Plasma-modified iron-doped Ni3S2 nanosheet arrays as efficient electrocatalysts for hydrogen evolution reaction

The development of efficient transition-metal catalysts for the hydrogen evolution reaction is significant to meeting global energy demands. In this study, to realize a high-performance electrocatalyst, we synthesize an Fe-doped Ni₃S₂ nanosheet material in situ on 3D structured nickel foam via the hydrothermal sulfide method, and then modify it by the dielectric barrier discharge plasma technique. Combining Fe atom doping and plasma modification increases the electrochemical surface area, provides an abundance of active sites, optimizes the electronic structure, and accelerates the reaction kinetics, thereby improving catalytic activity. As a result, the PA@Fe_1/4-Ni₃S₂/NF catalyst exhibits excellent hydrogen evolution reaction activity, only requires ultra-low overpotentials to achieve a current density of 10 mA cm^?2, and exhibits excellent durability. This study proposes a novel method for rationally designing non-noble metal electrocatalysts.     

Assembling Co_9S_8 nanoflakes on Co_3O_4 nanowires as advanced core/shell electrocatalysts for oxygen evolution reaction

Rational design of advanced cost-effective electrocatalysts is vital for the development of water electrolysis. Herein, we report a novel binder-free efficient Co_9S_8@Co_3O_4 core/shell electrocatalysts for oxygen evolution reaction(OER) via a combined hydrothermal-sulfurization method. The sulfurized net-like Co_9S_8 nanoflakes are strongly anchored on the Co_3O_4 nanowire core forming self-supported binder-free core/shell electrocatalysts. Positive advantages including larger active surface area of Co_9S_8 nanoflakes,and reinforced structural stability are achieved in the Co_9S_8@Co_3O_4 core/shell arrays. The OER performances of the Co_9S_8@Co_3O_4 core/shell arrays are thoroughly tested and enhanced electrocatalytic performance with lower over-potential(260 m V at 20 m A cm~(-2)) and smaller Tafel slopes(56 mV dec-1) as well as long-term durability are demonstrated in alkaline medium. Our proposed core/shell smart design may provide a new way to construct other advanced binder-free electrocatalysts for applications in electrochemical catalysis.     

Fe-doped Co_3O_4@C nanoparticles derived from layered double hydroxide used as efficient electrocatalyst for oxygen evolution reaction

Compared with noble metal catalyst, Co_3O_4-based electrocatalysts have attracted considerable interesting as low-cost alternatives for oxygen evolution reaction(OER). However, the poor electrocatalytic activity still remains a huge challenge. Herein, we demonstrate a feasible approach through oxidation of CoFe layered double hydroxide(CoFe-LDH) to synthesize Fe-doped Co_3O_4@C nanoparticles with size of about30–50 nm. As OER catalyst, the as-synthesized Fe-doped Co_3O_4@C nanoparticles exhibited superior OER performance with a small overpotential of 260 mV at the current density of 20 mA cm~(-2), a small Tafel slope of 70 mV dec~(-1) and long-term durability(there was no obviously OER current density degradation for 100 h) in alkaline solution. The present work opens a new avenue to the exploration of cost-effective and excellent electrocatalysts based on transition metal oxide materials to substitute precious metal materials for water splitting.     

Design of efficient electrocatalysts for hydrogen evolution reaction based on 2D MXenes

The growing energy concern all over the world has recognized hydrogen energy as the most promising renewable energy sources.Recently,electrocatalytic hydrogen evolution reaction(HER)by water splitting has been extensively studied with a focus on developing efficient electrocatalysts that can afford HER at overpotential with minimum power consumption.The two-dimensional transition metal carbides and nitride,also known as MXenes,are becoming the rising star in developing efficient electrocatalysts for HER,owing to their integrated chemical and electronic properties,e.g.,metallic conductivity,variety of redox-active transition metals,high hydrophilicity,and tunable surface functionalities.In this review,the recent progress about the fundamental understanding and materials engineering of MXenes-based electrocatalysts is summarized in concern with two aspects:i)the regulation of the intrinsic properties of MXenes,which include the composition,surface functionality,and defects;and ii)MXenes-based composites for HER process.In the end,we summarize the present challenges concerning the efficiency of MXenes-based HER electrocatalysts and propose the directions of future research efforts.     

Ternary NiCoFe-layered double hydroxide hollow polyhedrons as highly efficient electrocatalysts for oxygen evolution reaction

正With exhaustion of fossil fuels and the deterioration of global environment,widespread and intensive researches have been concentrated on clean and sustainable alternative energy sources,such as metal-air batteries ~([1]),fuel cells ~([2]) and water splitting devices [3].Electrocatalytic oxidation of water to O_2 (oxygen     

Glucose-derived carbon sphere supported CoP as efficient and stable electrocatalysts for hydrogen evolution reaction

Glucose-derived carbon sphere supported cobalt phosphide nanoparticles(Co P/C) were synthesized via a concise two-step method. The electrochemical measurement results indicate that the Co P/C prepared at 900 ℃ presents excellent electrocatalytic performance for hydrogen evolution reaction(HER). The overpotential at a current density of 10 m A cm~(-2) is 108 and 163 mV in 0.5 M H_2SO_4 and 1 M KOH, respectively, and maintains its electrocatalytic durability for at least 10 h. This work supplies a new field to challenge the construction of electrocatalysts for HER through using cost-effective carbon supported transition metal phosphides.     

CoS2 nanowires supported graphdiyne for highly efficient hydrogen evolution reaction

Transition metal sulfides are an important category for hydrogen evolution reaction(HER).However,only few edge unsaturated sulfurs functionalize as catalytic si...     

High-precision regulation synthesis of Fe-doped Co_2P nanorod bundles as efficient electrocatalysts for hydrogen evolution in all-pH range and seawater

The hydrogen evolution reaction(HER)via water electrolysis has gained immense research attention.Seawater electrolysis provides great opportunities for sustainable energy production,but is extremely challenging.Transition metal phosphides are promising candidate electrocatalysts.Herein,we prepared a novel Fe-Co₂P bundle of nanorods(BNRs)for catalyzing the HER in seawater electrolysis and over the entire p H range.Cobalt phosphides with different crystal phases and morphologies were obtained by varying the Fe doping amount.The Co:Fe molar ratio of 1:0.5 was found to be optimum.The Fe doping improved the HER performance of Co₂P over the entire p H range by providing favorable electronic properties and morphology,lattice distortion,and special coordination environment.The Fe-Co₂P BNRs showed higher catalytic activity than 20%Pt/C in seawater at high potentials.The density functional theory calculations revealed that the Fe doping reduced the hydrogen binding strength of Co₂P to efficiently accelerate the HER kinetics and produce a favorable charge density.This study provides valuable insights into the design and development of high-efficiency HER catalysts for large-scale seawater electrolysis.     

Facile one-step synthesis of Ru doped NiCoP nanoparticles as highly efficient electrocatalysts for oxygen evolution reaction

Transition metal phosphides (TMPs) as ever-evolving electrocatalytic materials have attracted increasing attention in water splitting reactions owing to their cost-effective, highly active and stable catalytic properties. This work presents a facile synthetic route to NiCoP nanoparticles with Ru dopants which function as highly efficient electrocatalysts for oxygen evolution reaction (OER) in alkaline media. The Ru dopants induced a high content of Ni and Co vacancies in NiCoP nanoparticles, and the more defective Ru doped NiCoP phase than undoped NiCoP ones led to a greater number of catalytically active sites and improved electrical conductivity after undergoing electrochemical activation. The Ru doped NiCoP catalyst exhibited high OER catalytic performance in alkaline media with a low overpotential of 281 mV at 10 mA cm⁻² and a Tafel slope of 42.7 mV dec⁻¹.     

Ultrathin NiFeS nanosheets as highly active electrocatalysts for oxygen evolution reaction

The development of efficient and cost-effective oxygen evolution reaction (OER) electrocatalysts is crucial for clean energy conversion and storage devices, such as water-splitting, CO₂ reduction, and metal-air batteries. Herein, we report an efficient 2-dimensional OER catalyst of ultrathin nickel-iron sulfide nanosheets (NiFeS-NS). Dodecanethiol is employed in the synthesis, which prohibits the growth along the Z-axis, thus a nanosheet is obtained. The NiFeS-NS shows high OER catalytic activity, which only requires a small overpotential of 273 mV to achieve the OER current density of 10 mA/cm² in alkaline electrolyte, and almost no decay after 150 h of chronopotentiometry test. The high performance is attributed to the 2-dimensional structure, the synergistic effect from the Ni and Fe components which promotes the formation of the high valence Ni species, and the tuning effect from the in-situ generated sulfate doping. This work demonstrates the advantages of the 2-dimensional sulfides in electrocatalysis.     

The design and fabrication of Co_3O_4/Co_3V_2O_8/Ni nanocomposites as high-performance anodes for Li-ion batteries

The Co_3O_4/Co_3V_2O_8/Ni nanocomposites were rationally designed and prepared by a two-step hydrothermal synthesis and subsequent annealing treatment. The one-dimensional(1D) Co_3O_4 nanowire arrays directly grew on Ni foam, whereas the 1D Co_3V_2O_8 nanowires adhered to parts of Co_3O_4 nanowires.Most of the hybrid nanowires were inlayed with each other, forming a 3D hybrid nanowires network.As a result, the discharge capacity of Co_3O_4/Co_3V_2O_8/Ni nanocomposites could reach 1201.8 mAh/g after100 cycles at 100 mA/g. After 600 cycles at 1 A/g, the discharge capacity was maintained at 828.1 mAh/g.Moreover, even though the charge/discharge rates were increased to 10 A/g, it rendered reversible capacity of 491.2 mAh/g. The superior electrochemical properties of nanocomposites were probably ascribed to their unique 3D architecture and the synergistic effects of two active materials. Therefore, such Co_3O_4/Co_3V_2O_8/Ni nanocomposites could potentially be used as anode materials for high-performance Li-ion batteries.     

Promoted porous Co_3O_4-Al_2O_3 catalysts for ammonia decomposition

Transition metal catalysts have been considerably used for NH_3 decomposition because of the potential application in CO_x-free H_2 generation for fuel cells.However,most transition metal catalysts prepared via traditional synthetic approaches performed the inferior stability due to the agglomeration of active components.Here,we adopted an efficient method,aerosol-assisted selfassembly approach(AASA),to prepare the optimized cobalt-alumina(Co_3O_4-Al_2O_3)catalysts.The Co_3O_4-Al_2O_3catalysts exhibited excellent catalytic performance in the NH_3 decomposition reaction,which can reach 100%conversion at 600°C and maintain stable for 72 h at a gaseous hourly space velocity(GHSV)of 18000 cm~3g~(-1)_(cat)h~(-1).The catalysts were characterized by various techniques including transmission electron microscope(TEM),scanning electron microscope(SEM),nitrogen sorption,temperature-programmed reduction by hydrogen(H_2-TPR),ex-situ/in-situ Raman and ex-situ/in-situ X-ray diffraction(XRD)to obtain the information about the structure and property of the catalysts.H_2-TPR and in-situ XRD results show that there is strong interaction between the cobalt and alumina species,which influences the redox properties of the catalysts.It is found that even a low content of alumina(10 at%)is able to stabilize the catalysts due to the adequate dispersion and rational interaction between different components,which ensures the high activity and superior stability of the cobalt-alumina catalysts.     

Dopamine-assisted synthesis of rGO@NiPd@NC sandwich structure for highly efficient hydrogen evolution reaction

Journal of Solid State Electrochemistry - We report a facile one-pot solvothermal synthesis of NiPd alloy homogeneously encapsulated between reduced graphene oxide sheets and N-doped carbon layers...     

An insight to catalytic synergic effect of Pd-MoS2 nanorods for highly efficient hydrogen evolution reaction

The electrocatalytic hydrogen evolution reaction (HER) is a sustainable energy production route using green chemistry. Transition metal dichalcogenides' application in catalytic hydrogen production is limited due to a lack of solutions that simultaneously address intrinsic activity, increased surface area, electrical conductivity, and stability problems. Herein we address these issues simultaneously by modifying the electronic structure of molybdenum disulfide (MoS₂) nanorods using a low content of Pd (1 wt% and 2 wt%) dopant via a facile colloidal solvothermal route. The resulting MoS₂ nanorods doped with (1 and 2 wt%) palladium demonstrate current density of 100 mA/cm² at quit lower over-potentials of 137 mV and 119 mV than 273 mV for pure MoS₂ nanorods, accompanied by high stability. This research proposes a strategy for designing high-performance HER electrocatalysts that work in acidic medium. In addition, the Tafel slop calculated for MoS₂ is 112 mV/dec whereas for 1 and 2 wt% Pd-MoS₂, the Tafel slopes are 70 mV/dec and 46 mV/dec.     

Nanoporous graphitic-C3N4@carbon metal-free electrocatalysts for highly efficient oxygen reduction

Based on theoretical prediction, a g-C(3)N(4)@carbon metal-free oxygen reduction reaction (ORR) electrocatalyst was designed and synthesized by uniform incorporation of g-C(3)N(4) into a mesoporous carbon to enhance the electron transfer efficiency of g-C(3)N(4). The resulting g-C(3)N(4)@carbon composite exhibited competitive catalytic activity (11.3 mA cm(-2) kinetic-limiting current density at -0.6 V) and superior methanol tolerance compared to a commercial Pt/C catalyst. Furthermore, it demonstrated significantly higher catalytic efficiency (nearly 100% of four-electron ORR process selectivity) than a Pt/C catalyst. The proposed synthesis route is facile and low-cost, providing a feasible method for the development of highly efficient electrocatalysts.     

超微粒CO3O4的合成与表征

本文用胶溶法合成了纳米级超微粒Co_3O_4,初步探讨了合成Co_3O_4超微粒的最佳实验条件,对产品的结构性能测试表明,所得超微粒子Co_3O_4粒度均匀,平均粒度为4.0nm.200℃热处理时,产品为无定形,在许多有机溶剂中具有良好的分散性和透明性;400℃热处理得到立方Co_3O_4纳米晶体,平均粒度为6.0nm,热稳定性好。     

N-doped Mo2C nanoblock for efficient hydrogen evolution reaction

Journal of Solid State Electrochemistry - The development of Pt-free electrocatalysts for hydrogen evolution reaction (HER) is still desired in water-splitting as a clean energy. As a highly...     

Studies of Nano-sized Co_3O_4 as Anode Materials for Lithium-ion Batteries

Introduction　　Thelargecapacityandhighcellvoltageoflithium basedcells ,coupledwiththeirrelativelylowenvironmen talimpactmakethemanidealcandidateforportablepowersupplies .Studyonpresentmaterialsforlithiumionbatter iesfocusesonimprovingcycleabilityandincreasingca pacityofelectrodematerials.Asoneoftheimportantpartsoflithium ionbatteries ,anodematerialshavebeeninvestigatedintensively .Now ,carbonaceousmaterialsareusedinnearlyalllithiumionbatteriesbecauseoftheirhighcapacity (theoreticalcapaci tyof…     

3D nitrogen-doped graphene aerogel-supported Fe3O4 nanoparticles as efficient electrocatalysts for the oxygen reduction reaction

Three-dimensional (3D) N-doped graphene aerogel (N-GA)-supported Fe(3)O(4) nanoparticles (Fe(3)O(4)/N-GAs) as efficient cathode catalysts for the oxygen reduction reaction (ORR) are reported. The graphene hybrids exhibit an interconnected macroporous framework of graphene sheets with uniform dispersion of Fe(3)O(4) nanoparticles (NPs). In studying the effects of the carbon support on the Fe(3)O(4) NPs for the ORR, we found that Fe(3)O(4)/N-GAs show a more positive onset potential, higher cathodic density, lower H(2)O(2) yield, and higher electron transfer number for the ORR in alkaline media than Fe(3)O(4) NPs supported on N-doped carbon black or N-doped graphene sheets, highlighting the importance of the 3D macropores and high specific surface area of the GA support for improving the ORR performance. Furthermore, Fe(3)O(4)/N-GAs show better durability than the commercial Pt/C catalyst.     

Electron-transfer enhanced MoO2-Ni heterostructures as a highly efficient pH-universal catalyst for hydrogen evolution

Hydrogen is one of the most promising energy carriers to replace fossil fuels and electrolyzing water to produce hydrogen is a very effective method. However, designing highly active and stable non-precious metal hydrogen evolution electrocatalysts that can be used in universal pH is a huge challenge. Here, we have reported a simple strategy to develop a highly active and durable non-precious MoO_2-Ni electrocatalyst for hydrogen evolution reaction(HER) in a wide pH range. The MoO_2-Ni catalyst exhibits a superior electrocatalytic performance with low overpotentials of 46, 69, and 84 mV to reach-10 mA cm~(-2) in 1.0 M KOH, 0.5 M H_2SO_4,and 1.0 M PBS electrolytes, respectively. At the same time, the catalyst also shows outstanding stability over a wide pH range. It is particularly noted that the catalytic performance of MoO_2-Ni in alkaline solution is comparable to the highest performing catalysts reported. The outstanding HER performance is mainly attributed to the collective effect of the rational morphological design, electronic structure engineering, and strong interfacial coupling between MoO_2 and Ni in heterojunctions.This work provides a viable method for the synthesis of inexpensive and efficient HER electrocatalysts for the use in wide pH ranges.