过渡金属磷硫化物加氢精制及电催化析氢反应性能研究

以硫脲为固体硫化剂、相应过渡金属磷酸盐为前驱体,采用程序升温还原的方法制备了Co_(2)P、MoP和WP的磷硫化物。结果表明,添加硫脲后制备的催化剂结晶度和粒度都有所降低。在酸性条件下电催化析氢反应(HER)中,磷硫化物活性随前驱体中硫脲质量分数的增加呈先增加后降低的趋势。制备Co_(2)P、MoP和WP的磷硫化物时前驱体中最佳的硫脲质量分数分别为26%、33%和33%。过渡金属磷化物催化HER、杂环含氮化合物加氢以及二苯并噻吩(DBT)加氢脱硫(HDS)活性顺序均为MoP>WP>Co_(2)P,说明这些反应之间存在内在联系。

Ru Cs/Mo_(2)C纳米棒制备及电催化析氢的研究

Mo_(2)C被誉为最有前景的电催化产氢催化剂,然而其高的过电压和低效率限制了其规模化生产。本文通过简单的溶剂热法制备了Ru纳米簇(Ru Cs/Mo_(2)C)负载Mo_(2)C纳米棒复合材料。研究表明,Ru Cs/Mo_(2)C(Ru,质量分数7.79%)表现出优异的电催化产氢性能,电流密度在10 mA·cm^(-2)的过电势为104 mV,Tafel斜率为96.30 mV·dec^(-1)。同时,Ru Cs/Mo_(2)C催化剂具有优异的稳定性,在工业电解系统中具有广阔的应用前景。

MoS_2/核桃壳活性炭复合纳米材料的制备及其电催化析氢性能研究

以钼酸铵为钼源、硫脲为硫源,使用核桃壳活性炭通过水热法成功制备二硫化钼(MoS_2)/核桃壳活性炭复合纳米材料。研究了MoS_2含量对复合纳米材料形貌、尺寸及电化学性能的影响,通过X射线粉末衍射仪、冷场发射扫描电子显微镜、比表面积及孔隙度分析仪、线性扫描伏安法对复合纳米材料的结构、形貌、电化学性能进行分析和表征。结果表明,MoS_2质量分数为80%的MoS_2/核桃壳活性炭复合纳米材料的电催化析氢反应活性最好。

面向多功能非贵金属电催化剂的构筑和微尺度解析

相对于贵金属电催化剂制作成本高、地球储量稀少、电化学稳定性低等缺点,制备廉价、能量转换效率高、使用寿命长、环境友好的非贵金属电催化剂是推动能源存储和转换技术快速发展的重要途径。根据电催化过程中电催化析氢反应(Hydrogen Evolution Reaction,HER)、电催化析氧反应(Oxygen Evolution Reaction,OER)及氧还原反应(Oxygen Reduction Reaction,ORR)这三个重要反应类型,概述了水裂解和燃料电池的电化学反应机制,同时归纳了单功能电催化剂、双功能电催化剂、多功能电催化剂及其他电化学材料的设计与制备方法、相互关系和各自功能特点。借助先进的电子显微技术,如扫描电子显微镜、原子力扫描电子显微镜、透射电子显微镜、X射线能谱仪、电子能量损失谱仪等对其微观结构进行表征,重点对其表面形貌、结构、内部成分、元素分布等相关信息进行解析。从提供更丰富的缺陷空位、潜在活性位点、优化界面相互作用、增大电化学比表面积、形成协同效应等方面,分析其在降低成本的同时,提高电催化剂的电导率、增强稳定性的相关机理,以期为非贵金属电催化剂的研究和推广应用提供新策略。

金箔上单层MoS_2的控制生长及电催化析氢应用

金属衬底上单层Mo S2的可控批量制备是探索其微观形貌、新奇物理化学特性以及潜在应用的重要前提.最近,我们利用低压化学气相沉积的方法,在多晶金箔上实现了高质量、大面积/大批量、畴区尺寸可调(从几百纳米到几十微米)单层Mo S2的可控制备;利用低能电子显微/衍射实现了直接生长的单层Mo S2畴区取向和畴区边界的原位识别;利用金箔上合成的纳米尺寸Mo S2作为电催化析氢反应的催化剂,实现了高效的析氢效果(塔菲尔斜率约61 m V/dec,交换电流密度约38.1μA/cm2).本文将以这些研究成果为主线,系统地阐述金箔上单层Mo S2的可控制备和转移、畴区的原位识别以及在电催化析氢反应中的应用,并对该领域的未来发展趋势和所面临的挑战进行简要的展望.

Amorphous core-shell NiMoP@CuNWs rod-like structure with hydrophilicity feature for efficient hydrogen production in neutral media

Using interface engineering,a highly efficient catalyst with a shell@core structure was successfully synthesized by growing an amorphous material composed of Ni,Mo,and P on Cu nanowires(Ni-MoP@CuNWs).This catalyst only requires an overpotential of 35 mV to reach a current density of 10 mA cm^(-2).The exceptional hydrogen evolution reaction(HER)activity is attributed to the unique amorphous rod-like nature of NiMoP@CuNWs,which possesses a special hydrophilic feature,en-hances mass transfer,promotes effective contact between the electrode and electrolyte solution,and exposes more active sites during the catalytic process.Density functional theory revealed that the introduction of Mo weakens the binding strength of the Ni site on the catalyst surface with the H atom and promotes the desorption process of the H_(2) product significantly.Owing to its facile syn-thesis,low cost,and high catalytic performance,this electrocatalyst is a promising option for com-mercial applications as a water electrolysis catalyst.

Recent advances in design of hydrogen evolution reaction electrocatalysts at high current density:A review

The electrolysis of water powered by renewable energy sources offers a promising method of"green hydrogen"production,which is considered to be at the heart of future carbon-neutral energy systems.In the past decades,researchers have reported a number of hydrogen evolution reaction(HER)electrocatalysts with activity comparable to that of commercial Pt/C,but most of them are tested within a small current density range,typically no more than 500 mA cm^(-2).To realize the industrial application of hydrogen production from water electrolysis,it is essential to develop high-efficiency HER electrocatalysts at high current density(HCD≥500 mA cm^(-2)).Nevertheless,it remains challenging and significant to rational design HCD electrocatalysts for HER.In this paper,the design strategy of HCD electrocatalysts is discussed,and some HCD electrocatalysts for HER are reviewed in seven categories(alloy,metal oxide,metal hydroxide,metal sulfide/selenide,metal nitride,metal phosphide and other derived electrocatalysts).At the end of this article,we also pro-pose some viewpoints and prospects for the future development and research directions of HCD electrocatalysts for HER.

Strategies on improving the electrocatalytic hydrogen evolution performances of metal phosphides

Among the sustainable energy sources,hydrogen is the one most promising for alleviating the pollution issues related to the usage of conventional fuels,as it can be produced in an efficient and eco-friendly way via electrocatalytic water splitting.The hydrogen evolution reaction(HER,a half-reaction of water splitting)plays a pivotal role in decreasing the price and increasing the catalytic efficiency of hydrogen production and is efficiently promoted by metal phosphides in different electrolytes.Herein,we summarize the recent advances in the development of metal phosphides as HER electrocatalysts,focus on their synthesis(post-treatment,in situ generation,and electrodeposition methods)and the enhancement of their electrocatalytic activity(via elemental doping,interface and vacancy engineering,construction of specific supports and nanostructures,and the design of bior polymetallic phosphides),and highlight the crucial issues and challenges of future development.

Sustainable synthesis of supported metal nanocatalysts for electrochemical hydrogen evolution

Among the various types of heterogeneous catalysts,supported metal nanocatalysts(SMNCs)have attracted widespread interest in chemistry and materials science,due to their advantageous features,such as high efficiency,stability,and reusability for catalytic reactions.However,to obtain well-defined SMNCs and inhibit nanoparticle aggregation,traditional approaches generally involve numerous organic reagents,complex steps,and specialized equipment,thus hindering the practical and large-scale synthesis of SMNCs.In this review,we summarize green and sustainable synthetic methodologies for the assembly of SMNCs,including low temperature pyrolysis and solid-state,surfactant-and reductant-free,and ionic liquid assisted syntheses.The conventional application of SMNCs for electrochemical hydrogen evolution and the corresponding achievements are subsequently discussed.Finally,future perspectives toward the sustainable production of SMNCs are presented.

Co0.85Se magnetic nanoparticles supported on carbon nanotubes as catalyst for hydrogen evolution reaction

Co0.85Se magnetic nanoparticles supported on carbon nanotubes were prepared by a one‐step hydrothermal method.The saturation magnetization and coercivity of the MWCNTs/Co0.85Se nanocomposites increased due to a decrease in the Co0.85Se nanoparticle size in the MWCNTs/Co0.85Se nanocomposites and an increase in the distance between the Co0.85Se nanoparticles,which increased the specific surface area,thereby benefiting the electrocatalytic performance of the catalyst.Moreover,the MWCNTs/Co0.85Se nanocomposites exhibited an excellent hydrogen evolution reaction performance owing to the presence of MWCNTs,which enhanced the mass transport during the electrocatalytic reactions.Furthermore,in an acid solution,the 30 wt%MWCNTs/Co0.85Se composite catalyst exhibited a current density of 10 mA cm^‒2 at a small overpotential of 266 mV vs.RHE,a small Tafel slope of 60.5 mV dec^‐1,and good stability for HER.

Ultrafine Ni-B nanoparticles for efficient hydrogen evolution reaction

The search for active,stable,and cost-effective electrocatalysts for hydrogen evolution reaction(HER)is desirable,but it remains a great challenge in the overall water splitting.Here,we report the synthesis of nickel boron nanoparticles supported on Vulcan carbon(Ni-B)via a simple,yet scalable,two-step chemical reduction–annealing strategy.The results of the electrochemical measurements suggest that the overpotentials of Ni-B-400 are 114 and 215 mV(in 1 mol L^–1 KOH)at current densities of 10 and 40 mA cm^?2,respectively,indicating an exceedingly good electrocatalytic activity in the HER.More importantly,Ni-B maintains a current density of 7.6 mA cm^-2 at an overpotential of 0.15 V for 20 h in the durability test.The excellent HER activity of Ni-B-400 is derived from the small particle size and the expanded lattice of Ni,which can optimize the hydrogen absorption energy and enhance the electrocatalytic properties.

Three-dimensional lily-like CoNi_2S_4 as an advanced bifunctional electrocatalyst for hydrogen and oxygen evolution reaction

Designing low-cost, highly efficient, and stable bifunctional electrocatalysts for both hydrogen evolution reaction（HER） and oxygen evolution reaction（OER） is of vital significance for water splitting.Herein, three-dimensional lily-like CoNi_2S_4 supported on nickel foam（CoNi_2S_4/Ni） has been fabricated by sulfuration of the Co–Ni precursor. As expected, CoNi_2S_4/Ni possesses such outstanding electrocatalytic properties that it requires an overpotential of only 54 mV at 10 mA cm^（-2） and 328 mV at 100 mA cm^（-2） for HER and OER, respectively. Furthermore, by utilizing the CoNi_2S_4/Ni electrodes as bifunctional electrocatalysts for overall water splitting, a current density of 10 mA cm^（-2） can be obtained at a voltage of only 1.56 V.

Fabrication of triangular Cu_(3)P nanorods on Cu nanosheets as electrocatalyst for boosted electrocatalytic water splitting

Non-precious electro catalysts with high-efficiency, cheapness and stablility are of great significance to replace noble metal electro catalysts in the hydrogen evolution reaction(HER) and oxygen evolution reaction(OER). In this work, triangular Cu@CuO nanorods on Cu nanosheets were fabricated by a novel in-situ oxidation approach using Cu nanosheets as self-template and conductive nano-substrate in an aqueous solution of NaOH/H2O2, and then by lowtemperature phosphorization treatments. The experimental results show that the phosphating temperature has a significant effect on the morphology, composition and number of active sites of Cu@Cu_(3)P nanorods. The Cu@Cu_(3)P-280 electrode exhibits a good HER catalytic activity of achieving a current density of 10 mA/cm^(2) at 252 mV in acid electrolyte. After catalysis for 14 h, the current density can still reach 72% of the initial value. Moreover, the Cu@Cu_(3)P-280 electrode also shows an excellent OER catalytic activity in basic electrolyte, reaching a current density of 10 mA/cm^(2) at the overpotential value of 200 mV. After catalysis for 12 h, the current density remained more than 93% of the initial value. This work provides a theoretical basis for the directional design and preparation of sustainable, low-cost, bifunctional electrocatalytic materials.

Amorphous Ru nanoclusters onto Co‐doped 1D carbon nanocages enables efficient hydrogen evolution catalysis

The development of high-performance electrocatalysts for hydrogen evolution reaction(HER)is of great significance for green,sustainable,and renewable energy conversion.Herein,we report the synthesis of amorphous Ru clusters on Co-doped defect-rich hollow carbon nanocage(a-Ru@Co-DHC)as an efficient electrocatalyst for HER in the basic media.Due to the advantages such as high surface area,rich edge defect,atomic Co doping and amorphous Ru clusters,the as-made a-Ru@Co-DHC displays an efficient HER performance with a near-zero onset overpotential,a low Tafel slope(62 mV dec^(−1)),a low overpotential of 40 mV at 10 mA cm^(−2) and high stability,outperforming the commercial Ru nanocrystal/C,commercial Pt/C,and other reported Ru-based catalysts.This work provides a new insight into designing new metal doped carbon nanocages catalysts supported by amorphous nanoclusters for achieving the enhanced electrocatalysis.

In situ synthesis of a nickel boron oxide/graphdiyne hybrid for enhanced photo/electrocatalytic H_(2) evolution

Developing highly active catalysts for photo/electrocatalytic water splitting is an attractive strategy to produce H2 as a renewable energy source.In this study,a new nickel boron oxide/graphdiyne(NiBi/GDY)hybrid catalyst was prepared by a facile synthetic approach.Benefitting from the strong electron donating ability of graphdiyne,NiBi/GDY showed an optimized electronic structure containing lower valence nickel atoms and demonstrated improved catalytic performance.As expected,NiBi/GDY displayed a high photocatalytic H2 evolution rate of 4.54 mmol g^(-1)h^(-1),2.9 and 4.5 times higher than those of NiBi/graphene and NiBi,respectively.NiBi/GDY also displayed outstanding electrocatalytic H2 evolution activity in 1.0 M KOH solution,with a current density of 400 mA/cm^(2)at an overpotential of 478.0 mV,which is lower than that of commercial Pt/C(505.3 mV@400 mA/cm^(2)).This work demonstrates that GDY is an ideal support for the development of highly active catalysts for photo/electrocatalytic H2 evolution.

Nitrogen‐doped graphene aerogel‐supported ruthenium nanocrystals for pH‐universal hydrogen evolution reaction

The design and synthesis of high‐performance and low‐cost electrocatalysts for the hydrogen evolution reaction(HER),a key half‐reaction in water electrolysis,are essential.Owing to their modest hydrogen adsorption energy,ruthenium(Ru)‐based nanomaterials are considered outstanding candidates to replace the expensive platinum(Pt)‐based HER electrocatalysts.In this study,we developed an adsorption‐pyrolysis method to construct nitrogen(N)‐doped graphene aerogel(N‐GA)‐supported ultrafine Ru nanocrystal(Ru‐NC)nanocomposites(Ru‐NCs/N‐GA).The particle size of the Ru‐NCs and the conductivity of the N‐GA substrate can be controlled by varying the pyrolysis temperature.Optimal experiments reveal revealed that 10 wt%Ru‐NCs/N‐GA nanocomposites require overpotentials of only 52 and 36 mV to achieve a current density of 10 mA cm^(−2) in 1 mol/L HClO4 and 1 mol/L KOH electrolytes for HER,respectively,which is comparable to 20 wt%Pt/C electrocatalyst.Benefiting from the ultrafine size and uniform dispersion of the Ru‐NCs,the synergy between Ru and the highly conductive substrate,and the anchoring effect of the N atom,the Ru‐NCs/N‐GA nanocomposites exhibit excellent activity and durability in the pH‐universal HER,thereby opening a new avenue for the production of commercial HER electrocatalysts.

Sustainable solid-state synthesis of uniformly distributed PdAg alloy nanoparticles for electrocatalytic hydrogen oxidation and evolution

New sustainable syntheses based on solid-state strategies have sparked enormous attention and provided novel routes for the synthesis of supported metallic alloy nanocatalysts(SMACs).Despite considerable recent progress in this field,most of the developed methods suffer from either complex operations or poorly controlled morphology,which seriously limits their practical applications.Here,we have developed a sustainable strategy for the synthesis of PdAg alloy nanoparticles(NPs)with an ultrafine size and good dispersion on various carbon matrices by directly grinding the precursors in an agate mortar at room temperature.Interestingly,no solvents or organic reagents are used in the synthesis procedure.This simple and green synthesis procedure provides alloy NPs with clean surfaces and thus an abundance of accessible active sites.Based on the combination of this property and the synergistic and alloy effects between Pd and Ag atoms,which endow the NPs with high intrinsic activity,the PdAg/C samples exhibit excellent activities as electrocatalysts for both the hydrogen oxidation and evolution reactions(HOR and HER)in a basic medium.Pd9Ag1/C showed the highest activity in the HOR with the largest j0,m value of 26.5 A g Pd^–1 and j0,s value of 0.033 mA cmPd^–2,as well as in the HER,with the lowest overpotential of 68 mV at 10 mA cm^–2.As this synthetic method can be easily adapted to other systems,the present scalable solid-state strategy may open opportunity for the general synthesis of a wide range of well-defined SMACs for diverse applications.

Controlling atomic phosphorous-mounting surfaces of ultrafine W_(2)C nanoislands monodispersed on the carbon frameworks for enhanced hydrogen evolution

Controllably mounting foreign atoms on the surfaces of earth-abundant electrocatalysts strongly improve their surface electronic properties for optimizing the catalytic performance of surficial sites to an unusual level,and provides a good platform to gain deep insights into catalytic reactions.The present work describes,employing ultrafine W2C nanoislands(average size:2.3 nm)monodispersed on the N,P dual-doped carbon frameworks as a model system,how to regulate the atomic phosphorous-mounting effect on the surfaces of W_(2)C to derive an active and stable P-mounting W_(2)C(WCP)catalyst for both acidic and alkaline hydrogen evolution reaction(HER).Since in situ phosphorus substitution into carbon sites of preformed W_(2)C nanoislands gradually proceeds from surfaces to solids,so that using a proper amount of phosphorus sources can readily control the surface mounting level to avoid the mass P-doping into the bulk.By this way,the activity per active site of WCP catalyst with robust stability can be optimized to 0.07 and 0.56 H_(2 )s^(-1) at-200 mV overpotential in acid and base,respectively,which reach up to the several-fold of pure-phase W_(2)C(0.01 and 0.05 H_(2) s^(-1)).Theoretical investigations suggest that compared with solid P doping,the P mounting on W_(2)C surface can more remarkably enhance its metallicity and decrease the hydrogen release barrier.This finding disclosed a key correlation between surface foreign atom-mounting and catalytic activity,and suggested a logical extension to other earth-abundant catalysts for various catalytic reactions.

Highly dispersed few-layer MoS_2 nanosheets on S, N co-doped carbon for electrocatalytic H_2 production

Ultrathin small MoS2nanosheets exhibit a higher electrocatalytic activity for the hydrogen evolution reaction.However,strong interactions between MoS2layers may result in aggregation;together with the low conductivity of MoS2,this may lower its electrocatalytic activity.In this paper we present a method that we developed to directly produce solid S,N co‐doped carbon(SNC)with a graphite structure and multiple surface groups through a hydrothermal route.When Na2MoO4was added to the reaction,polymolybdate could be anchored into the carbon materials via a chemical interaction that helps polymolybdate disperse uniformly into the SNC.After a high temperature treatment,polymolybdate transformed into MoS2at800°C for6h in a N2atmosphere at a heating rate of5°C/min,owing to S2?being released from the SNC during the treatment(denoted as MoS2/SNC‐800‐6h).The SNC effectively prevents MoS2from aggregating into large particles,and we successfully prepared highly dispersed MoS2in the SNC matrix.Electrochemical characterizations indicate that MoS2/SNC‐900‐12h exhibits a low onset potential of115mV and a low overpotential of237mV at a current density of10mA/cm2.Furthermore,MoS2/SNC‐900‐12h also had an excellent stability with only^2.6%decay at a current density of10mA/cm2after5000test cycles.

Proton reduction in the presence of oxygen by iron porphyrin enabled with 2nd sphere redox active ferrocenes

Hydrogen evolution in the presence of atmospheric level of oxygen is a significant barrier in the quest for an alternative,sustainable and green source of energy to counter the depleting fossil fuel sources and increasing global warming due to fossil fuel burning.Oxygen reduction is thermodynamically more favourable than proton reduction and it often produces reactive oxygenated species upon partial reduction which deactivates the catalyst.Thus,catalyst development is required for efficient proton reduction in the presence of oxygen.Here,we demonstrate an iron porphyrin having triazole containing 2nd sphere hydrogen bonding residues appended with redox active ferrocene moieties(α4-Tetra-2-(3-ferrocenyl-1,2,3-triazolyl)phenylporphyrin(FeFc4))as a bifunctional catalyst for fast and selective oxygen reduction to water and thus,preventing the proton reduction by the same catalyst from oxidative stress.Fe(0)is the active species for proton reduction in these iron porphyrin class of complexes and it is observed that the kinetics of proton reduction at Fe(0)state occurs at much faster rate than O2 reduction and thus,paving the way for selective proton reduction in the presence of oxygen.