Tuning Active Metal Atomic Spacing by Filling of Light Atoms and Resulting Reversed Hydrogen Adsorption-Distance Relationship for Efficient Catalysis

Precisely tuning the spacing of the active centers on the atomic scale is of great significance to improve the catalytic activity and deepen the understanding of the catalytic mechanism,but still remains a challenge.Here,we develop a strategy to dilute catalytically active metal interatomic spacing(d_(M-M))with light atoms and discover the unusual adsorption patterns.For example,by elevating the content of boron as interstitial atoms,the atomic spacing of osmium(d_(Os-Os))gradually increases from 2.73 to 2.96?.More importantly,we find that,with the increase in dOs-Os,the hydrogen adsorption-distance relationship is reversed via downshifting d-band states,which breaks the traditional cognition,thereby optimizing the H adsorption and H_2O dissociation on the electrode surface during the catalytic process;this finally leads to a nearly linear increase in hydrogen evolution reaction activity.Namely,the maximum dOs-Os of 2.96?presents the optimal HER activity(8 mV@10 mA cm^(-2))in alkaline media as well as suppressed O adsorption and thus promoted stability.It is believed that this novel atomic-level distance modulation strategy of catalytic sites and the reversed hydrogen adsorption-distance relationship can shew new insights for optimal design of highly efficient catalysts.

Enhanced hydrogen evolution from the face-sharing[RuO6]octahedral motif

Hampered by the ambiguous mechanism of hydrogen evolution reaction(HER)in basic media,the exploration of highly efficient catalytically active sites for alkaline HER is of significance.Herein,a metal oxide Sr_(4)Ru_(2)O_(9)engineering a face-sharing[RuO_(6)]octahedra motif was synthesized through the solid-state method,and served as HER electrocatalyst.Benefited from the Ru-Ru metallic bonding crossing the common plane,the H*adsorption and reaction energy barriers were optimized.Sr_(4)Ru_(2)O_(9)only required an ultra-small overpotential(η10)of 28 m V at a current density of 10 mA cm^(-2) for HER in 1.0 M KOH with an exceptional stability(180 hours),outperforming the commercial Pt/C(η10=38 mV).These findings suggest a fresh insight in designing novel active sites for electrocatalysis.

Pseudobrookite based heterostructures for efficient electrocatalytic hydrogen evolution

Synthesis of ultrathin heterostructures has received much attention in the recent past due to their unique physical and chemical properties.In this work,we report the synthesis of Fe_(2)TiO_(5)–TiO_(2)heterostructures using a simple hydrothermal technique employing natural ilmenite as the source.Hierarchically arranged nanostructures with interconnected nano-petals of thickness around 50 nm are obtained.The electrocatalytic properties of the synthesized Fe_(2)TiO_(5)–TiO_(2)heterostructures are enhanced following the cathodization technique.The observed enhancement in the synthesized materials’electrocatalytic property can be attributed to the defect-rich Fe_(2-x)TiO_(5-x)-TiO_(2-x)heterostructures.The current approach and technique discussed in this work offer a simple method to synthesize a nanostructured heterostructure material and create defects for enhancing electrocatalytic activity.

Chalcogen-dependent catalytic properties of RuX2 (X = S/Se/Te) nanoparticles decorated carbon nanofibers for hydrogen evolution in acidic and alkaline media

Transition metal dichalcogenides(TMDs),with the general formula MX_(2)(M=Mo/W/Fe/Co/Ni,etc.;X=S/Se/Te),have attracted extensive research interests for hydrogen evolution reaction(HER).Compared with numerous studies on noble-metal-free TMDs,the chalcogen-dependent HER catalytic properties of noble-metal-based TMDs are lack of sufficient research attention.Herein,a facile electrospinning-assisted synthetic strategy is proposed to synthesize ruthenium dichalcogenides(RuX_(2),X=S/Se/Te)nanoparticles decorated carbon nanofibers(CNFs).Benefiting from the identical nanofibrous morphology and exposed crystal planes of RuX_(2)(111),the catalytic activities of RuX_(2)@CNFs samples were investigated and compared in a fair and direct manner.Detailed electrochemical measurements coupled with density functional theory calculations were carried out to probe their intrinsic HER catalytic activities,resulting in the catalytic activity order of RuS_(2)@CNFs>RuSe_(2)@CNFs>RuTe_(2)@CNFs in acidic media and that of RuS_(2)@CNFs>RuTe_(2)@CNFs>RuSe_(2)@CNFs in alkaline media.The superior catalytic performance of RuS_(2)@CNFs mainly stems from the relative lower HER energy barriers and thereby the higher intrinsic catalytic activity of RuS_(2)(111),leading to ultralow overpotentials of 44 and 9 mV at 10 mA·cm^(-2) in acidic and alkaline media,respectively.RuSe_(2)(111)is endowed with the more optimized Gibbs free energy of hydrogen adsorption(ΔGH*)than RuTe_(2)(111),but RuTe_(2)(111)shows enhanced catalytic property for H_(2)O dissociation and OH-desorption than RuSe_(2)(111),therefore,resulting in the altered catalytic activity sequences for RuSe_(2) and RuTe_(2) in acidic and alkaline media.

Highly reversible lead-carbon battery anode with lead grafting on thecarbon surface

A novel C/Pb composite has been successfully prepared by electmless plating to reduce the hydrogenevolution and achieve the high reversibility of the anode of lead-carbon battery （LCB）. The depositedlead on the surface of C/Pb composite was found to be uniform and adherent to carbon surface. Becauselead has been stuck on the surface of C/Pb composite, the embedded structure suppresses the hydrogenevolution of lead-carbon anode and strengthens the connection between carbon additive and sponge lead.Compared with the blank anode, the lead-carbon anode with C/Pb composite displays excellent charge-discharge reversibility, which is attributed to the good connection between carbon additives and leadthat has been stuck on the surface of C/Pb composite during the preparation process. The addition of CIPb composite maintains a solid anode structure with high specific surface area and power volume, andthereby, it plays a significant role in the highly reversible lead-carbon anode.

A new method to improve surface morphology of Ni-Fe-Mo-Co alloy electrode and its catalytic activity for HER

A new pretreatment method has been developed to improve the catalytic activity of the Ni-Fe-Mo-Co alloy electrode for hydrogen evolution reaction （HER）. The procedure involves pre-electrolyzing the Ni-Fe-Mo-Co alloy electrode in 30% KOH solution containing 10% potassium sodium tartrate at 70℃ for 2 h, until some of the Mo and Fe elements are leached out. The surface morphology of the Ni-Fe-Mo-Co alloy demonstrates a unique hive-like structure after the pre- treatment, which has the pore size in a nanometer range （about 50 nm）, a very large real surface area, and good stability. The results of the electrochemical studies show that compared to other similar electrode materials and the treated Ni-Fe-Mo-Co electrode by leaching method, the pre-treated Ni-Fe-Mo-Co electrode has a much lower overpotential and much higher exchange current density for HER. In addition, a long-term continuous electrolysis test with a current interruption shows that the Ni-Fe-Mo-Co alloy has excellent catalytic stability.

Surface structure and catalytic activity of electrodeposited Ni-Fe-Co-Mo alloy electrode by partially leaching Mo and Fe

Ni-Fe-Mo-Co alloy electrode was prepared in a citrate solution by electrodeposition, and then Mo and Fe were partially leached out from the electrode in 30% KOH solution. The unique surface micromorphology of a hive-like structure was obtained with an average pore size of about 50 nm. The electrode has a very large real surface area and a stable structure. The effects of sodium molybdate concentration on the composition, surface morphology, and structure of electrodes were analyzed by EDS, SEM and XRD. The polarization curves of the different electrodes show that the catalytic activity of electrodes is strongly correlated with the mole fraction of alloy elements (Ni, Fe, Mo, Co), and the addition of cobalt element to Ni-Fe-Mo alloy improves the catalytic activity. The Ni35.63Fe24.67Mo23.52Co16.18 electrode has the best activity for hydrogen evolution reaction(HER), with an over-potential of 66.2 mV, in 30% KOH at 80 ℃ and 200 mA/cm2. The alloy maintains its good catalytic activity for HER during continuous or intermittent electrolysis. Its electrochemical activity and catalytic stability are much higher than the other iron-group with Mo alloy electrodes.

电解水析氢反应磷化钴异质结催化剂的研究进展

氢气(H_(2))作为一种可再生的绿色能源,在解决环境和化石能源紧缺问题受到了广泛关注。发展高效、稳定和低成本的析氢反应(Hydrogen evolution reaction,HER)电催化剂是目前氢能大规模利用面临的主要挑战之一。磷化钴(CoP)由于其类金属特性及耐酸碱腐蚀等优点,在电催化HER领域中受到广泛研究。本文以CoP与其它纳米材料形成的异质结所产生的不同效应提升HER活性为出发点,首先介绍了CoP异质结作为电催化剂用于电催化HER的优势及其所面临的挑战,其次从CoP异质结产生的不同效应在电催化HER发挥的作用等方面进行了系统的论述,最后总结和展望了CoP异质结在电催化HER方向的发展前景。

Zn掺杂1T/2H-Zn@MoS_(2)复合材料的制备及其电催化析氢反应性能

开发原料丰富、价格低廉且催化性能优异的析氢反应(HER)催化剂代替Pt基催化剂,对于水分解制氢产业具有非常重要的意义。以廉价的四水合钼酸铵((NH_(4))_(6)Mo_(7)O_(24)·4H_(2)O)、硫脲(CH_(4)N_(2)S)、六水合硝酸锌(Zn(NO_(3))_(2)·6H_(2)O)以及葡萄糖(C_(6)H_(12)O_(6))为原料,采用常规的水热法成功地制备了具有片状形貌的Zn掺杂1T/2H-Zn@MoS_(2)复合物。采用了X射线衍射仪(XRD)、Raman光谱仪、扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)对制备的样品进行了详细的表征分析。实验结果表明,Zn掺杂量能够影响MoS_(2)相结构的变化,当Zn与Mo的物质的量之比为1∶500时,制备的MoS_(2)中无ZnS相,而此时Zn原子取代了MoS_(2)中Mo原子的位置。Zn原子的取代使MoS_(2)产生了结构缺陷,活化了1T-MoS_(2)面内活性位点,提高了活性位点密度。实验结果也表明,Zn原子作为电子给体,促使了1T/2H-Zn@MoS_(2)中MoS_(2)的2H相向1T相的转变,使得1T相的占比率提高到了38.6%。因此,1T/2H-Zn@MoS_(2)的HER性能得到了显著增强,在质量浓度0.5 mol/L的H_(2)SO_(4)溶液中,仅需178.6 mV的过电位就可达到10 mA·cm^(-2)的电流密度,并展现了良好的稳定性。

Surface/Interface Engineering of Hierarchical MoO_(2)/MoNi_(4)@Ru/RuO_(2)Heterogeneous Nanosheet Arrays for Alkaline Water Electrolysis with Fast Kinetics

Realizing the hydrogen economy by water electrolysis is an attractive approach for hydrogen production,while the efficient and stable bifunctional catalysts under high current densities are the bottleneck that limits the half-cell reactions of water splitting.Here,we propose an approach of hydrothermal and thermal annealing methods for robust MoO_(2)/MoNi_(4)@Ru/RuO_(2) heterogeneous cuboid array electrocatalyst with multiplying surface-active sites by depositing a monolayer amount of Ru.Benefiting from abundant MoO_(2)/MoNi_(4)@Ru/RuO_(2)heterointerfaces,MoO_(2)/MoNi_(4)@Ru/RuO_(2) heterogeneous cuboid array electrocatalysts effectively drive the alkaline water splitting with superior hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)performances.The synthesized MoO_(2)/MoNi_(4)@Ru/RuO_(2) has high HER activity,which realizes the working overpotentials of 48 mV at 50 mA·cm^(-2),further achieving overpotentials of 230 mv for industry-level 1000 mA·cm^(-2) in alkaline water electrolysis.Moreover,it also showed an enhanced OER activity than commercial RuO_(2) with a small overpotential of 280 mV at 200 mA·cm^(-2) in alkaline media.When building an electrolyzer with electrodes of(-)MoO_(2)/MoNi_(4)@Ru/RuO_(2)IIMo02/MoNig@Ru/RuO_(2)(+),a cell voltage of 1.63 V and 1.75 V is just required to support the current density of 200 mA·cm^(-2) and 500 mA-cm^(-2) in alkaline water electrolysis,much lower than that of the electrolyzer of(-)Pt/CIIRuO_(2)(+).This work demonstrates that MoO_(2)/MoNig@Ru/RuO_(2) heterogeneous nanosheet arrays are promising candidates for industrial water electrolysis applications,providing a possibility for the exploration of water electrolysis with a large currentdensity.

Ni-WC复合电极在弱酸性介质中的析氢催化性能

Ni-WC composite coating was obtained by using composite electrodeposition technique. The behavior of Ni-WC composite coating used as cathode material for hydro gen evolution reaction (HER) in a medium of 0.1 mol .L-1H2SO4+0.5mol.L-1 Na2SO4 was inverstigated. The experimental results show that the catalytic activity of Ni-WC composite electrode for HER in weak acidic medium is appearently higher than that of the electrode plated with Ni and is increased with the increasing of WC content in the coating. As compared with Ni plated electrode, the increase in catalytic activity of the composite electrode for HER should be attributed to the dispersion of WC particles in the Ni deposit, since the mechanism of HER for the two kinds of electrodes is the same.Owing to the incorporation of WC particles in Ni deposit, the standard activation free enthalpy for HER is decreased, and the defects and dislocations in the crystal sturcture of the composite coating are increased. This is equivalent to the addition of catalysis accelerator WC in the catalyst Ni.

NiCu双金属电极电催化析氢

采用恒电流共沉积方法制备了具有纳米结构的NiCu双金属电极。采用线性扫描、塔菲尔曲线、电流时间曲线及电化学阻抗谱对NiCu双金属电极电催化析氢的性能进行了测试;并且还利用X射线衍射(XRD)、扫描电子显微镜(SEM)和循环伏安测试手段对其组成、相结构和表面形貌进行了表征和分析。实验结果表明,NiCu双金属电极的电催化析氢性能明显优于Ni电极或Cu电极,这可能与Cu和Ni的协同作用有关。在所研究的NiCu双金属电极中,NiCu0.04具有较好的电化学析氢活性,这主要与其电化学反应电阻较小和比表面积较大有关。

电沉积镍-钼-钴泡沫合金析氢电极的工艺研究

以聚氨酯海绵为基体,通过导电化处理、电沉积Ni–Mo–Co合金以及热分解处理工艺,制备了Ni–Mo–Co泡沫合金。研究了七水合硫酸钴和二水合钼酸钠用量、电流密度、温度等电沉积工艺参数对合金析氢性能的影响。结果表明,在七水合硫酸钴用量为14g/L,二水合钼酸钠用量为10g/L,温度为35°C,电流密度为8A/dm2的条件下制备的泡沫合金有最高的析氢活性,具有很大的比表面积。扫描电镜观察显示,制备的Ni–Mo–Co合金为三维网状结构,合金骨架有大量的微裂纹,表面为均匀致密的球状颗粒。

电镀Ni-Co合金及其电催化性能的研究

研究了以钛和铁为基体的Ni-Co合金电镀，镀层紧密细致、结合力强、耐高温、耐腐蚀、硬度大，并具有优良的电催化性能。

离子束修饰提高钛阴极析氢活性

研究了双重离子注入Ｗ＋／Ｎｉ＋，Ｗ＋／Ｍｏ＋及溅射Ｆｅ后再单离子注入Ｃｏ＋或Ｗ＋等离子束修饰的钛电极在１ＮＨ２ＳＯ４中的析氢电催化性能．结果表明：与纯钛电极相比，离子束修饰电极的催化析氢活性得到显著改善．其中，注Ｗ＋／Ｎｉ＋电极的析氢过电位降低３００ｍＶ．用ＸＰＳ和ＡＥＳ能谱分析了离子束修饰电极的表面元素及相结构，讨论了修饰电极催化析氢机理．

高析氢催化活性和稳定性的纳米晶Ni-Fe-Mo-Co合金

在酸性柠檬酸盐-氯化物体系中电沉积得到铁族金属与钼多元合金,通过SEM、XRD和EDS对合金的表面形貌、微观结构和组成进行分析,结果表明Ni-Fe-Mo-Co电极为纳米晶,晶粒尺寸为3.7nm;电解后电极表面呈现"蜂窝"型网孔结构,平均孔径约50nm,具有很大的真实表面积和机械稳定性。通过比较不同的铁族金属与钼合金电极在30%KOH溶液中的催化性能,表明在Ni-Fe-Mo三元合金中引入Co能进一步提高合金的催化活性。纳米晶Ni-Fe-Mo-Co合金电极在80℃和200mA/cm2时,过电位为66.2mV,与其它铁族金属与钼合金电极相比较,其显示出更高的催化活性。长期和间断电解实验,说明纳米晶Ni-Fe-Mo-Co合金电极具有良好的催化稳定性能。

钌镍氧化物活性阴极的研究

本文研究了钌镍氧化物活性阴极的制备工艺条件对电性能的影响，以及钌镍氧化物活性阴极在碱溶液中的析氢反应（ＨＥＲ），测定了阴极析氢反应（ＨＥＲ）的动力学参数，提出了合理的阴极析氢反应（ＨＥＲ）机理。最后，研究了钌镍氧化物活性阴极的失活和修复。

水溶液电解新阴极材料Ni-Co-S-Mo合金的研究

多年来，人们对催化析氢阴极材料已进行了不少研究［１～１２］．其中Ｐｔ、Ｐｄ等贵金属价格昂贵，不如ＲａｎｅｙＮｉ和过渡金属容易在实际生产中应用［４～１２］．由于ＲａｎｅｙＮｉ的制备还要将合金中的Ａｌ或Ｚｎ溶出，形成多孔结构，故其机械强度较差．在过渡...

电沉积Ni–Ru合金及其结构和性能研究

在（25±2）°C下,从含有50g/LRuCl3·nH2O、30.0g/L乙酸钠、30.0g/L二水合柠檬酸钠和15.0-50.0g/LNiSO4·6H2O的溶液（pH3.0）中,以10-90mA/cm2在铜基底上电沉积制备了Ru含量为5%-70%（原子分数）的Ni–Ru合金。采用X射线衍射（XRD）、扫描电子显微镜（SEM）和电化学方法,研究了镀液中NiSO4质量浓度和电流密度对沉积层组成、表面形貌、结构及电催化析氢活性的影响。结果表明,溶液中Ru优先析出并能促进Ni的沉积,镀层中Ru含量随着镀液中Ni2＋质量浓度的提高而降低,低电流密度有利于获得Ru含量高的镀层。随着镀液中Ni2＋质量浓度的降低或电流密度的提高,镀层表面形貌由较为平整、均匀变为多孔的颗粒状。镀层主要呈现面心立方Ni结构特征,且晶粒尺寸随镀层中Ru含量的增加而变小。Ni–Ru合金电极的析氢活性优于纯Ni,当镀层的Ru原子分数超过15%时,其析氢活性与纯Ru电极接近。

镍-硫化镍复合物析氢活性阴极的研究

对用电沉积法获得镍-硫化镍复合沉积层作碱性溶液中析氢活性阴极材料的可能性进行了研究。实验结果发现,可直接在水溶液中于阴极上形成含硫化镍的镍基复合物沉积层、含硫约12.5wt%的复合物电极,其析氢反应催化活性比镀镍电极提高了10多倍。复合电极析氩催化活性的提高、应归因于电极中NiS和微晶多缺陷多位错结构的存在,导致氢析出反应机理的改变和反应活化能的降低。