MoS2/石墨烯/泡沫炭复合材料的析氢性能

以包覆石墨烯的炭化三聚氰胺泡沫作为支撑,通过水热法在三维泡沫炭上原位生长二硫化钼(MoS2)纳米片,合成出一系列的MoS2/石墨烯/泡沫炭复合材料.经XRD和TEM表征,拥有三维网络结构的炭基骨架被厚度为15～20 nm的MoS2纳米片均匀包裹.石墨烯包覆量对析氢性能影响很大,包覆浓度25 mg L-1的R-&CMMS...     

共掺杂三维石墨烯的制备及其电催化析氢性能的研究

选择天然石墨鳞片为原料,采用改进的Hummers法制备出氧化石墨(GO),再以硫脲、硫酸亚铁和氯化镍为改性剂,利用化学还原法和自组装法制备了氮、硫、铁、镍共掺杂三维石墨烯电极材料。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线能谱(EDS)等测试手段对材料进行分析表征,研究了不同因素对其析氢反应活性(HER)的影响,并通过均匀试验设计确定了制备的最佳工艺条件。结果表明:所制备的电极材料具有丰富的孔结构和完整的三维结构,石墨烯片层间距为0.3734 nm,并且无明显垛叠团聚,在酸性条件下显示出较高的HER活性,在电流密度为10 mA/cm2时,析氢过电位为-158 mV,塔菲尔(Tafel)斜率为74.33 mV/dec。     

MoS2/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。     

水热法制备镍负载硫磷双掺杂石墨烯电极及其电催化析氢性能研究

设计一种高活性、高稳定性的非贵金属基催化剂,对电催化析氢的应用具有重要意义.以硫酸和植酸为硫磷掺杂剂,采用水热法合成了硫磷共掺杂石墨烯(SPG);随后,采用简单的醇热法制备了直接生长在SPG上的Ni基纳米材料(Ni/SPG).制备的Ni/SPG电催化剂表现出杰出的析氢性能,其阻抗极低(0.48Ω),电化学活性表面积极好...     

复合电沉积制备（Ni-Mo）-TiO2电极及其电催化析氢性能

为开发新型廉价高效的析氢材料,用恒电流复合电沉积方法制备了(Ni-Mo)-TiO2复合电极,讨论了TiO2悬浮量和电沉积时间对电极催化析氢性能的影响.用XRD和SEM对电极的晶体结构和表面形貌进行了表征,以稳态极化曲线对电极的催化析氢特性进行了评价.结果表明,(Ni-Mo)-TiO2电极是纳米TiO2粒子相和纳米晶Ni-Mo固溶体相构成的复合电极.电极具有较高的催化析氢活性.在25℃、0.5mol.dm-3H2SO4溶液中其表观交换电流密度是Ni-Mo合金电极的2.6倍,是Ni电极的60倍.在电流密度为100mA·cm-2时,电极电势相对于Ni-Mo电极正移了120mV,相对于Ni电极正移了542mV.催化活性的提高源于反应机理的改变,表观活化吉布斯自由能相对于Ni-Mo合金电极降低了24.48kJ·mol-1.     

NiS2@MoS2/CC纳米复合材料的制备及其电催化析氢性能的研究

电解水产氢是近来研究的热点,电极催化材料是影响析氢反应的重要因素.通过两步水热法,成功在碳布上合成了NiS2@MoS2三维异质结构复合催化剂(NiS2@MoS2/CC).在碳布上垂直排列的NiS2纳米片为MoS2提供了良好的支撑,在暴露更多边缘活性位点的同时,也为析氢反应提供了快速的物质传输通道.合理的界面设计促使Ni...     

Ag2S修饰TiO2纳米管复合电极的制备及其析氢性能研究

以硫化钠和硝酸银为原料,采用了化学浴沉积法将Ag₂S沉积在高度有序TiO₂纳米管（TNTs）上制备出Ag₂S/TNTs析氢电极。采用扫描电子显微镜（SEM）、X射线衍射分析（XRD）、X射线光电子能谱分析（XPS）对电极进行表征,结果显示Ag₂S颗粒均匀的沉积在TiO₂纳米管表面,且没有破坏纳米管原有的形态结构。在0.5 mol/L H₂SO₄条件下,通过线性扫描伏安法（LSV）、塔菲尔曲线（Tafel）、双电层电容和电化学阻抗谱（EIS）等电化学测试分析了不同Ag₂S沉积圈数所得的复合电极的析氢性能。与TNTs相比,Ag₂S/TNTs显示出更优异的析氢性能。Ag₂S沉积圈数为9圈时制备出的复合电极在10 mA/cm²电流密度时,过电位达到了288.14 mV,Tafel斜率为61.8 mV/dec,双电层电容分别为54.7 mF/cm²,传荷内阻降低到0.7Ω/cm²。     

FeOOH-Ni（OH）2复合材料的制备及其电催化析氧性能

以碳纤维布（CFC）为基底,通过两步法（恒电流电沉积法、溶剂热法）成功制备了FeOOH-Ni（OH）₂复合材料。与FeOOH和Ni（OH）₂相比,该FeOOH-Ni（OH）₂复合材料作为电催化剂时,电催化析氧反应（OER）活性显著提高。在1 mol/L KOH电解质溶液中,达到10 mA·cm-2电流密度时所需要的过电位仅为270 mV,Tafel斜率为78 mV/dec,电化学阻抗谱进一步揭示了电解过程中良好的动力学特性。FeOOHNi（OH）₂复合材料在碱性介质中具有优异的稳定性,其在高电流密度下（50 mA·cm-2）的过电势经过连续24 h的测试之后几乎没有发生明显变化。FeOOH和Ni（OH）₂之间的强电子相互作用和协同效应有效提高了电导性,促进了电荷转移;此外,这种核壳结构有效增强了电催化活性面积,进而增强了其电催化析氧性能。     

多孔碳负载钌单原子和钌纳米团簇催化剂用于高效析氢反应

高效析氢反应(HER)电催化剂的制备对氢能的大规模推广具有重大的意义。本文以羧甲基纤维素钠(CMC-Na)和RuCl₃为原料,利用Ru离子与CMC-Na在溶液中配位制备了Ru-CMC-Na水凝胶,随后通过冷冻干燥、高温退火和酸洗制备了多孔碳负载Ru单原子和Ru纳米团簇的催化剂Ru _SA+NC/C-2。催化剂Ru_SA+NC/C-2在酸性和碱性电解质中都具有优异的HER活性和稳定性,达到10 mA·cm^-2电流密度,所需过电位分别20 mV和23 mV,经过12 h的恒电位测试其活性未见明显衰减。催化剂Ru_SA+NC/C-2中Ru的含量为5.52wt%,在1 mol/L KOH电解质中,过电位为0.05 V时,催化剂的质量活性是商业Pt/C的5.8倍。通过对催化剂Ru_SA+NC/C-2的物理表征测试发现,催化剂Ru_SA+NC/C-2的多孔结构和大比表面积,可以暴露更多的活性位点。Ru单原子与Ru纳米团簇结构提高了Ru原子的利用率。通过XP...     

纳米TiO2修饰 Ni-W-P电极的制备及其光电催化析氢性能

在Cu基体上电沉积Ni-W-P合金后,通过溶胶-凝胶法制备了纳米TiO2修饰Ni-W-P合金电极．利用扫描电子显微镜（SEM）、X射线衍射（XRD）、阴极极化曲线测试了TiO2／Ni-W-P电极的表面形貌、结构及催化析氢性能,考察了烧结温度、TiO2膜层厚度对电极结构和性能的影响．实验结果表明：550℃下烧结1h、拉膜15次制备的TiO2／Ni-W-P电极光电催化析氢性能最佳,500W碘钨灯照射下析氢过电位减小约140mV;此时TiO2为锐态矿型和金红石型混晶结构,平均晶粒尺寸约7nm．     

Defect-rich MoS<Subscript>2</Subscript> nanowall catalyst for efficient hydrogen evolution reaction

Designing efficient electrocatalysts for the hydrogen evolution reaction (HER) has attracted substantial attention owing to the urgent demand for clean energy to face the energy crisis and subsequent environmental issues in the near future.Among the large variety of HER catalysts,molybdenum disulfide (MoS2) has been regarded as the most famous catalyst owing to its abundance,low price,high efficiency,and definite catalytic mechanism.In this study,defect-engineered MoS2 nanowall (NW) catalysts with controllable thickness were fabricated and exhibited a significantly enhanced HER performance.Benefiting from the highly exposed active edge sites and the rough surface accompanied by the robust NW structure,the defect-rich MoS2 NW catalyst with an optimized thickness showed an ultralow onset overpotential of 85 mV,a high current density of 310.6 mA·cm-2 at η =300 mV,and a low potential of 95 mV to drive a 10 mA.cm-2 cathodic current.Additionally,excellent electrochemical stability was realized,making this freestanding NW catalyst a promising candidate for practical water splitting and hydrogen production.     

A stepwise-designed Rh-Au-Si nanocomposite that surpasses Pt/C hydrogen evolution activity at high overpotentials

Hydrogen evolution by electrocatalysis is an attractive method of supplying clean energy.However,it is challenging to find cheap and efficient alternatives to rare and expensive platinum based catalysts.Pt provides the best hydrogen evolution performance,because it optimally balances the free energies of adsorption and desorption.Appropriate control of these quantities is essential for producing an efficient electrocatalyst.We demonstrate,based on first principles calculations,a stepwise designed Rh-Au-Si ternary catalyst,in which adsorption (the Volmer reaction) and desorption (the Heyrovsky reaction) take place on Rh and Si surfaces,respectively.The intermediate Au surface plays a vital role by promoting hydrogen diffusion from the Rh to the Si surface.Theoretical predictions have been explored extensively and verified by experimental observations.The optimized catalyst (Rh-Au-SiNW-2) has a composition of 2.2∶28.5∶69.3 (Rh∶Au∶Si mass ratio) and exhibits a Tafel slope of 24.0 mV·dec-1.Its electrocatalytic activity surpasses that of a commercial 40 wt.％ Pt/C catalyst at overpotentials above 0.19 V by exhibiting a current density of greater than 108 mA·cm-2.At 0.3 V overpotential,the turnover frequency of Rh-Au-SiNW-2 is 10.8 times greater than that of 40 wt.％ Pt/C.These properties may open new directions in the stepwise design of highly efficient catalysts for the hydrogen evolution reaction (HER).     

Nitrogen-doped graphene microtubes with opened inner voids: Highly efficient metal-free electrocatalysts for alkaline hydrogen evolution reaction

A facile method was developed to fabricate nitrogen-doped graphene microtubes (N-GMT) with ultra-thin walls of 1–4 nm and large inner voids of 1–2 μm. The successful introduction of nitrogen dopants afforded N-GMT more active sites for significantly enhanced hydrogen evolution reaction (HER) activity, achieving a current density of 10 mA·cm^–2 at overpotentials of 0.464 and 0.426 V vs. RHE in 0.1 and 6 M KOH solution, respectively. This HER performance surpassed that of the best metal-free catalyst reported in basic solution, further illustrating the great potential of N-GMT as an efficient HER catalyst for real applications in water splitting and chlor-alkali processes.

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MoS2/Co9S8/MoC heterostructure connected by carbon nanotubes as electrocatalyst for efficient hydrogen evolution reaction

High-performance multifunctional materials for water splitting driven by low voltage are crucial for hydrogen evolution reaction (HER),but developing such materials is challenging.Herein,a simple strategy was designed to build a MoS2/Co9S8/MoC@CNT-N (MCM@CNT-N) heterostructure with a large number of interfaces.Regarding the HER,the synthesized MCM@CNT-N heterostructure catalyst showed high efficiency and stable electrocatalytic performance,with a low overpotential of 174.2 mV and a small Tafel slope of 84.7 mV dec-1 at a current density of 10 mAcm-2 in 0.5 M H2SO4.In addition to the function of heterojunctions,the excellent activity is also attributed to the introduction of Co and N atoms and the formation of carbon nanotubes.This work provides a new approach to build efficient and low-cost electrocatalysts for electrochemical reactions.     

氮掺杂碳纳米纤维包覆超细碳化钼/氮化钼异质结构用于碱性条件下电催化析氢

高效非贵金属催化剂对于推进析氢反应(HER)的大规模工业化至关重要.碳化钼(Mo₂C)因其类似铂的能带密度和优良的中间产物吸附特性,有望替代贵金属基材料成为具有前景的催化剂.然而,它在常规制备过程中存在严重的晶体过度生长和团聚问题,导致催化效率低.本研究利用三聚氰胺辅助法制备了含有丰富表面和界面的超细碳化钼/氮化钼(Mo₂C/Mo₂N)异质结构,并同时将其嵌入到氮掺杂碳纳米纤维(CNFs)中.Mo₂C/Mo₂N异质结构的协同作用与超细纳米晶表面暴露的丰富活性位点共同提高了电催化活性,而氮掺杂碳纳米纤维框架保证了快速的电荷转移和良好的结构稳定性.此外,原位形成的Mo₂C/Mo₂N晶体与碳基质之间存在较强的界面耦合作用,进一步提高了电子电导率和电催化活性.得益于这些优势,Mo₂C/Mo₂N@N-CNFs在碱性溶液中表现出优异的电催化析氢性能,在电流密度10 mV cm^-2时具有75 mV的低过电势,优于单相Mo₂C@N-CNFs对比样以及近期报道的Mo₂C/Mo₂N基催化剂.这个合成方法集成了异质结构、纳米化和碳修饰策略,为设计高效率电催化材料提供了新的参考.     

Wet-chemistry synthesis of cobalt carbide nanoparticles as highly active and stable electrocatalyst for hydrogen evolution reaction

Transition metal carbide (TMC) nanomaterials are promising alternatives to Pt,and are widely used as heterogeneous electrocatalysts for the electrochemical hydrogen evolution reaction (HER).In this work,a bromide-induced wet-chemistry strategy to synthesize Co2C nanopartides (NPs) was developed.Such NPs exhibited high electrocatalytic activity (η =181 mV for j =-10 mA.cm-2) and long-term stability (no obvious performance decrease after 4,000 cycles) for the HER.This study will pave the way for the design and fabrication of TMC NPs via a wetchemistry method,and will have significant impacts on broader areas such as nanocatalysis and energy conversion.