RuCs/Mo2C纳米棒制备及电催化析氢的研究

Mo₂C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/Mo₂C)负载Mo₂C纳米棒复合材料。研究表明,Ru Cs/Mo₂C(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/Mo₂C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。     

金属有机骨架衍生的自支撑Co9S8/Ni3S2纳米片阵列用于高效电催化分解水性能研究

采用简单、可控的阳离子交换法和水热法在导电基底上成功构筑了具有自支撑纳米片阵列结构的Co_9S_8/Ni_3S_2电催化剂,在碱性电解液(1 mol/L KOH)中,采用三电极体系分别研究了Co_9S_8/Ni_3S_2的电催化析氧和析氢性能。在析氧性能测试中,Co_9S_8/Ni_3S_2/NF电催化剂获取50、100 mA/cm~2的催化电流密度所需要的过电位仅为230、280 mV。而在析氢性能测试中,Co_9S_8/Ni_3S_2/NF电催化剂获取-100 mA/cm~2的催化析氢电流密度所需的过电位仅为129 mV,同时该催化剂表现出了优异的电催化稳定性,其优异的电催化性能归因于其自支撑纳米片阵列结构,可提供更多的活性位点。     

Pd/WS2二维复合材料的制备及电解水制氢性能研究

首先通过锂离子插层制备了薄层WS_2纳米片,并采用软模板法在纳米片上负载了Pd纳米颗粒,得到Pd/WS_2复合材料。X射线衍射光谱(XRD)和透射电子显微镜(TEM)的结果表明Pd颗粒均匀地负载在了WS_2纳米片上。随后在H_2SO_4水溶液中对该复合材料进行电解水析氢性能测试,线性扫描伏安法(LSV)结果表明:复合材料的析氢起始电位为155 mV,塔菲尔斜率为121.79 mV·dec~(-1),总体催化性能相比于单纯的WS_2纳米片和Pd金属颗粒有很大的改善,也优于当前商用的Pd/C催化剂。采用循环伏安法(CV)测试其稳定性,结果表明Pd/WS_2复合物电极具有优良的电催化析氢稳定性。     

碳化钼/碳纳米片复合材料的制备及析氢性能研究

为了解决Pt基催化剂成本较高的问题,使用电弧放电和高温碳化两步法制备了一种碳纳米片负载碳化钼纳米颗粒的非贵金属催化剂。通过X-射线粉末衍射仪(XRD)、透射电子显微镜(TEM)对催化剂的晶体结构、形貌、碳化钼颗粒尺寸进行了表征分析。结果表明,700℃碳化得到的碳化钼/碳纳米片复合催化剂(Mo_2C/CNS)在酸性电解质溶液中表现出优异的析氢性能。在-10 mA/cm²的电流密度下过电位为-221 mV,塔菲尔(Tafel)斜率为68.1 mV/dec,并且1 000圈CV扫描后过电位没有明显下降,显示出优异的稳定性。     

泡沫镍上原位制备FeOOH/MoSey及电解水双催化性能研究

为设计同时具有优异电催化析氢和析氧性能的过渡金属基催化剂，以泡沫镍为载体和集流体，原位制备了硒化钼(MoSe_y)和羟基氧化铁(FeOOH),得到FeOOH/MoSe_y@Ni复合材料。表征结果表明，先通过电沉积法原位生长了MoSe_y层，再以该MoSe_y层为成核点，通过常温浸泡生长形成了由FeOOH纳米片组成的微米绒球。在三电极体系中，以1 mol·L^-1 KOH溶液为电解液，该FeOOH/MoSe_y@Ni复合材料表现出优异的电催化析氢和析氧性能，析氢电流密度在10 mA·cm^-2时的过电位(η₁₀)为128 mV,析氧电流密度在20 mA·cm^-2时的过电位(η₂₀)为306 mV,并具有较小的Tafel斜率、较大的双电层电容(C_dl)值和良好的稳定性。FeOOH/MoSe_y@Ni优异的电催化性能主要由于三维开放的泡沫镍骨架和原...     

碳化钼/碳纳米片复合材料的制备及析氢性能研究

为了解决Pt基催化剂成本较高的问题,使用电弧放电和高温碳化两步法制备了一种碳纳米片负载碳化钼纳米颗粒的非贵金属催化剂。通过X-射线粉末衍射仪(XRD)、透射电子显微镜(TEM)对催化剂的晶体结构、形貌、碳化钼颗粒尺寸进行了表征分析。结果表明,700℃碳化得到的碳化钼/碳纳米片复合催化剂(Mo_2C/CNS)在酸性电解质溶液中表现出优异的析氢性能。在-10 mA/cm~2的电流密度下过电位为-221 mV,塔菲尔(Tafel)斜率为68.1 mV/dec,并且1 000圈CV扫描后过电位没有明显下降,显示出优异的稳定性。     

大连化物所提出二维硫化钼限域铑原子的距离协同催化效应

<正>近日,中科院大连化物所催化基础国家重点实验室二维材料与能源小分子转化创新特区组邓德会研究员、于良副研究员团队提出二维硫化钼(MoS_2)限域铑原子的距离协同效应,利用铑单原子之间的距离来调控二维MoS_2面内硫原子的电子结构和催化活性,从而实现高效电催化析氢(HER)性能。该工作为深入认识二维MoS_2限域单原子的催化活性调控机制以及设计新型高效电解水析氢催化剂提供了新思路。     

Ni/CrN高效电催化剂的制备及其析氢催化性能

氢能是一种具有高能量密度的清洁能源,如何有效的开发绿氢技术是当前社会首要解决的问题,而研发高效稳定的电解水产氢技术的电催化剂是一种可行性的方式,对促进氢能经济的发展具有重要的意义。通过水热-高温热解两步法合成了一种氮化铬支撑镍纳米颗粒的催化剂(Ni/CrN)。利用XRD、XPS、SEM以及TEM等测试手段对催化剂的形貌及结构进行表征,并在碱性环境下对催化剂进行电催化析氢性能的研究。结果表明,Ni/CrN形成了具有珊瑚状的微观结构,优化了电子结构,并且表现出了优异的析氢反应(HER)催化性能,在10 mA/cm²的电流密度下,Ni/CrN催化剂仅有66 mV的过电位和47 mV/dec的Tafel斜率,十分接近商业的Pt/C催化剂的析氢性能。在10 mA/cm²电流密度的循环稳定性测试中,Ni/CrN表现出比商业Pt/C电极更优越的催化稳定性。     

Pd-NPs@alkyne-PVA/GO复合材料制备及其电催化析氢性能

开发高效、稳定的电催化剂是实现电解水制氢反应(HER)的关键。成功制备以炔基化的聚乙烯醇(alkyne-PVA)改性的单层氧化石墨烯(GO)载体,以硼氢化钠为还原剂,将钯纳米颗粒(Pd-NPs)负载在碳基材料上,合成Pd-NPs@alkyne-PVA/GO复合材料。通过SEM、TEM、XRD、N₂吸附-脱附和XPS对所合成物质的形貌、结构、比表面积及孔径进行分析;采用电化学工作站测试催化剂的线性扫描伏安曲线(LSV)和Tafel 斜率,分析所合成催化剂的电催化析氢性能。结果表明Pd-NPs@alkyne-PVA/GO复合材料在酸性电解质中的电催化性能较好,其在电流密度为-10 mA·cm^-2时,过电位仅为-80 mV。     

MoS2/CNTs电催化析氢性能探究

本文通过一步水热法成功实现了二硫化钼(Mo S₂)在碳纳米管(CNTs)内外壁的原位生长，形成了限域和非限域的Mo S₂/CNTs复合纳米材料，并探究了其对电化学析氢反应(HER)的催化活性。研究结果表明，在碳纳米管内外壁均原位生长出二维片状Mo S₂纳米材料，形成部分限域的Mo S₂/CNTs纳米材料。此外，电催化析氢性能测试显示，Mo S₂生长在适量的CNTs(～25mg)时，形成的Mo S₂/CNTs复合纳米材料表现出较强的HER活性和稳定性。在10mA·cm^-2时，HER的过电位为440mV。Tafel斜率为117mV·dec^-1。     

Synthesis and characterization of cobalt–molybdenum bimetallic carbides catalysts

Co₃Mo₃C, Co₆Mo₆C and MCM41-supported Co₃Mo₃C catalyst are prepared by a simple one-step thermal decomposition method without the conventional temperature-programmed carburization. The resultant carbides are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscope (HRTEM) and BET surface area measurements. The as-prepared Co₃Mo₃C/MCM41 catalyst exhibits good performance in both probe reactions of hydrodesulfurization (HDS) and hydrodenitrogenation (HDN), which proves the one-step decomposition method to be an effective route for the preparation of bimetallic carbide catalyst.     

Facile synthesis and enhanced visible-light photocatalytic activity of Ti3+-doped TiO2 sheets with tunable phase composition? ?

Ti³⁺-doped TiO₂ nanosheets with tunable phase composition (doped TiO₂ (A/R)) were synthesized via a hydrothermal method with high surface area anatase TiO₂ nanosheets TiO₂ (A) as a substrate, structure directing agent, and inhibitor; the activity was evaluated using a probe reaction-photocatalytic CO₂ conversion to methane under visible light irradiation with H₂ as an electron donor and hydrogen source. High-resolution transmission electron microscope (HRTEM), field emission scanning electron microscope, UV-Vis diffuse reflectance spectra, and X-ray diffraction (XRD) etc., were used to characterize the photocatalysts. XRD and HRTEM measurements confirmed the existence of anatase-rutile phase junction, while Ti³⁺ and single-electron-trapped oxygen vacancy in the doped TiO₂ (A/R) photocatalyst were revealed byelectron paramagnetic resonance (EPR) measurements. Effects of hydrothermal synthesis temperature and the amount of added anatase TiO₂ on the photocatalytic activity were elucidated. Significantly enhanced photocatalytic activity of doped TiO₂ (A/R) was observed; under the optimized synthesis conditions, CH₄ generation rate of doped TiO₂ (A/R) was 2.3 times that of Ti³⁺-doped rutile TiO₂.     

Comparison of molybdenum carbide and tungsten carbide for the hydrodesulfurization of dibenzothiophene

The molybdenum and tungsten carbides (Mo₂C and W₂C) were synthesized, characterized and tested in hydrodesulfurization (HDS) of dibenzothiophene (DBT). The phase purity of these catalysts was established by X-ray diffraction (XRD), and the surface properties were determined by N₂ BET specific surface area (Sg) measurements, CO chemisorption and high-resolution transmission electron microscopy (HRTEM). The activities of catalysts were determined during the HDS of DBT at a temperature of 613 K and under a 6 MPa total pressure. Both molybdenum and tungsten carbides were active in HDS of DBT. The reactivity studies showed that molybdenum carbide was more active than tungsten carbide related to weight. However, W₂C was shown to possess stronger hydrogenating properties.     

Comparison between tungsten carbide and molybdenum carbide for the hydrodenitrogenation of carbazole

The activity of molybdenum and tungsten carbides in hydrodenitrogenation (HDN) of carbazole was studied. Transition metal carbides (Mo₂C and W₂C) were synthesized using the temperature-programmed reaction of the appropriate oxide precursor (MoO₃ and WO₃) with the following gas mixture: 10 vol.% CH₄/H₂. The structure of the catalysts was characterized using X-ray diffraction, CO chemisorption, high resolution transmission electron microscopy (HRTEM) and BET surface area measurements. From the HRTEM analysis, it could be concluded that the tungsten carbide was thioresistant in our operating conditions (50 ppm of S, pressure = 6 MPa, 553 < T < 653 K, H₂/feed volumic ratio = 600). In the case of Mo₂C, molybdenum sulphide was observed as single slabs. The activity of catalysts was determined during the hydrodenitrogenation of carbazole at the wide range of temperature (553–653 K) and under a 6 MPa total pressure of H₂. The comparison of tungsten carbide and molybdenum carbide has shown higher activity of Mo₂C than W₂C at the same condition. However, W₂C leads to higher amount of isomers of main products, and have higher hydrogenation activity.     

Acid and base characteristics of molybdenum carbide catalysts

The acid and base properties of a high surface area Mo₂C catalyst were characterized using the temperature programmed desorption of CO₂ and NH₃, the decomposition of isopropyl alcohol (IPA) as a test reaction and monitoring changes in the associated rates and product selectivities on the addition of acid and base site poisons. The Mo₂C catalyst was prepared using the temperature programmed reaction method and passivated prior to exposure to air. Prior to carrying out the temperature programmed desorption experiments and reaction rate measurements, the Mo₂C catalyst was reduced in H₂ at 400 °C. Results obtained for the reduced Mo₂C catalyst were compared with those for MgO, HZSM-5 and 1% Pt/SiO₂ catalysts. The study provided evidence for the presence of both acid and base sites on Mo₂C. The base and acid sites on the Mo₂C catalyst were weaker than those on the MgO and HZSM-5 catalysts, respectively. The base and acid sites were likely created as a consequence of charge transfer from molybdenum to carbon.     

Noble-metal-free cobalt hydroxide nanosheets for efficient electrocatalytic oxidation

Cobalt hydroxide has been emerging as a promising catalyst for the electrocatalytic oxidation reactions, including the oxygen evolution reaction (OER) and glucose oxidation reaction (GOR). Herein, we prepared cobalt hydroxide nanoparticles (CoHP) and cobalt hydroxide nanosheets (CoHS) on nickel foam. In the electrocatalytic OER, CoHS shows an overpotential of 306 mV at a current density of 10 mA·cm^–2. This is enhanced as compared with that of CoHP (367 mV at 10 mA·cm^–2). In addition, CoHS also exhibits an improved performance in the electrocatalytic GOR. The improved electrocatalytic performance of CoHS could be due to the higher ability of the two-dimensional nanosheets on CoHS in electron transfer. These results are useful for fabricating efficient catalysts for electrocatalytic oxidation reactions.     

Microstructure of Molybdenum Disilicide-Silicon Carbide Nanocomposite Thin Films

Composite thin films of molybdenum disilicide-silicon carbide (MoSi₂-SiC) have been deposited via rf magnetron sputtering onto molybdenum substrates. An intermediate layer was deposited in the presence of nitrogen gas and evaluated as a potential diffusion barrier layer. The composite films have been characterized using X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, and Auger electron spectroscopy. The as-deposited films were amorphous but crystallized into nanometer-sized grains after annealing under vacuum at 1000°C for 30 min. There was a significant amount of interdiffusion between the film and substrate, which resulted in the formation of subsilicides such as Mo₅Si₃ and MoSi₃, as well as Mo₂C. The films that were deposited via reactive sputtering in a nitrogen ambient were amorphous in both the as-deposited and annealed conditions. Significantly fewer second phases were detected with the presence of the intermediate layer, which suggests the potential use of the nitrided (MoSi _x N _y C _z ) layer as a high-temperature diffusion barrier layer for the silicon and carbon.     

WC/MMT纳米复合材料制备及其对PNP的电催化活性

以剥离后的蒙脱石(MMT)为载体,将浸渍法与原位还原技术相结合制备了碳化钨/蒙脱石(WC/MMT)纳米复合材料。采用X射线衍射、扫描电子显微镜和透射电子显微镜等手段对样品进行了表征。结果表明,剥离后蒙脱石的片层厚度为10～15 nm,层间距增大,边缘发生卷曲;复合材料由碳化钨(WC)、碳化二钨(W₂C)和蒙脱石组成,碳化钨颗粒均匀地分布于蒙脱石外表面。采用循环伏安法测试了样品对对硝基苯酚(PNP)的电化学还原性能,结果表明,WC/MMT纳米复合材料对对硝基苯酚具有良好的电催化活性,且具有较好的稳定性。蒙脱石是碳化钨基复合电催化材料良好的载体。     

Salt-Templated Nanoarchitectonics of CoSe2-NC Nanosheets as an Efficient Bifunctional Oxygen Electrocatalyst for Water Splitting

Recently, the extensive research of efficient bifunctional electrocatalysts (oxygen evolution reaction (OER) and hydrogen evolution reaction (HER)) on water splitting has drawn increasing attention. Herein, a salt-template strategy is prepared to synthesize nitrogen-doped carbon nanosheets encapsulated with dispersed CoSe₂ nanoparticles (CoSe₂-NC NSs), while the thickness of CoSe₂-NC NSs is only about 3.6 nm. Profiting from the ultrathin morphology, large surface area, and promising electrical conductivity, the CoSe₂-NC NSs exhibited excellent electrocatalytic of 10 mA·cm⁻² current density at small overpotentials of 247 mV for OER and 75 mV for HER. Not only does the nitrogen-doped carbon matrix effectively avoid self-aggregation of CoSe₂ nanoparticles, but it also prevents the corrosion of CoSe₂ from electrolytes and shows favorable durability after long-term stability tests. Furthermore, an overall water-splitting system delivers a current density of 10 mA·cm⁻² at a voltage of 1.54 V with resultants being both the cathode and anode catalyst in alkaline solutions. This work provides a new way to synthesize efficient and nonprecious bifunctional electrocatalysts for water splitting.