An Efficient RuTe2/Graphene Catalyst for Electrochemical Hydrogen Evolution Reaction in Acid Electrolyte

Developing efficient powder catalysts for hydrogen evolution reaction (HER) in the acidic electrolyte is significant for hydrogen generation in the proton exchange membrane (PEM) water electrolysis technique. Herein, we demonstrated an efficient catalyst for HER in the acid media based on the graphene supported ruthenium telluride nanoparticles (RuTe₂/Gr). The catalysts were easily fabricated by a facile microwave irradiation/thermal annealing approach, and orthorhombic RuTe₂ crystals were found anchored over the graphene surface. The defective structure was demonstrated in the aberration‐corrected transmission electron microscopy images for RuTe₂ crystals and graphene support. This catalyst required an overpotential of 72 mV to drive 10 mA cm^?2 for HER when loading on the inert glass carbon electrode; Excellent catalytic stability in acidic media was also observed to offer 10 mA cm^?2 for 10 hours. The Volmer‐Tafel mechanism was indicated on RuTe₂/Gr catalyst by Tafel slope of 33 mV dec^?1, similar to that of Pt/C catalysts. The high catalytic performance of RuTe₂/Gr could be attributed to its high dispersion on the graphene surface, high electrical conductivity and low charge transfer resistance. This powder catalyst has potential application in the PEM water electrolysis technique because of its low cost and high stability.     

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.     

Amorphous Co-P Film: an Efficient Electrocatalyst for Hydrogen Evolution Reaction in Alkaline Seawater

Seawater electrolysis is considered an attractive alternative to conventional freshwater electrolysis for hydrogen production due to the abundance of seawater in nature. For this reason, efficient electrocatalysts for hydrogen evolution reaction (HER) in alkaline seawater are highly desired. In this study, we report an amorphous Co−P alloy on nickel foam (Co−P/NF) that behaves as an efficient and stable HER electrocatalyst for alkaline seawater electrolysis. The Co−P/NF presents high catalytic performance for HER, requiring a low overpotential of 213 mV to drive a current density of 100 mA cm⁻² and a Tafel slope of 120.2 mV dec⁻¹ in alkaline seawater. Furthermore, it shows remarkable electrochemical and structural stability in alkaline seawater.     

Bifunctional o-CoSe2/c-CoSe2/MoSe2 heterostructures for enhanced electrocatalytic and photoelectrochemical hydrogen evolution reaction

The bottleneck of alkaline hydrogen evolution reaction lies in the kinetically sluggish brought from multistep reaction processes involving water adsorption and dissociation, as well as hydrogen adsorption. In this work, we successfully synthesized o-CoSe₂/c-CoSe₂ heterostructures anchored on MoSe₂ nanosheets to powerfully promote reaction processes. As an electrocatalyst, it exhibits a low overpotential of 112 mV at 10 mA/cm² and a Tafel slope of 96.9 mV/dec for an alkaline hydrogen evolution reaction. Moreover, the as-prepared catalyst can behave as both cathode and anode for overall water splitting, which only requires 1.61 V cell voltage at 10 mA/cm². Significantly, the cell voltage can be further reduced to 1.53 V at 10 mA/cm² for water electrolysis under the simulated solar irradiation owing to such a semiconductor-based heterostructure that facilitates the separation of photogenerated charges. Here, the improving overall performance of this ternary electrocatalyst is attributed to the multifunctionality and synergistic interaction of different components in this heterogeneous material. The work provides a novel strategy to design active catalysts simultaneously using electric energy and solar energy for effective water splitting.     

The preparation of ionic liquid based iron phosphate/CNTs composite via microwave radiation for hydrogen evolution reaction and oxygen evolution reaction

Water electrolysis is a promising method for hydrogen production, so the preparation of low-cost and efficient electrocatalysts with a quick and simple procedure is crucial. Herein, iron phosphate (Fe₇(PO₄)₆) was prepared via microwave radiation using ionic liquid (IL) as iron and phosphorus dual-source. This method is simple and rapid, and the product can be directly used as electrocatalysts without further treatment. The experimental results show that the IL can influence the morphology and electrocatalytic performance. Moreover, the addition of carbon nanotubes (CNTs) is favorable for formation of iron phosphate nanoparticles to improve the catalytic activities. As hydrogen evolution reaction (HER) catalyst, this iron phosphate/CNTs exhibits an onset overpotential of 120 mV, Tafel slope of 32.9 mV dec^-1, and current densities of 10 mA cm⁻² at overpotential of 185 mV. Then, it obtains a good activity for oxygen evolution reaction (OER) with a low onset potential of 1.48 V, Tafel slope of 73.3 mV dec^-1, and it only needs an overpotential of 300 mV to drive the 10 mA cm⁻². This bifunctional catalyst also shows good durability for HER and OER. This microwave-assisted method provides an outstanding strategy to prepare iron phosphate in a simple and fast process with good catalytic performance for water splitting.     

Carbon Nanotubes Decorated with CoP Nanocrystals: A Highly Active Non‐Noble‐Metal Nanohybrid Electrocatalyst for Hydrogen Evolution

The development of effective and inexpensive hydrogen evolution reaction (HER) electrocatalysts for future renewable energy systems is highly desired. The strongly acidic conditions in proton exchange membranes create a need for acid‐stable HER catalysts. A nanohybrid that consists of carbon nanotubes decorated with CoP nanocrystals (CoP/CNT) was prepared by the low‐temperature phosphidation of a Co₃O₄/CNT precursor. As a novel non‐noble‐metal HER catalyst operating in acidic electrolytes, the nanohybrid exhibits an onset overpotential of as low as 40 mV, a Tafel slope of 54 mV dec^?1, an exchange current density of 0.13 mA cm^?2, and a Faradaic efficiency of nearly 100 %. This catalyst maintains its catalytic activity for at least 18 hours and only requires overpotentials of 70 and 122 mV to attain current densities of 2 and 10 mA cm^?2, respectively.     

One-Step Template/Solvent-Free Pyrolysis for In Situ Immobilization of CoP Nanoparticles onto N and P Co-Doped Carbon Porous Nanosheets towards High-efficiency Electrocatalytic Hydrogen Evolution

The search for economical, active and stable electrocatalysts towards the hydrogen evolution reaction (HER) is highly imperative for the progression of water electrolysis technology and related sustainable energy conversion technologies. The delicate optimization of chemical composition and architectural configuration is paramount to design high-efficiency non-precious metal HER electrocatalysts. Herein, we report a one-step scalable template/solvent-free pyrolysis approach for in situ immobilizing uniform CoP nanoparticles onto N and P co-doped carbon porous nanosheets (denoted as CoP@N,P-CNSs hereafter). The simultaneous consideration of architectural design and nanocarbon hybridization renders the formed CoP@N,P-CNSs with plentiful well-dispersed anchored active sites, shortened pathway for mass diffusion, enhanced electric conductivity, and reinforced mechanical stability. As a consequence, the optimized CoP@N,P-CNSs exhibit an overpotential of 115 mV to afford a current density of 10 mA cm⁻², small Tafel slope of 74.2 mV dec⁻¹, high Faradaic efficiency of nearly 100 %, and superb long-term durability in an alkaline medium. Given the fabrication feasibility, mass production potential and outstanding HER performance, the CoP@N,P-CNSs may hold great promise for large-scale electrochemical water splitting. More importantly, the explored one-step template/solvent-free pyrolysis methodology offers a feasible and versatile route to fabricate carbon nanosheet-based nanocomposites for diverse energy conversation-related applications.     

Pt nanodendrites with (111) crystalline facet as an efficient,stable and pH-universal catalyst for electrochemical hydrogen production

High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy. In this work, we report a robust and highly active catalyst fabricated through direct electrochemical deposition of Pt nanodendrites at the surface of activated carbon (Pt NDs). Owing to the large electrochemically active area and the exposed (111) facet of Pt, Pt NDs exhibits outstanding activity towards hydrogen evolution reaction with a low requiring overpotential of 0.027 V at 10 mA/cm² and Tafel slope of ≈ 22 mV/dec in acidic media. In addition, the hydrogen yield of Pt NDs is 30%–45% larger than that of commercial Pt/C at the same Pt loadings. Moreover, Pt NDs exhibits excellent long-term durability whose hydrogen production efficiency remains unchanged after six-hour hydrogen production, while the efficiency of commercial Pt/C catalyst decayed 9% under the same circumstance. Considering the superiority of catalytic activity and stability, this Pt NDs present great potentiality towards practical hydrogen production application.     

Tuning the Composition and Structure of Ni@MoC Nanosheets for Highly Active and Stable Electrocatalysis in Water Splitting

The conventional electrolytic water-splitting process for hydrogen production is plagued by high energy consumption, low efficiency, and the requirement of expensive catalysts. Therefore, finding effective, affordable, and stable catalysts to drive this reaction is urgently needed. We report a nanosheet catalyst composed of carbon nanotubes encapsulated with MoC/Mo₂C, the Ni@MoC-700 nanosheet showcases low overpotentials of 275 mV for the oxygen evolution reaction and 173 mV for the hydrogen evolution reaction at a current density of 10 mA ⋅ cm⁻². Particularly noteworthy is its outstanding performance in a two-electrode system, where a cell potential of merely 1.64 V is sufficient to achieve the desired current density of 10 mA ⋅ cm⁻². Furthermore, the catalyst demonstrates exceptional durability, maintaining its activity over a continuous operation of 40 hours with only minimal attenuation in overpotential. These outstanding activity levels and long-term stability unequivocally highlight the promising potential of the Ni@MoC-700 catalyst for large-scale water-splitting applications.     

MoSe2/Co-MOF/NF复合材料的制备及电催化产氧性能

设计高效的催化剂对于电解水制氢至关重要。基于过渡金属硒化物(TMSe)的高催化活性和金属有机骨架(MOFs)的灵活结构,我们提出了一种将MOFs与TMSe复合的策略,在导电基底泡沫镍(NF)上生长的复合材料不仅继承了2种单体的优点,还有效地改善了MOFs导电性差、TMSe易团聚的缺点。MoSe₂/Co-MOF/NF在碱性溶液中展示出优异的电催化产氧活性,在电流密度为10 mA·cm^-2时其过电位仅为242 mV,塔菲尔斜率仅为50.64 mV·dec^-1。此外,该材料在碱性溶液中经1 000圈循环伏安(CV)循环测试和30 h的恒电压电解测试均表现出良好的稳定性。     

泡沫镍原位负载双金属AlCo层状双氢氧化物纳米催化剂高效电催化析氧反应

经一步水热法在泡沫镍（NF）上原位生长获得了AlCo-LDH/NF （LDH=层状双氢氧化物）催化剂。基于AlCo-LDH的高表面积和良好相界面,催化剂表现出了优异的电催化析氧反应（OER）活性。在碱性介质中,当电流密度为200 mA·cm^-2时,AlCo₃-LDH/NF催化剂具有419 mV的低过电位和50.04 mV·dec^-1的低Tafel斜率。     

Controlled Synthesis of 3D Flower‐like Ni2P Composed of Mesoporous Nanoplates for Overall Water Splitting

Developing efficient non‐noble metal and earth‐abundant electrocatalysts with tunable microstructures for overall water splitting is critical to promote clean energy technologies for a hydrogen economy. Herein, novel three‐dimensional (3D) flower‐like Ni₂P composed of mesoporous nanoplates with controllable morphology and high surface area was prepared by a hydrothermal method and low‐temperature phosphidation as efficient electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Compared with the urchin‐like Ni_x P_y , the 3D flower‐like Ni₂P with a diameter of 5 μm presented an efficient and stable catalytic performance in 0.5 m H₂SO₄, with a small Tafel slope of 79 mV dec⁻¹ and an overpotential of about 240 mV at a current density of 10 mA cm⁻² with a mass loading density of 0.283 mg cm⁻². In addition, the catalyst also exhibited a remarkable performance for the OER in 1.0 m KOH electrolyte, with an overpotential of 320 mV to reach a current density of 10 mA cm⁻² and a small Tafel slope of 72 mV dec⁻¹. The excellent catalytic performance of the as‐prepared Ni₂P may be ascribed to its novel 3D morphology with unique mesoporous structure.     

Ru Nanoparticles Supported on Co-Embedded N-Doped Carbon Nanotubes as Efficient Electrocatalysts for Hydrogen Evolution in Basic Media

A challenging but urgent task is to construct efficient and robust hydrogen evolution reaction(HER) electrocatalysts for practically feasible and sustainable hydrogen production through alkaline water electrolysis. Herein we report a simple and mild pyrolysis method to synthesize the efficient Ru nanoparticles(NPs) supported on Co-embedded N-doped carbon nanotubes(Ru/Co-NCNTs) catalyst for HER in basic media. The Ru/Co-NCNTs display remarkable performance with a low overpotential of only 35 mV at 10 mA/cm², a small Tafel slope(36 mV/dec), and a high mass activity in 1 mol/L KOH, which is superior to commercial 20% Pt/C catalyst. This excellent performance is benefited from the enhanced conductivity of N-doped carbon nanotubes(NCNTs) and high intrinsic activity triggered by synergistic coupling between Ru NPs and Co-embedded N-doped carbon nanotubes(Co-NCNTs).     

MoSe2/Co-MOF/NF复合材料的制备及电催化产氧性能

设计高效的催化剂对于电解水制氢至关重要。基于过渡金属硒化物(TMSe)的高催化活性和金属有机骨架(MOFs)的灵活结构，我们提出了一种将MOFs与TMSe复合的策略，在导电基底泡沫镍(NF)上生长的复合材料不仅继承了2种单体的优点，还有效地改善了MOFs导电性差、TMSe易团聚的缺点。MoSe₂/Co-MOF/NF在碱性溶液中展示出优异的电催化产氧活性，在电流密度为10 mA·cm^-2时其过电位仅为242 mV，塔菲尔斜率仅为50.64 mV·dec^-1。此外，该材料在碱性溶液中经1 000圈循环伏安(CV)循环测试和30 h的恒电压电解测试均表现出良好的稳定性。     

Optimizing Electronic and Geometrical Structure of Vanadium Doped Cobalt Phosphides for Enhanced Electrocatalytic Hydrogen Evolution

Despite the expectation on transition-metal phosphides as precious-metal-free electrocatalysts, the reported performance of these materials still necessitates further improvement. Ingenious regulations of both geometric and electronic structure have been proposed as an effective approach to boost their electrocatalytic properties. In this regard, the self-supported V doped CoP nanowires on nickel foam are prepared to accommodate both optimized electronic structure and desired nanostructure, which enable large surface area, abundant active sites exposure, low charge transfer resistance, as well as favorable H* adsorption. As for the alkaline hydrogen evolution, it only requires a lower potential of 79 mV and 125 mV to drive 10 mA ⋅ cm⁻² and 100 mA ⋅ cm⁻² current with a Tafel slope of 47.41 mV ⋅ dec⁻¹, which prevails over commercial Pt/C catalysts. The catalyst also exhibits excellent durability to retain activity unchanged for more than 16 h. Such a simple and convenient strategy by electronic tuning and structure design provides a new avenue toward the exploration of efficient electrocatalysts.     

Phosphorus‐Modified Tungsten Nitride/Reduced Graphene Oxide as a High‐Performance,Non‐Noble‐Metal Electrocatalyst for the Hydrogen Evolution Reaction

Phosphorus‐modified tungsten nitride/reduced graphene oxide (P‐WN/rGO) is designed as a high‐efficient, low‐cost electrocatalyst for the hydrogen evolution reaction (HER). WN (ca. 3 nm in size) on rGO is first synthesized by using the H₃[PO₄(W₃O₉)₄] cluster as a W source. Followed by phosphorization, the particle size increase slightly to about 4 nm with a P content of 2.52 at %. The interaction of P with rGO and WN results in an obvious increase of work function, being close to Pt metal. The P‐WN/rGO exhibits low onset overpotential of 46 mV, Tafel slope of 54 mV dec^?1, and a large exchange current density of 0.35 mA cm^?2 in acid media. It requires overpotential of only 85 mV at current density of 10 mA cm^?2, while remaining good stability in accelerated durability testing. This work shows that the modification with a second anion is powerful way to design new catalysts for HER.     

Proton-induced fast preparation of size-controllable MoS_2 nanocatalyst towards highly efficient water electrolysis

MoS_2 has emerged for catalyzing the hydrogen evolution reaction.Various notable strategies have been developed to downsize the MoS_2 particles and expose more active edges.However,the restacking issue,which reduces the exposure degree,has rarely been taken into account.Herein,we report on a facile proton-induced fast hydrothermal approach to produce size-controllable MoS_2 nanocatalysts and demonstrate that along the varying of sheet sizes,there is a trade-off between the intrinsic catalytic activity(mainly determined by the unsaturated sulfur on the sheet edges) and the active edge accessibility(influenced by the assembly structure).The size-optimized catalyst delivers a high performance of a low overpotential of～200 mV at 10 mA/cm2,a Tafel slope of 46.3 mV/dec,and a stable working state,which is comparable to the recent notable works.Our findings will provide a pathway for its large-scale application and enhance the water electrolysis performance.     

Graphitic Carbon Nitride Nanoribbons: Graphene‐Assisted Formation and Synergic Function for Highly Efficient Hydrogen Evolution

The development of new promising metal‐free catalysts is of great significance for the electrocatalytic hydrogen evolution reaction (HER). Herein, a rationally assembled three‐dimensional (3D) architecture of 1D graphitic carbon nitride (g‐C₃N₄) nanoribbons with 2D graphene sheets has been developed by a one‐step hydrothermal method. Because of the multipathway of charge and mass transport, the hierarchically structured g‐C₃N₄ nanoribbon–graphene hybrids lead to a high electrocatalytic ability for HER with a Tafel slope of 54 mV decade^?1, a low onset overpotential of 80 mV and overpotential of 207 mV to approach a current of 10 mA cm^?2, superior to those non‐metal materials and well‐developed metallic catalysts reported previously. This work presents a great advance for designing and developing highly efficient metal‐free catalyst for hydrogen evolution.     

NiFe水滑石纳米片阵列负载Ru用于提升碱性电催化析氢和析氧性能

通过离子交换的方式将Ru负载到NiFe水滑石(LDH)纳米阵列表面得到(Ru/NiFe LDH),Ru的引入显著提升了NiFe LDH的活性比表面积,暴露了更多的活性位点,同时调控了其电子结构,大大提升了其本征催化活性。在碱性条件下,催化析氢反应时仅需50 mV的过电位即可达到10 mA·cm^-2的电流密度,Tafel斜率为52.3 mV·dec^-1。而相同条件下原始NiFe LDH达到10mA·cm^-2的电流密度则需要226 mV的过电位,Tafel斜率为157.5 mV·dec^-1。同时制备的Ru/NiFe LDH也展现出了良好的析氧催化活性,在50 mA·cm^-2的电流密度下,过电位仅为231 mV,而NiFe LDH则需237 mV。Ru/NiFe LDH在长时间的电催化条件下依然能保持良好的工作稳定性。     

Electrochemical performance of grown layer of Ni(OH)2 on nickel foam and treatment with phosphide and selenide for efficient water splitting

Active nanocomposites synthesized by the electrochemical approach play a vital role in energy generation, conversion, and storage technologies. Recently, scientists began to explore the use of earth-rich transition metal-based materials to replace precious metal-based catalysts. Transition metals (TMs) based nickel (Ni) and their pnictides compounds such as phosphides and selenides exhibit good activity for hydrogen evaluation reaction (HER) and the entire water electrolysis process. In this study, we first prepared Ni(OH)₂ and grown its layer on Ni foam (NF) and treated it with selenide (Se) and phosphide (P) then nickel-based selenide-phosphide catalyst (Ni–P–Se) was prepared by simultaneous selenization and phosphidation process for the first time. The as-obtained composite was then analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), elemental mapping and transmission electron microscope (TEM) means to study the composition, structure, and micro-morphology of materials. Furthermore, we also observed electrocatalytic water splitting activity using electrochemical cell. The results of electrochemical tests depicted that the selenization and phosphidation treatments significantly enhanced the electrocatalytic HER activity of the starting materials. The overpotentials required for Ni–P–Se to reach 10 ?mA ?cm^?2 and 100 ?mA ?cm^?2 were only 242 ?mV and 282 ?mV. The Tafel slope of Ni–P–Se is 151 ?mV dec^?1, which is lower than that of nickel phosphide, selenide, and hydroxide indicating that selenide-phosphide enhances the HER reaction kinetics of the material, which in turn increases hydrogen output rate as compared with previous studies.