carbon architecture (Cr–NiFeP/NC) with high-efficiency and durable OER performance was constructed. CNF played crucial role on the construction of 3D porous framework and promoting the OER performance significantly. Benefiting from the 3D porous structure, high specific surface area and exposed abundant active sites, the Cr–NiFeP/NC electrocatalyst displayed excellent OER performance, which the overpotential to deliver the current density of 10 mA cm⁻² was only 249 mV with a Tafel slope of 51.2 mV dec⁻¹ in 1.0 M KOH, outperforming the RuO₂ and other reported electrocatalysts remarkably. In addition, the Cr–NiFeP/NC electrocatalyst exhibited outstanding stability, which the overpotential was only increased by 2.5% after 48 h chronopotential measurement to deliver a current density of 10 mA cm⁻² with stable morphology and structure. This work demonstrated an integrated strategy of Cr doping and 3D porous structure modulating employed CNF as skeleton for the efficient and durable OER performance, providing a spark for hydrogen production by water splitting.     

Iron-substituted Co-Ni phosphides immobilized on Ni foam as efficient self-supported 3D hierarchical electrocatalysts for oxygen evolution reaction

Electrocatalytic water splitting for hydrogen evolution is significantly impeded by the kinetically sluggish oxygen evolution reaction (OER). Thus, the development of highly efficient and durably stable non-noble-metal OER electrocatalyst is necessary and challenging for the large-scale electrocatalytic water splitting. Herein, a series of iron-substituted cobalt-nickel phosphides grown on Ni foam (FeCoNi-P/NFs) were easily prepared though successive hydrothermal and phosphorization treatments. The chemical compositions, crystalline and electronic structures as well as surface morphologies of these resulting electrocatalysts are strongly related with the iron substitution ratio. More interestingly, the FeCoNi-P/NF-2 nanosheet arrays prepared from equivalent molar ratio of iron and cobalt precursors exhibit the best OER performance with a low overpotential of 266 mV to produce a current density of 50 mA cm⁻² and a low Tafel slope of 61.2 mV dec⁻¹ in 1.0 M KOH condition, which is comparable to the reported state-of-the-art OER electrocatalysts. Additionally, the FeCoNi-P/NF-2 nanosheet arrays also show satisfactory long-term durability over 60 h. The superior OER activity of the electrocatalyst is essentially attributed to the heteroatomic substitution and the unique three-dimensional hierarchical morphology, which greatly increase the electrical conductivity, afford more active sites and facilitate the efficient charge transfer ability.     

Construction of P,N-codoped carbon shell coated CoP nanoneedle array with enhanced OER performance for overall water splitting

Water electrolysis to generate hydrogen (H₂) and oxygen (O₂) was a sustainable alternative for clean energy in the future but remained challenging. Herein, we fabricated a nanoneedle-like CoP core coated by a P,N-codoped carbon shell (CoP@PNC@NF). The hierarchical structure, unique nanoneedle-like morphology, CoP core, and P,N-codoped carbon shell were responsible for the high electrocatalytic activity. Electrocatalytic tests demonstrated that CoP@PNC@NF displayed low overpotentials of 137.6 and 148.4 mV, as well as Tafel slopes of 59.89 and 56.40 mV dec⁻¹ for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, at 10 mA cm⁻² in 1.0 M KOH. The bifunctional electrocatalyst CoP@PNC@NF also exhibited a low cell voltage of 1.458 V to yield 10 mA cm⁻² in the two-electrode system and could maintain the activity for 50 h. The Faradaic efficiencies of CoP@PNC@NF for both HER and OER were nearly 100%. The result outperformed the precious-metal-based electrocatalyst apparatus (RuO₂||Pt/C) and other carbon-coated transition-metal phosphides (TMPs). This work paved the way for the rational design of carbon shell-coated TMPs with low energy barriers for converting and storing electrochemical energy.     

Iron-doped metal-organic framework with enhanced oxygen evolution reaction activity for overall water splitting

Water electrolysis is an energy conversion technology to provide green and clean hydrogen energy. Developing a high-efficient and durable electrocatalyst is a critical material for water electrolysis. Therefore, we synthesize a series of iron-doped metal-organic frameworks (MOFs) by a facile one-pot hydrothermal method. In the conventional three-electrode-cell, the Co/Fe (1:1)-MOF catalyst exhibits an overpotential of 317 mV at a current density of 10 mA cm⁻² in the oxygen evolution reaction (OER). Furthermore, the electrolysis performance of Co/Fe (1:1)-MOF catalyst is further evaluated in a home-made anion-exchange-membrane water electrolysis cell. With the Co/Fe (1:1)-MOF as the OER catalyst and commercial Pt/C as the hydrogen-evolution-reaction catalyst, the cell presents an overpotential of 490 mV at a large current density of 500 mA cm⁻², which is superior to the benchmark cell with commercial IrO₂ as the OER catalyst in the alkaline media. Theoretical calculation demonstrates that the introduction of Fe dopant into MOFs significantly reduces the binding energy of 1O and 1OOH intermedium during the OER progress. Consequently, the electrocatalytic activity is increased, which is perfectly consistent with the experimental results. This work suggests that the iron-doped MOFs structure significantly improves the electrocatalytic activity and provides a facile strategy to produce hydrogen at a large current density for industrial water electrolysis.     

Self-supported hierarchical porous FeNiCo-based amorphous alloys as high-efficiency bifunctional electrocatalysts toward overall water splitting

Rationally designing an efficient and cost-effective bifunctional electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is a primary matter in applying electrocatalytic water splitting. Herein, a self-supported FeNiCo-based amorphous catalyst with a hierarchical micro/nanoporous structure is fabricated by dealloying an amorphous/nanocrystalline precursor. The amorphous nanoporous framework enables the prepared electrocatalyst to afford fast reaction kinetics, abundant active sites, and enhanced electrochemical active surface areas (ECSAs). Such structural advantages and the synergistic effects of the ternary transition metals contribute to a dramatic catalytic activity of this electrocatalyst under alkaline conditions, which delivers the current density of 10 mA cm⁻² at a low overpotential of 134 mV for HER and 206 mV for OER, respectively. Furthermore, a full electrolysis apparatus constructed by the self-supported hierarchical micro/nanoporous FeNiCo-based amorphous electrocatalyst as both cathode and anode acquires a dramatically low voltage of 1.58 V operating at 10 mA cm⁻² along with stability for more than 24 h for overall water splitting.     

Template confined construction of Fe–NiCoP/NiCoP/NF heterostructures for highly efficient electrocatalytic oxygen evolution reaction

Rational design of oxygen evolution reaction (OER) electrocatalysts with advance nanostructures and composition superiority is an urgent need to promote electrocatalytic property. In this research, we fabricate Fe–NiCoP/NiCoP/NF electrocatalyst for OER via the interfacial scaffolding strategy with Prussian-blue-analogue (PBA) followed by low-temperature phosphating. The cube-on-sheet multimetallic-TMPs-based nanoarchitecture of Fe–NiCoP/NiCoP/NF exhibits outstanding OER performance, which only requires the overpotential of 201 mV to achieve a current density of 10 mA cm⁻² and possesses good durability up to 50 h in 1.0 M KOH solution. The superior OER property of Fe–NiCoP/NiCoP/NF is mainly characteristic to the rich composition that optimizes the electronic structure and the cube-on-sheet multimetallic-TMPs-based nanoarchitecture which can facilitate more effective active sites exposure and ultimately promote charge transfer at the same time. This research provides a new strategy for the construction of advanced nanoarrays structure and the improvement of the electrocatalytic performance of polymetallic phosphides, which offers its promising applications especially in energy storage and conversion technology.     

Bifunctional nanoporous ruthenium-nickel alloy nanowire electrocatalysts towards oxygen/hydrogen evolution reaction

A class of ruthenium-nickel alloy catalysts featured with nanoporous nanowires (NPNWs) were synthesized by a strategy combining rapid solidification with two-step dealloying. RuNi NPNWs exhibit excellent electrocatalytic activity and stability for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in which the RuNi-2500 NPNWs catalyst shows an OER overpotential of 327 mV to deliver a current density of 10 mA cm^?2 and the RuNi-0 NPNWs catalyst requires the overpotential of 69 mV at 10 mA cm^?2 showing the best HER activity in alkaline media. Moreover, the RuNi-1500 NPNWs catalyst was used as the bifunctional electrocatalyst in a two-electrode alkaline electrolyzer for water splitting, which exhibits a low cell voltage of 1.553 V and a long-term stability of 24 h at 10 mA cm^?2, demonstrating that the RuNi NPNWs catalysts can be considered as promising bifunctional alkaline electrocatalysts.