3D Carbon Foam Supported Edge-Rich N-Doped MoS2 Nanoflakes for Enhanced Electrocatalytic Hydrogen Evolution

Molybdenum disulfide (MoS₂) is one of the most promising alternatives to the Pt-based electrocatalysts for the hydrogen evolution reaction (HER). However, its performance is currently limited by insufficient active edge sites and poor electron transport. Hence, enormous efforts have been devoted to constructing more active edge sites and improving conductivity to obtain enhanced electrocatalytic performance. Herein, the 3D carbon foam (denoted as CF) supported edge-rich N-doped MoS₂ nanoflakes were successfully fabricated by using the commercially available polyurethane foam (PU) as the 3D substrate and PMo₁₂O₄₀³⁻ clusters (denoted as PMo₁₂) as the Mo source through redox polymerization, followed by sulfurization. Owing to the uniform distribution of nanoscale Mo sources and 3D carbon foam substrate, the as-prepared MoS₂-CF composite possessed well-exposed active edge sites and enhanced electrical conductivity. Systematic investigation demonstrated that the MoS₂-CF composite showed high HER performance with a low overpotential of 92 mV in 1.0 m KOH and 155 mV in 0.5 m H₂SO₄ at a current density of 10 mA cm⁻². This work offers a new pathway for the rational design of MoS₂-based HER electrocatalysts.     

Rational Design and Controlled Synthesis of V-Doped Ni3S2/NixPy Heterostructured Nanosheets for the Hydrogen Evolution Reaction

Rational construction of high-efficiency and low-cost catalysts is one of the most promising ways to produce hydrogen but remains a huge challenge. Herein, interface engineering and heteroatom doping were used to synthesize V-doped sulfide/phosphide heterostructures on nickel foam (V-Ni₃S₂/Ni_xP_y/NF) by phosphating treatment at low temperature. The incorporation of V can adjust the electronic structure of Ni₃S₂, expose more active sites, and protect the 3D structure of Ni foam from damage. Meanwhile, the heterogeneous interface formed between Ni₃S₂ and Ni_xP_y can provide abundant active sites and accelerate electron transfer. As a result, the V-Ni₃S₂/Ni_xP_y/NF nanosheet catalyst exhibits outstanding activity in the hydrogen evolution reaction (HER) with an extremely low overpotential of 90 mV at a current density of 10 mA cm⁻² and stable durability in alkaline solution, which exceeds those most of the previously reported Ni-based materials. This work shows that rational design by interfacial engineering and metal-atom incorporation has a significant influence for efficient hydrogen evolution.     

经由[Ni(en)3](SeO3)配合物电镀制备的硒化镍高效电催化水分解反应

电催化水分解是一种高效制备清洁氢气能源的有效方法. 开发高效、稳定、廉价、双功能的电催化剂用于水的氧化与还原反应一直以来都是具有挑战的课题. 在这篇论文中,作者报道了一种生长在碳布上高活性的硒化镍微球. 该催化剂通过对同时包含镍和硒元素的亚硒酸镍配合物进行电解制备. 由于前驱分子同时含有两种有效元素,制备得到的硒化镍具有很好的形貌和元素分步均一性. 制备得到的NiSe-EA/CC电极能够双功能催化水的氧化与还原. 在154 mV析氢过电势下能达到10 mA·cm^-2的催化电流. 同时,在250 mV析氧过电势下能达到20 mA·cm^-2电催化电流. 用该电极材料同时作为阴极和阳极制备的全电解水电解池能在1.53 V的电压下实现10 mA·cm^-2的稳定电解电流.     

Hierarchical Rhree-dimensional CoNi LDH-Ni3S2 Supported on Ni Foam as a Stable and Efficient Electrocatalytic Material for Overall Water Splitting

Herein, a novel self-supporting three-dimensional nanostructured CoNi LDH-Ni₃S₂ catalyst was generated in a two-step process combining hydrothermal synthesis and high-temperature electrodeposition techniques. The CoNi LDH-Ni₃S₂/NF electrode exhibits superior electrocatalytic performance with low overpotentials of 193 and 382 mV in 1 M KOH to drive a high current density of 100 mA cm⁻² for HER and OER, respectively. Meanwhile, a small cell voltage of 1.51 V was obtained upon using CoNi LDH-Ni₃S₂/NF as a dual-functional catalyst. Additionally, CoNi LDH-Ni₃S₂/NF exhibits high stability with almost no change in HER and OER overpotentials and electrocatalytic total decomposition of water within 80,000 s.     

介孔调控Co9S8/Ni3S2复合电极材料及电催化析氢性能

利用快速凝固结合化学脱铝模板法制备前驱体纳米多孔Ni-Co合金,再经气相沉积硫和热氢还原制备纳米多孔Co₉S₈/Ni₃S₂复合电极材料。研究表明,通过气相沉积,硫原子与Ni-Co合金原位生成CoS₂/NiS₂复合相,再经过热氢还原后,形成硫原子比例较低的Co₉S₈/Ni₃S₂复合相。该热氢还原过程不仅提高了Co₉S₈/Ni₃S₂各元素周围的电子密度,而且在其表面调制出有介孔结构的异质界面,进而提高其电子传输能力并增大活性比表面积。相比于其他同条件下制备的Ni、Co硫化物,Co₉S₈/Ni₃S₂拥有更佳的析氢反应（HER）活性,在50 mA·cm^-2的电流密度下,Co₉S₈/Ni₃S₂的HER过电位为234 mV,Tafel斜率为106 mV·dec^-1,经稳定性测试后,电压变化仅为14 mV。     

Hierarchical FeCo2S4@FeNi2S4 Core/Shell Nanostructures on Ni Foam for High-Performance Supercapacitors

The design of electrode materials with rational core/shell structures is promising for improving the electrochemical properties of supercapacitors. Hence, hierarchical FeCo₂S₄@FeNi₂S₄ core/shell nanostructures on Ni foam were fabricated by a simple hydrothermal method. Owing to their structure and synergistic effect, they deliver an excellent specific capacitance of 2393 F g⁻¹ at 1 A g⁻¹ and long cycle lifespan as positive electrode materials. An asymmetric supercapacitor device with FeCo₂S₄@FeNi₂S₄ as positive electrode and graphene as negative electrode exhibited a specific capacitance of 133.2 F g⁻¹ at 1 A g⁻¹ and a high energy density of 47.37 W h kg⁻¹ at a power density of 800 W kg⁻¹. Moreover, the device showed remarkable cycling stability with 87.0 % specific-capacitance retention after 5000 cycles at 2 A g⁻¹. These results demonstrate that the hierarchical FeCo₂S₄@FeNi₂S₄ core/shell structures have great potential in the field of electrochemical energy storage.     

包覆Y(OH)3的球形Ni(OH)2的电化学性能

利用软嵌式粉末电极技术研究了Y(OH)3包覆对球形Ni(OH)2电化学性能的影响. 循环伏安结果表明, 在球形Ni(OH)2的氧化过程中存在Ni(Ⅲ)和Ni(Ⅳ)的两步氧化反应, 产生的Ni(Ⅳ)不稳定, 能分解产生NiOOH和氧气, 所以可将Ni(Ⅲ)→Ni(Ⅳ)看作副反应. Y(OH)3包覆层对Ni(OH)2氧化过程后期的副反应, 特别是Ni(Ⅲ)→Ni(Ⅳ)具有较好的抑制作用. 由包覆后的Ni(OH)2制成的模拟电池表现出很好的高温性能, 在1C充放电条件下, 当Y的摩尔分数为1.61%时, 在60 ℃时所对应的容量保持率可达到25 ℃的92.7％; 当Y的摩尔分数仅为0.55 %时, 在60 ℃时所对应的质量比容量也可达到241.3 mA·h/g.     

Interface Engineering of MoS2/Ni3S2 Heterostructures for Highly Enhanced Electrochemical Overall‐Water‐Splitting Activity

To achieve sustainable production of H₂ fuel through water splitting, low‐cost electrocatalysts for the hydrogen‐evolution reaction (HER) and the oxygen‐evolution reaction (OER) are required to replace Pt and IrO₂ catalysts. Herein, for the first time, we present the interface engineering of novel MoS₂/Ni₃S₂ heterostructures, in which abundant interfaces are formed. For OER, such MoS₂/Ni₃S₂ heterostructures show an extremely low overpotential of ca. 218 mV at 10 mA cm^?2, which is superior to that of the state‐of‐the‐art OER electrocatalysts. Using MoS₂/Ni₃S₂ heterostructures as bifunctional electrocatalysts, an alkali electrolyzer delivers a current density of 10 mA cm^?2 at a very low cell voltage of ca. 1.56 V. In combination with DFT calculations, this study demonstrates that the constructed interfaces synergistically favor the chemisorption of hydrogen and oxygen‐containing intermediates, thus accelerating the overall electrochemical water splitting.     

First-Row Transition-Metal Cations (Co2+, Ni2+, Mn2+, Fe2+) and Graphene (Oxide) Composites: From Structural Properties to Electrochemical Applications

Composites of graphene (oxide) (GO) and first-row transition-metal cations (Co²⁺, Ni²⁺, Mn²⁺, Fe²⁺) are prepared by mixing GO and aqueous metal salt solutions. The amount of metal cation bound to GO nanosheets is calculated by using inductively coupled plasma mass spectrometry (ICP-MS) and the possible binding sites of the metals are investigated by means of attenuated total reflectance infrared (ATR-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. Electrodes loaded with the metal/GO composites are prepared by a simple drop-casting technique without any binders or conductive additives. The effect of electrochemical reduction on the structure of the composite electrodes is investigated by Raman spectroscopy, XPS, X-ray diffraction (XRD) analysis, and field emission scanning electron microscopy (FESEM). A detailed electrochemical characterization is performed for the utilization of the composite electrodes for electrochemical capacitors and possible oxygen reduction reaction electrocatalysts by cyclic voltammetry (CV) and rotating disk electrode measurements. The highest areal capacitance is achieved with the as-deposited Fe/GO composite (38.7 mF cm⁻² at 20 mV s⁻¹). In the cyclic stability measurements, rCo/GO, rNi/GO, rMn/GO, and rFe/GO exhibit a capacitance retention of 44, 1.1, 73, and 87 % after 3000 cycles of CV at 100 mV s⁻¹, respectively.     

Devisable POM/Ni Foam Composite: Precisely Control Synthesis toward Enhanced Hydrogen Evolution Reaction at High pH

Polyoxometalates (POMs) are promising catalysts for the electrochemical hydrogen production from water owing to their high intrinsic catalytic activity and chemical tunability. However, poor electrical conductivity and easy detachment of the POMs from the electrode cause significant challenges under operating condition. Herein, a simple one-step hydrothermal method is reported to synthesize a series of Dexter–Silverton POM/Ni foam composites (denoted as Ni M -POM/Ni; M =Co, Zn, Mn), in which the stable linkage between the POM catalysts and the Ni foam electrodes lead to high activity for the hydrogen evolution reaction (HER). Among them, the highest HER performance can be observed in the NiCo-POM/Ni, featuring an overpotential of 64 mV (at 10 mA cm⁻², vs. reversible hydrogen electrode), and a Tafel slope of 75 mV dec⁻¹ in 1.0 m aqueous KOH. Moreover, the NiCo-POM/Ni catalyst showed a high faradaic efficiency ≈97 % for HER. Post-catalytic of NiCo-POM/Ni analyses showed virtually no mechanical or chemical degradation. The findings propose a facile and inexpensive method to design stable and effective POM-based catalysts for HER in alkaline water electrolysis.     

Hatted 1T/2H-Phase MoS2 on Ni3S2 Nanorods for Efficient Overall Water Splitting in Alkaline Media

A new hatted 1T/2H-phase MoS₂ on Ni₃S₂ nanorods, as a bifunctional electrocatalyst for overall water splitting in alkaline media, is prepared through a simple one-pot hydrothermal synthesis. The hat-rod structure is composed mainly of Ni₃S₂, with 1T/2H-MoS₂ adhered to the top of the growth. Aqueous ammonia plays an important role in forming the 1T-phase MoS₂ by twisting the 2H-phase transition and expanding the interlayer spacing through the intercalation of NH₃/NH₄⁺. Owing to the special “hat-like” structure, the electrons conduct easily from Ni foam along Ni₃S₂ to MoS₂, and the catalyst particles maintain sufficient contact with the electrolyte, with gaseous molecules produced by water splitting easily removed from the surface of the catalyst. Thus, the electrocatalytic performance is enhanced, with an overpotential of 73 mV, a Tafel slope of 79 mV dec⁻¹, and excellent stability, and the OER demonstrates an overpotential of 190 mV and Tafel slope of 166 mV dec⁻¹.     

Electrocatalytic Hydrogen Production by a Nickel(II) Complex with a Phosphinopyridyl Ligand

A novel nickel(II) complex [Ni(L)₂Cl]Cl with a bidentate phosphinopyridyl ligand 6‐((diphenylphosphino)methyl)pyridin‐2‐amine (L) was synthesized as a metal‐complex catalyst for hydrogen production from protons. The ligand can stabilize a low Ni oxidation state and has an amine base as a proton transfer site. The X‐ray structure analysis revealed a distorted square‐pyramidal Ni^II complex with two bidentate L ligands in a trans arrangement in the equatorial plane and a chloride anion at the apex. Electrochemical measurements with the Ni^II complex in MeCN indicate a higher rate of hydrogen production under weak acid conditions using acetic acid as the proton source. The catalytic current increases with the stepwise addition of protons, and the turnover frequency is 8400 s^?1 in 0.1 m [NBu₄][ClO₄]/MeCN in the presence of acetic acid (290 equiv) at an overpotential of circa 590 mV.     

Flower-like Fe-Co-M (M=S,O, P and Se) Nanosheet Arrays Grown on Nickel Foam as High-efficiency Bifunctional Electrocatalysts

The development of highly efficient, inexpensive, abundant and non-precious metal electrocatalysts is the lifeblood of the hydrogen production industry, especially the hydrogen production industry by electrolysis of water. A Fe-Co-S/NF bifunctional electrocatalyst with nanoflower-like structure was synthesized on three-dimensional porous nickel foam through one-step hydrothermal and one-step high-temperature sulfuration operations, and the material displays high-efficiency electrocatalytic performance. As a catalyst for the hydrogen evolution reaction, Fe-Co-S/NF can drive a current density of 10 mA/cm² at an overpotential of 143 mV with a Tafel slope of 80.2 mV/dec. When it was used as an oxygen evolution reaction catalyst, it exhibits good OER reactivity with a low Tafel slope (82.6 mV/dec) and with requiring only 117 mV overpotential to drive current densities up to 50 mA/cm². In addition, the Fe-Co-S/NF//Fe-Co-S/NF electrolytic cell was assembled, an electrolysis voltage of 1.64 V is required to drive a current density of 50 mA/cm², which is one of the most active catalysts reported so far. This work indicates that the introduction of S, P and Se treating processes could effectively improve electrical conductivity of the material and enhance the catalytic activity of the material. This work offers an effective and convenient method for improving the morphology of the catalyst, increasing the surface area of the catalyst and developing high-efficiency and low-cost catalysts.     

Cuboid Ni2P as a Bifunctional Catalyst for Efficient Hydrogen Generation from Hydrolysis of Ammonia Borane and Electrocatalytic Hydrogen Evolution

The design of high‐performance catalysts for hydrogen generation is highly desirable for the upcoming hydrogen economy. Herein, we report the colloidal synthesis of nanocuboid Ni₂P by the thermal decomposition of nickel chloride hexahydrate (NiCl₂ ⋅ 6 H₂O) and trioctylphosphine. The obtained nanocuboid Ni₂P was characterized by using powder X‐ray diffraction, transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray photoelectron spectroscopy, and inductively coupled plasma atomic emission spectroscopy. For the first time, the as‐synthesized nanocuboid Ni₂P is used as a bifunctional catalyst for hydrogen generation from the hydrolysis of ammonia borane and electrocatalytic hydrogen evolution. Owing to the strong synergistic electronic effect between Ni and P, the as‐synthesized Ni₂P exhibits catalytic performance that is superior to its counterpart without P doping.     

Ni(OH)2纳米管的制备、表征及电化学性能

以多孔氧化铝为模板, 在不同溶液浓度下, 用化学沉积法制备了氢氧化镍纳米管. 采用XRD, SEM, TEM和HRTEM等手段, 对产物的物相、表面形貌及微结构进行了表征. 结果表明所得产物是高纯度的氢氧化镍纳米管, 外径约为180～220 nm, 管壁厚20～30 nm. 将所制备的氢氧化镍纳米管制成电极, 其电化学性能测试表明, Ni(OH)₂纳米管的中空结构特点, 能够有效地提高镍电极的充电效率、放电比容量、高倍率及高温放电性能. 机理分析表明中空结构的Ni(OH)₂纳米管对于提高碱性二次电池的综合性能有着极为重要的意义.     

(Ni-Co)-WC复合电极的析氢催化性能

采用 复合电沉 积方法获 得了（ Ｎｉ Ｃｏ） Ｗ Ｃ 复合电极 ,考 察了 复合 电极 在弱 酸性、碱性 和中性介质 中的析 氢电催化 性能,并 在弱酸性 介质中 进行了电 化学稳定 性实验 ． 结果 表明,复 合电极具有优越 的析氢 电催化性 能和良好 的电化 学稳定性 ．