TiO2及金属(Cu、Ni)掺杂催化材料水解制氢反应机理的理论研究

本文研究TiO₂以及金属(Cu、Ni)掺杂TiO₂催化剂水解制氢的两种不同析氢反应机理,计算了不同反应过程催化反应活化能,同时考察了系列催化剂电子激发态的催化活性.结果表明:催化剂电子激发态的催化活性增强,说明光照有助于降低反应的活化能,提高催化剂的活性.金属(Cu、Ni)掺杂TiO₂有助于降低水解制氢反应的活化能,且Cu的掺杂催化效果更明显,这与实验报道的结果一致.     

类桑拿法制备的周期性结构Mo金属催化电极及其在电解水制氢中的应用

采用类桑拿法制备了聚苯乙烯微球模板, 结合双层Mo金属结构, 获得了具有周期性结构的Mo金属催化电极. 通控制氧气对聚苯乙烯球的刻蚀时间, 可有效调制Mo金属催化电极的横、纵向尺寸, 从而获得不同的衬底比表面积. 通过原子力显微镜表面形貌测试、电化学线性扫描、塔菲尔测试以及阻抗谱分析表明: 增大刻蚀时间可有效提高Mo金属催化电极的表面粗糙度和比表面积, 进而降低电荷传输电阻和塔菲尔斜率, 促进催化电极/电解液界面处析氢反应的进行. 采用类桑拿法和双层Mo金属结构制备周期性结构的方法简单, 可大面积化, 同时低温磁控溅射法制备的Mo金属催化电极成本低廉, 温度兼容多种太阳电池器件, 具有形成高效一体化光水解制氢器件的潜力.     

超细硫化钼纳米线的电子结构和催化析氢性能的第一性原理研究

本文基于第一原理计算研究了一类新的1D超细硫化钼纳米线,包括Mo_2S_6、Mo_3S_6和Mo_6S_(10)纳米线.通过声子谱计算和600 K下的波恩-奥本海默分子动力学模拟,结果表明这些超细纳米线具有晶格动力学稳定性和较高的热稳定性.计算所得Mo_2S_6、Mo_3S_6和Mo_6S_(10)纳米线的弹性常数分别为21.33、103.22和163.00 eV/A.共中Mo_2S_6,Mo_3S_6纳米线是带隙为1.55和0.46 eV的半导体,而Mo_6S_(10)纳米线则表现为金属.另外,这些超细硫化钼纳米线可以作为催化剂用于析氢反应.对于Mo_2S_6纳米线,其氢吸附自山能变约为-0.05eV,这与Pt和H-MoS_2的氢吸附自由能变相当.这些1D硫化钼纳米线的预测可以丰富1D硫化钼家族,同时为理解过渡金属硫化物在析氢反应上的高效性能作为补充.     

新型非贵金属碳材料的开发及其氧还原性能研究

高效碳基非贵金属氧还原催化剂的开发是燃料电池突破高成本壁垒,实现商业化应用的关键。本文以金属有机框架为前驱体,采用简易的硫化-烧结处理工艺设计获得了一种新型钴/氮掺杂的多孔碳材料。通过对制备工艺进行优化,提高了材料的氧还原催化活性,分析获得了材料的微观结构与氧还原性能之间的相互影响规律,为非贵金属催化剂的开发提供了参考依据。实验结果表明:前躯体包含Zn时,经过900℃高温热解,衍生的催化剂展示了与商用铂碳催化剂媲美的氧还原反应活性、优异的稳定性和良好的抗甲醇能力,其起始电位为1.009 V,半波电位为0.864V,极限电流密度为5.310 mA.cm^-2。     

应变对析氢反应催化剂TiC2性能影响的研究

应变工程是一种有效地用来调整原子薄膜材料的电子、磁性和光学性能的策略.利用第一性原理计算,我们表明应变也可以有效地调节Ti C₂的析氢反应(HER)的催化活性,这是电解水电化学制氢所必需的.我们主要考虑0-8%范围的拉伸应变,研究发现,在25%的氢覆盖率下双轴拉伸比单轴拉伸能更有效的提高HER活性,但b方向拉伸后的Ti C₂结构具有更高的氢最大覆盖率,且b方向的拉伸应变对不同氢覆盖率的Ti C₂单层片的催化性能都有很大的提高.电子结构计算表明,拉伸应变可以激活相对惰性的内部价电子,从而引起体系的失稳和催化活性的提高.在本工作中获得的见解可能有助于利用应变作为一种有效手段来提高二维材料的催化活性,并探索更有效地调整其电子结构和催化活性的新方法.     

Z型InN/SnS2范德华异质结增强光催化水分解

寻找高效的光催化剂分解水制氢是解决能源危机和环境问题的有效途径之一.基于第一性原理,对InN/SnS₂异质结的几何结构、电子结构和光催化水分解性能进行研究.结果表明InN/SnS₂异质结是具有的Ⅱ型能带排列半导体材料可以有效地分离电子空穴对.在光激发下,较小的带隙以及合适的内建电场使得光生载流子迁移路径成“Z”字型,这保留了InN/SnS₂异质结强氧化还原能力.光生电子在InN的导带底累积并发生析氢反应,而积累在SnS₂上的光生空穴使析氧反应自发发生.它们的带边位置都跨越了水的氧化还原电位,证明能够实现水的完全分解.因此,InN/SnS₂异质结有希望成为高效光解水催化剂.     

叠层扩散层对质子交换膜电解池性能影响的实验研究

质子交换膜电解水制氢技术的发展受到成本的约束。通过提高电流密度以提高单位质子交换膜电解池的氢产量可以降低单位应用成本，但高电流密度下电解池内部传质过电势的升高会导致制氢效率的下降。本文从降低质子交换膜电解池在高电流密度下的传质过电势入手，设计了有利于传质的“钛毡–钛网”式叠层扩散层结构，并进行对照实验分析了不同扩散层结构对电解池性能的影响规律。实验证明，钛毡叠加30目钛网的叠层扩散层结构可以使高电流密度(5 A/cm²)下的传质过电势降低至0.25 V(与钛毡或30目钛网作为扩散层相比，传质过电势分别降低了0.24 V与0.55 V)，本项工作也为后续扩散层结构的优化提供了思路。     

基于金属有机框架材料制备Ag-CoSO_4复合纳米材料及其在碱性电催化析氧反应的应用研究（英文）

本文以Co-BTC金属有机框架材料为前驱体,采用连续离子交换法和进一步的高温水热处理来合成片状Ag-CoSO_4复合纳米材料.由于少量Ag的引入有利于增强导电性并加速电子转移过程,该催化剂在1 mol/L KOH电解质溶液中表现出优异的OER性能(在10 mA/cm~2的电流密度下过电位仅为282 mV),其性能甚至比RuO_2更好.催化剂中Ag的存在有利于促进Co(Ⅳ)的产生进而提高Co(Ⅳ)浓度,并且能够调控对氧物种的吸附能而促进OER过程*OOH中间物质的形成,加速了析氧反应过程的进行.极低含量Ag的使用(低于百分之一原子含量)使得催化剂的成本极大的降低.     

NaCu5S3复合NixFe-LDH的结构对水解氧析出性能的影响

析氧反应(OER)在锌空气电池、燃料电池和电解水等能源储存和转换设备中都有至关重要的作用.然而OER过程涉及四电子转移,导致反应动力学缓慢.尽管贵金属氧化物被认为是最先进的OER电催化剂,但昂贵的价格以及稀缺性限制了其商业应用.因此,本工作结合水热和水浴法制备了NaCu₅S₃@Ni_xFe-LDH(x=1,2,3,4)纳米片阵列复合电催化剂.对样品的结构进行了表征,结果显示NaCu₅S₃和Ni₂Fe-LDH充分混合,形成紧密结合的界面,有利于电荷的快速转移,这将增强两相界面处的电子调控作用,改变其局域结构特性,促进OER电催化性能.电化学测试结果显示,当电流密度为20 mA·cm^-2时,NaCu₅S₃@Ni₂Fe-LDH在1.0 M KOH电解液中的氧析出过电位仅为227 mV,电催化性能优于原始的NaCu₅S₃(271 mV)...     

NiSb纳米颗粒的热液路线制备及电催化析氢性能研究（英文）

本文发展了一种简单经济的过渡金属锑化物热液合成路线,在160℃的温和条件下,由商业易得的乙酰丙酮基镍和三苯基铋在汕胺介质中还原制备出NiSb纳米颗粒.反应中,还原剂甲硼烷-叔丁基胺络合物的使用能够有效促进金属源的快速还原,用以促进NiSb纳米颗粒的生成.结构表征显示,所制备的NiSb产物为六方相(空间群P6_3/mmc)颗粒状纳米晶,共粒径约为10 nm.该合成方法可拓展用于CoSb和Ag_3Sb等纳米颗粒的温和制备.电催化析氢性能研究显示,NiSb纳米颗粒具有良好的电化学析氢反应性能.结果显示,当阴极电流密度达到50 mA/cm~2和10 m A/cm~2时所需要的过电位分别为531和437 mV.同时,NiSb纳米颗粒还具有较小的电荷转移阻抗和优良的循环稳定性能.     

Role of graphene in improving catalytic behaviors of AuNPs/MoS2/Gr/Ni-F structure in hydrogen evolution reaction

The efficient production of hydrogen through electrocatalytic decomposition of water has broad prospects in modern energy equipment. However, the catalytic efficiency and durability of hydrogen evolution catalyst are still very deficient, which need to be further explored. Here in this work, we prove that introducing a graphene layer (Gr) between the molybdenum disulfide and nickel foam (Ni-F) substrate can greatly improve the catalytic performance of the hybrid. Owing to the excitation of local surface plasmon resonance (LSPR) of gold nanoparticles (NPs), the electrocatalytic hydrogen releasing activity of the MoS₂/Gr/Ni-F heterostructure is greatly improved. This results in a significant increase in the current density of AuNPs/MoS₂/Gr/Ni-F composite material under light irradiation and in the dark at 0.2 V (versus reversible hydrogen electrode (RHE)), which is much better than in MoS₂/Gr/Ni-F composite materials. The enhancement of hydrogen release can be attributed to the injection of hot electrons into MoS₂/Gr/Ni-F by AuNPs, which will improve the electron density of MoS₂/Gr/Ni-F, promote the reduction of H₂O, and further reduce the activation energy of the electrocatalyst hydrogen evolution reaction (HER). We also prove that the introduction of graphene can improve its stability in acidic catalytic environments. This work provides a new way of designing efficient water splitting system.     

Effect of net carriers at the interconnection layer in tandem organic solar cells

Tandem cell with structure of indium tin oxide (ITO)/molybdenum oxide (MoO₃)/fullerene (C60)/copper phthalocyanine (CuPc)/C60/tris-8-hydroxy-quinolinato aluminum (Alq₃)/Al was fabricated to study the effect of net carriers at the interconnection layer. The open circuit voltage and short circuit current were found to be 1.15 V and 0.56 mA/cm², respectively. Almost the same performance (1.05 V, 0.58 mA/cm²     

Novel molybdenum disulfide nanosheets–decorated polyaniline: Preparation,characterization and enhanced electrocatalytic activity for hydrogen evolution reaction

Novel molybdenum disulfide nanosheets–decorated polyaniline (MoS₂/PANI) was synthesized and investigated as an efficient catalyst for hydrogen evolution reaction (HER). Compared with MoS₂, MoS₂/PANI nanocomposites exhibited higher catalytic activity and lower Tafel slope for HER in H₂SO₄ solution. The amount of 19 wt% PANI for coupling with MoS₂ resulted in a high current density of 80 mA cm⁻² at 400 mV (vs. RHE). In addition, the optimal MoS₂/PANI nanocomposite showed impressive long-term stability even after 500 cycles. The enhanced catalytic activity of MoS₂/PANI nanocomposites was primarily ascribed to the effective electron transport channels of PANI and the increase of electrochemically accessible surface area in composite materials, which was advantageous to facilitate the charge transfer at catalyst/electrolyte interface.     

电化学析氢反应中单层MoSe2氢吸附机理第一性原理研究

基于密度泛函理论的第一性原理方法,本文计算了单层2H相MoSe₂纳米材料表面及两种边缘（Mo原子边缘、Se原子边缘）不同活性位点、不同氢原子吸附率下的氢吸附吉布斯自由能（Gibbs free energy,用△G_H⁰表示）,并且将对应的微观结构进行了系统分析比较,得出△G_H⁰最接近于0 eV的吸附位点及相应的吸附率.同时,结合差分电荷密度和电负性理论,分析了单层MoSe₂两种边缘氢吸附的电荷转移及成键特性,进一步解释了不同吸附位点呈现的结构与能量趋势.最后,通过基于密度泛函理论的第一性原理分子动力学模拟,研究了高温热运动对两种边缘氢吸附的影响,获得了氢原子发生脱附的临界温度及对应的微观动态过程.该理论研究从原子尺度揭示了单层2H相MoSe₂纳米材料边缘不同位点在不同温度下对氢原子吸附和脱附的微观机理,证实了Mo原子边缘的畸变和重构行为,加深了对实验中单层2H相MoSe₂边缘在不同温度下氢吸附机理的理解,为实验中通过控制MoSe₂边缘设计廉价高效的析氢催化剂提供理论参考.     

铜-钼源漏电极对非晶氧化铟镓锌薄膜晶体管性能的改善

在铜(Cu)和非晶铟镓锌氧化物(a-IGZO)之间插入30 nm厚的钼(Mo)接触层, 制备了具有Cu-Mo源漏电极的a-IGZO薄膜晶体管(TFT). Mo接触层不仅能够抑制Cu与a-IGZO有源层之间的扩散, 而且提高了Cu电极与玻璃基底以及栅极绝缘层的结合强度. 制备的Cu-Mo结构TFT与纯Cu 结构TFT相比, 具有较高的迁移率(～9.26 cm²·V^-1·s^-1)、更短的电流传输长度(～0.2 μm)、更低的接触电阻(～1072 Ω)和有效接触电阻率(～1×10^-4Ω·cm²), 能够满足TFT 阵列高导互联的要求.     

基于窄带隙聚合物的高性能可见-近红外光伏探测器

聚合物光伏探测器是一种极具应用前景的新型光电探测器件.研究了基于窄带隙聚合物的高性能可见-近红外光伏探测器,结果表明,所制备的光伏探测器在可见至近红外光谱范围内具有宽的光谱响应(380—960 nm)、出色的响应度(840 nm时达到380 mA/W)和归一化探测度;同时,器件在暗态反偏条件下的能级示意图揭示了器件内平均电场较低是较厚光敏层器件具有低噪声电流的主要原因.电容-电压与时间周期性响应曲线研究表明聚合物光伏探测器具有快速的响应能力和良好的周期重复性.     

PECVD分层结构对提高氢化非晶硅TFT迁移率的影响

为了进一步提高氢化非晶硅薄膜晶体管 (a-Si:H TFT) 的场效应电子迁移率, 研究了批量生产条件下对欧姆接触层和栅极绝缘层进行多层 制备, 不同的工艺参数对a-Si:H TFT场效应电子迁移率的影响. 研究表明随着对欧姆接触层 (n⁺层) 分层数的增加, 以及低速生长的栅极绝缘层 (GL层) 和高速生长的栅极绝缘层 (GH 层) 厚度比值提高, a-Si:H TFT的场效应迁移率得到提升. 当n⁺层分层数达到 3层, GL层和GH层厚度比值为4:11 时, 器件的场效应电子迁移率达到0.66 cm²/V·s, 比传统工艺提高了约一倍, 显著改善了a-Si:H TFT 的电学特性, 并在量产线上得到了验证. 关键词： 非晶硅薄膜晶体管 电子迁移率 欧姆接触层 栅极绝缘层     

Chemical effects of Ne bombardment on the MoS2(0001) surface studied by high-resolution photoelectron spectroscopy

The effect of 1 keV Ne⁺ bombardment on the clean MoS₂(0001)-1 × 1 surface with fluences between 4 × 10¹⁴ and 4 × 10¹⁶ Ne⁺/cm² was studied using high-resolution photoelectron spectroscopy excited with synchrotron radiation. Spectra of the Mo 3d and S 2p core levels were measured with photon energies that ensured that the kinetic energy of the photoelectrons was the same, resulting in the same depth being probed for both core levels. For lower fluences (i.e., 2 × 10¹⁵ Ne⁺/cm²), S vacancy defect formation occurs in the MoS₂ lattice, with the concurrent formation of a small amount (< 10%) of dispersed elemental molybdenum [Mo(0)]. For fluences greater than l × 10¹⁶ Ne⁺/cm², the Mo(0) is the predominant species in the surface region, while the remaining species consist of amorphous MoS_2−x and polysulfide species. Valence band spectra taken with photon energies of 152 and 225 eV were consistent with the core level results. The movement of the valence band maximum toward the Fermi level indicated the formation of a metallic surface region. Annealing the sample to temperatures up to 1000 K resulted in the formation of metallic Mo coexisting, in approximately equal amounts, with reformed MoS₂ in a surface with no long-range order as determined by LEED. Finally, a qualitative depth distribution of the chemical species present after Ne⁺ bombardment was determined by varying the photon energies used for the core level spectra. The results indicate that the preferential sputtering of sulfur over molybdenum occurs predominantly through a mechanism involving chemical bonding effects, specifically, through the preferential emission of polysulfide ions over other species in the bombarded region.     

Effect of Ag promoter on redox properties and catalytic performance of Ag-Mo-P-O catalysts for oxidative dehydrogenation of propane

The influence of addition of sliver ions on the redox properties and catalytic performance of molybdenum-phosphate catalyst in oxidative dehydrogenation (ODH) of propane has been investigated. MoO₃ and AgMoO₂PO₄ have been detected in Ag-doped Mo-P-O catalysts. The redox properties have been characterized by H₂-temperature-programmed reduction (TPR), electronic paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS). The catalytic performance of MoO₃, Ag₂O, AgMoO₂PO₄ and Ag-doped Mo-P-O catalysts has also been examined. The incorporation of Ag improved the number of Mo⁵⁺ species and the reducibility of the catalysts. The Ag-doped catalysts favor activity and selectivity in ODH of propane higher than the undoped catalyst. The best catalyst was obtained with Ag/Mo ratio of 0.3 and MoO₃/AgMoO₂PO₄ ratio of 1.1. The influence of promoter Ag⁺ on redox properties and catalytic performance is due to forming redox couple “Ag⁰+Mo⁶⁺Ag⁺+Mo⁵⁺” and the synergetic effect originating from “coherent interface” between MoO₃ and AgMoO₂PO₄.