高效Mo-Ni5P4双功能电催化剂的制备及其电解水性能研究

电催化制氢通过析氢反应(HER)和析氧反应(OER)同时产生氢气(H₂)和氧气(O₂),是一种高效且环境友好的产氢方式。但现阶段商业化的高效催化剂价格昂贵且储量较少，限制了电解水技术的大规模应用。因此，开发低成本、高稳定和环境友好的高效电催化剂，特别是基于非贵金属材料的磷化物电催化剂，成为近期研究热点。本研究通过水热和相对较低的磷化温度成功制备出了具有镂空纳米花结构的Mo掺杂Ni₅P₄催化剂。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对Mo-Ni₅P₄催化剂进行了表征，并研究了Mo-Ni₅P₄材料的电化学性能。研究发现，所合成的催化剂凭借掺杂对电子结构的改变，以及多孔纳米片的大表面积优势，提高了HER水解离步骤的速率。在碱性电解液中，Mo负载下的Ni₅P₄仅需116 mV的析氢过电位就可实现10 mA·cm^-2的电...     

高价态W掺杂对NiFe磷化物全分解水制氢催化活性影响的研究

近年来，通过光伏辅助电催化(PV-EC)分解水制备“绿氢”成为实现碳中和目标的关键。然而，普通电解水催化剂不能满足PV-EC系统中较高的太阳能到氢能(STH)转换效率的需求。因此，获取价格低廉、低反应过电势的电催化剂材料极为重要。本文选取具有高价态的过渡金属W作为掺杂源，采用一步电沉积方法制备出NiFeW三元金属磷化物。通过一系列的表征发现，NiFeW磷化物电催化剂表现出优异的析氢反应(HER)和析氧反应(OER)活性，且作为双功能电催化剂时，在10 mA/cm²电流密度下W掺杂后样品的过电势降低了51 mV。使用NiFeW磷化物作为双功能电催化剂和太阳能电池(a-Si∶H/a-SiGe∶H/a-SiGe∶H)作为驱动源，PV-EC器件实现了超过7%的理论STH转换效率，对推动太阳能分解水制氢装置的实际应用具有重要意义。     

膜电极厚度对电极材料析氢活性的影响

用直流磁控溅射法制备不同厚度的膜电极材料.在室温,1mol/L KOH溶液中,这些膜电极材料析氢反应的过电位和膜电极的厚度有关:在一定厚度范围内,膜电极越厚,析氢过电位越小,不同膜电极材料都表现出这样的规律,只是大小和对厚度的依赖程度有所不同.这些结果表明析氢反应不只是发生在电极表面的范围内,反应过程中形成的金属氢化物由于深入到材料内部,从而出现了厚度对析氢反应过电位的影响,并且由于材料不同,可形成的金属氢化物厚度不同,所以对过电位的影响也就不同.     

射频等离子制备石墨烯负载Co3O4催化剂及其析氧性能研究

氢能的引入能有效提升配电网的供电可靠性,而电解水制氢是实现低碳转型的关键技术,开发高效的电解水催化剂势在必行。过渡金属氧化物储量大、催化活性高,是具有广阔应用前景的析氧反应催化剂。本文通过射频等离子体处理制备石墨烯上负载Co₃O₄析氧催化剂,XRD、Raman和XPS测试结果显示,二维结构石墨烯的引入加速表面电子迁移,增大了反应面积。等离子体处理促进了纳米粒子在石墨烯上的负载,利用等离子体刻蚀作用在催化剂表面制造出大量碳结构缺陷和氧空位结构,改善了活性位点分布,有效调控Co₃O₄电子结构,提高析氧催化活性。电化学测试表明,本文中合成的Co₃O₄@rGO在电流密度为50 mA·cm^-2时的过电位为410 mV,动力学反应速率较快,表现出优于商业IrO₂的析氧催化活性。     

纳米针阵列多孔材料3D CoP@CC的制备与电催化析氢性能研究

采用水热法在碳布基底上沉积了前驱体,然后在Ar气气氛中加热并用次磷酸钠在300～350℃磷化得到了纳米针阵列多孔材料3D CoP@CC,并分析了所得样品的物相、微观结构和电催化性能.XRD分析结果表明所得材料本体为正交结构的CoP,SEM分析结果表明所得阵列结构纳米针的直径在100 nm以下,长度约为10μm.电催化性能分析结果表明,制备所得该3D CoP@CC作为催化材料在0.5 mol/L硫酸溶液中表现出优异的电催化析氢性能,当电流密度为10 mA·cm-2时,过电位为124 mV.Tafel斜率为84.9 mV/dec,说明该3D CoP-CC电催化析氢的控速步为Volmer反应.从阻抗图谱可以看出有两个不完整的半圆弧,表明其具有两个时间常数,CPE2-P=0.5019意味着粗糙和多孔的电极表面产生了双层电容,电荷较难穿透,表明了阻抗的来源主要是传质与传荷.     

高性能、可弯曲碳纳米管纤维负载镍磷合金电催化析氢电极的研究

利用电化学沉积法在碳纳米管纤维(CNTFs)上沉积了镍磷合金,对比了不同循环圈数、不同镍磷比例下制备的碳纳米管纤维负载镍磷合金(Ni-P/CNTFs)电极在中性电解质溶液中的电催化析氢性能,发现当电沉积液中镍磷比为2:1时,沉积50圈时制备出的样品具有最佳的电催化析氢性能,产生10 mA·cm-2电流密度仅需138 mV过电势,塔菲尔(Tafel)斜率为83 mV·dec-1,同时具有良好的稳定性.并且在保持催化性能不变的前提下,样品可以进行弯曲,扩展了应用领域.     

Ni2P@2D磷烯双功能电催化剂在光伏辅助全分解水制氢中的应用研究

近年来，二维磷烯(2D BP)因其较短的电荷传输距离、高载流子迁移率和充分暴露的表面活性位点，成为电催化剂的理想材料。然而，不适合的含氧中间体吸附能使其反应动力学迟缓，进而限制了其实际应用。本文通过引入颗粒状的非晶Ni₂P化合物，构建Ni₂P@BP异质结，在改善反应活性的基础上，提高其电化学稳定性。研究结果表明：相较于纯BP和Ni₂P电催化剂，Ni₂P@BP催化剂展现出优异的析氢(HER)和析氧(OER)催化活性，在10 mA/cm²电流密度下的过电势分别为167和186 mV。Ni₂P@BP作为双功能电催化剂，仅需1.54 V的外加偏压(V_app)就可以实现10 mA/cm²的电流密度。将其与a-Si∶H/a-SiGe∶H/a-SiGe∶H三结叠层太阳电池连接，实现了超过7%的太阳能制氢(STH)转换效率，相较于作为双功能电催化剂的纯BP提高了95%。     

铂/铜合金催化剂的制备及其电解水析氢性能研究

面对化石能源危机问题，清洁高效的氢能源受到人们的广泛关注，电解水制氢成为新的研究热点。本文主要围绕铂/铜合金催化剂的合成、表征及其电解水析氢催化应用展开研究。采用溶剂热法合成铂/铜合金，通过XRD、SEM、TEM、EDS、XPS等表征铂/铜合金的组成结构和微观形貌，对铂/铜合金的构效关系进行探索。利用电化学测试系统测得铂/铜合金不同条件下的析氢催化性能。在0.5 mol/L H₂SO₄中，铂/铜合金的起始过电位为20.3 mV(10 mA·cm^-2时),塔菲尔斜率为37.56 mV·dec^-1;在1 mol/L磷酸缓冲盐溶液(PBS)中，铂/铜合金的起始过电位为35.0 mV(10 mA·cm^-2时),塔菲尔斜率为52.12 mV·dec^-1;在1 mol/L KOH中，铂/铜合金的起始过电位为25.3 mV(10 mA·cm^-2时),塔菲尔斜率为36.82 mV·dec^-1。对比发现，铂/铜合金在酸性电解质中展...     

溅射腔气压对电极材料析氢活性的影响

采用直流磁控溅射法制备了析氢反应的电极材料-NiFe,CoMo,研究了在1.0Pa～4.0Pa的范围内,不同溅射腔气压条件下制备的电极材料的晶粒尺寸、析氢反应的过电位与气压的关系,结果显示过电位随气压升高而降低,而且在2.0Pa处,过电位变化的程度和Tafel斜率均发生突变,表明不同溅射气压下制备的材料晶粒尺寸的变化,引起了析氢反应控制步骤的改变.     

钴掺杂碳活化过硫酸氢钾降解四环素

本文以无水葡萄糖和六水合硝酸钴为原料，采用水热法与原位负载相结合制备了一种掺钴的碳基化合物，并将其作为过硫酸氢钾活化剂用于催化降解水体中的四环素。对制备的掺钴碳基化合物进行了XRD、SEM、TEM、XPS等表征，从晶形结构、显微形貌、表面化学元素等方面分析了该催化剂降解四环素效果明显高于单一水热碳的原因。此外，考察了催化剂投加量、过硫酸氢钾投加量、溶液pH等因素对四环素催化降解效果的影响。实验结果表明：掺钴碳基化合物在最佳反应条件下催化降解60 min,四环素的降解率达到了95.84%(k=0.051 36 min^-1)。同时还对降解机理进行了探究，分析结果表明掺钴碳基材料中的Co⁰和Co²⁺参与了激活过硫酸氢钾产生·O^-₂、SO₄^·-、¹O₂、·OH的过程，该材料具有高效的催化降解四环素的能力，在处理抗生素废水方面具有良好的前景。     

rGO/TiO2及其三元复合材料光催化性能的研究进展

rGO/TiO2复合材料优异的光催化性能为其在有机染料降解,雨水消毒和催化析氢等方面的应用提供可能,通过与金属、金属化合物或高聚物复合可提升光催化效率和化学稳定性.分析反应机理,阐述现阶段研究的重点和不足,同时对未来发展和应用进行展望.     

Peculiarities of aluminium interaction with Ga85In15 eutectics as evidenced by X-ray synchrotron diagnostics

A set of X-ray synchrotron techniques, viz., diffraction, EXAFS/XANES spectroscopy and microtomography, is applied to elucidate microstructural changes in a technical aluminium alloy treated with GaIn eutectics. Such a treatment gives rise simultaneously to a prominent enbrittlement of the material and its activation towards reaction with water with the hydrogen evolution. The latter fact makes the activated aluminium a promising energy carrier for the small-scale hydrogen energetics. It is demonstrated that both phenomena are caused by the fast diffusion of the eutectics along intergrain boundaries and microcracks throughout the bulk of polycrystalline Al. The diffusion is promoted by the formation of (Al-Ga-In) solid solution in near-surface regions of Al crystalline grains. The progressive loss of activity of aluminium treated with GaIn eutectics upon a prolonged storage in humid air is due to the decomposition of the eutectics accompanied by the segregation of indium metal and partial gallium oxidation.     

Molecular mobility in piezoelectric hybrid nanocomposites with 0-3 connectivity: Particles size influence

Polyamide 11/barium titanate nanocomposites have been studied by a combination of dynamic dielectric spectroscopy, thermo stimulated current and differential scanning calorimetry. The correlation between results obtained by dielectric and calorimetric methods allows us to describe the evolution of the physical structure of the hybrid nanocomposites. The molecular mobility of 0-3 connectivity nanocomposites has been explored. The influence of the nanoparticles size is specifically studied. The smaller sized fillers produce a shift of the relaxation modes observed above the glass transition temperature of polyamide 11 towards lower frequency. The increase of the organic/inorganic interface induces an increase of the ratio rigid amorphous phase/soft amorphous phase. The interfaces favour local ordering stabilized by hydrogen bonds at a nanometric scale.     

On the electrochemical behaviour of undercooled melts and glasses

The electrochemical behaviour of undercooled melts and glasses is considered in detail. First the thermodynamic properties of the corresponding phases are calculated and then the temperature course of the emf and of other thermodynamic functions of a galvanic cell in which the net reaction is: undercooled melt (glass)→crystal, are determined. Some additional problems concerning the electrochemistry of amorphous electrodes are analyzed, e.g. hydrogen overvoltage upon hydrogen evolution on crystalline or amorphous electrodes of a given metal. Several variants are discussed for the possible experimental realization of a galvanic cell in which the emf is determined by the difference in the chemical potentials of the undercooled melt (or the glass) and the crystal, i.e. of a galvanic cell with a vitreous and a crystalline electrode made of one and the same electronic conductor or of a bipolar cell with an amorphous and a crystalline electrolyte, etc. An attempt is made to estimate the interal electric (Galvani) potential at the melt/crystal interface by using data for the difference of the Peltier coefficient between the respective phases.The analysis of the electrochemical behaviour of vitreous, liquid and crystalline electrodes is performed on the basis of formal thermodynamics and in terms of classical model approaches. It is shown how to determine by electrochemical measurements the main thermodynamic parameters of glasses which are considered as frozen-in non-equilibrium systems.     

CuO-NiO/SnO2光催化剂的制备、表征及产氢性能

采用溶胶-凝胶法制备纳米SnO2,通过浸渍法制备CuO-NiO/SnO2光催化材料,采用XRD、UV-Vis DRS、TEM及HRTEM对其结构、形貌及光吸收性能进行表征。在紫外灯照射下,以无水乙醇为电子给体,详细考察了CuO掺杂量、NiO掺杂量、乙醇浓度等对SnO2光催化产氢性能的影响。研究结果表明:5%CuO-7%NiO/SnO2的光催化产氢性能最佳,约是同条件下纯SnO2产氢性能的2.8倍;最优乙醇浓度约为1.2 mol/L。     

A study on hydrogen-induced amorphization in the La---Ni system

In order to investigate the mechanism of hydrogen-induced amorphization, the structure changes by hydrogen absorption in La₂Ni₇, LaNi₂, LaNi_1.5 and LaNi compounds are investigated by X-ray diffraction. Also thermal stabilities of the hydrogenated samples are examined by DSC and hydrogen desorption technique. In case of La₂Ni₇ compound, the severe lattice distortion is found as hydrogen is absorbed. However, as the hydrogen absorption-desorption cycle is repeated, the amorphization takes place. LaNi₂ and LaNi_1.5 compounds show the complete absence of diffraction lines when hydrogenated at room temperature, i.e. the hydrogen-induced amorphization has occurred. The DSC curve of the hydrogen-induced amorphous alloy shows a small exothermic peak related to the precipitation of LaH₂ and LaNi₅. LaNi compound may transform into another crystalline structure by hydrogenation at room temperature, which is different from that of original LaNi compound. It is suggested that the amorphization of a compound is dependent upon the stability of the compound and the decomposition rate to LaH₂ and LaNi₅. The mechanism of the amorphization is related to the lattice distortion caused by the motion of the metal atoms so that the surroundings of the hydrogen atoms in the amorphous state resemble those of hydrogen atoms in LaH₂.     

Substrate temperature dependence of microcrystalline silicon growth by PECVD technique

Undoped hydrogenated silicon films have been prepared from a gas mixture of silane and hydrogen, varying substrate temperature from 180–380 °C in an ultrahigh vacuum system using RFPECVD technique. XRD and Raman measurements enable us to know that the films are microcrystalline throughout the substrate temperature range. Bond formation of the SiH films at different substrate temperature is studied through different characterisation techniques like Fourier transform infrared spectroscopy and hydrogen evolution study. The infrared absorption spectroscopy and hydrogen evolution study reveal two types of growth: the formation of a void rich material at low T_s (∼180 °C) and a compact material at comparatively higher T_s.     

Vibrational studies of metal cation reduction at oxide glass surfaces

Reduction of metal oxide metaphosphate glasses (M₂O · P₂O₅, or MO · P₂O₅, where M is a metal cation) is observed above ca. 100°C when the glass is treated with one several gaseous reducing agents such as H₂, atomic hydrogen, Hg or K. Such amorphous systems are characterized by rapid cation diffusion, with cation reduction occurring principally at the glass surface, which leads to metal cluster formation and eventual continuous metal film growth. Structural changes induced in the glass by cation migration and subsequent reduction are studied by transmission infrared spectroscopy on thin-film samples during the reaction. Scanning electron microscopy and Raman spectroscopy are also employed to study and characterize the glass surfaces. The effect of water vapor on increasing the reaction rate for the mercuric metaphosphate/hydrogen reaction is demonstrated by continuous measurements of vibrational intensity changes. Surface-adsorbed water is seen to reduce the reaction induction period with little effect on the subsequent reaction rate. These results suggest that the rate-determining step of metal ion reduction at glass surface is a diffusion-limited process.     

FTIR and absorption edge studies on tungsten oxide based precursor materials synthesized by sol-gel technique

The sol-gel technique has been employed for synthesizing three precursor materials for the deposition of tungsten oxide based electrochromic films. The ion-exchange route yields tungstic acid precursor (ITA) which has a strong tendency to polymerize rapidly. Addition of hydrogen peroxide and/or acetic acid suppresses the gelation process and an ethanol soluble precursor material (AIPTA) possessing a low degree of polymerization and high chemical stability is obtained. Another precursor material APTA endowed with similar desirable characteristics is produced from direct reaction between tungsten metal powder and a mixture of hydrogen peroxide and acetic acid. These materials were characterized by FTIR and absorption edge studies and compared in terms of their degree of polymerization and modes of association of various functionalities with the tungsten metal ion.