Mo掺杂对Pt/C催化剂乙醇氧化催化性能的影响

直接乙醇燃料电池(DEFC)由于其高能量密度、绿色无污染等优势受到广泛关注, 寻找和开发具有高乙醇氧化催化活性和抗CO中毒能力的阳极催化剂对DEFC的未来发展和商业应用具有重要意义。本研究采用微波法合成了一系列Mo掺杂的Pt/C催化剂, 并通过循环伏安法、交流阻抗法、计时电流法等电化学技术考察了Mo的掺杂量对Pt/C催化剂乙醇氧化催化活性和稳定性的影响。结果表明: Pt₂Mo/C催化剂在乙醇氧化催化过程中表现出与Pt/C相当的起始电位、最大的峰电流密度和最慢的衰减速度, 说明该催化剂具有最高的乙醇氧化催化活性和最稳定的工作性能。     

炭气凝胶负载Pt基催化剂的制备及其甲醇氧化催化性能

以间苯二酚(R)和甲醛(F)为原料,制备R-F炭气凝胶(RF-CAs).继以后者为载体采用浸渍还原法制备铂基催化剂Pt/CA,并比较其与由相同负载工艺制得的以Vulcan XC-72为载体的铂基催化剂Pt/XC72的催化甲醇氧化反应的性能.结果表明,前者具明显高的甲醇氧化催化活性,显示CAs是一种极具潜在竞争力的燃料电池催化剂载体材料.     

高分散度Pt/C电催化剂的制备

Cabot公司Vulcan XC-72型炭黑，经过H2O2氧化处理后作为Pt的载体，H2PtCl6作为金属前驱体制备了高度分散的Pt/C催化剂。讨论了不同条件下H2PtCl6在炭黑上的吸附性能。载体经过H2O2氧化处理24h,H2PtCl6在pH=9下吸收48h，H2 350℃还原2h，可以制备出铂晶粒平均大小为1.8nm的Pt/C电催化剂。     

质子交换膜燃料电池中Pt/C及Pt合金/C催化剂的衰退机制研究综述

成本和耐久性依然是制约质子交换膜燃料电池商业化发展的两大瓶颈。首先综述了质子交换膜燃料电池阴极Pt/C催化剂在实际工作条件下的降解情况,并给出了可能的降解机制。结果表明,Pt/C催化剂在实际工作条件下,尤其是在汽车应用中是不稳定的,通常无法用作燃料电池阴极催化剂。而Pt合金催化剂因具有优异的氧还原催化性能和相对较好的耐久性,被认为有望解决成本和耐久性这两大难题,因此在质子交换膜燃料电池中日益得到重视和应用。但如何改善合金催化剂的耐久性依然是一个棘手的问题,文章最后详细综述了PtxCoy合金催化剂可能的衰退机理,以及可在一定程度上提高Pt合金催化剂耐久性的Pt单层结构和Pt核壳结构,这对催化剂的合成和设计具有一定的指导意义。     

Pt/MoO3/ZrO2催化剂的制备及三效催化性能的研究

采用浸渍法制备了MoOz/ZrO2,用低温氮吸附-脱附法和NH3-程序升温脱附法(TPD)分别对其比表面积和酸碱性进行了表征.结果表明,MoO3/ZrO2具有106.8m2/g的比表面积和超强酸的性能.用等体积浸渍法制备了Pt/MoO3/ZrO2催化剂,在汽车尾气模拟气中考察了其对C3H8、CO和NO的催化活性.与传统三效催化剂Pt/La2O3/Al2O3相比较,Pt/MoO3/ZrO2具有更好的低温起燃性能和更宽的空燃比窗口,并显著地改善了C3H8在富氧状态下的转化效率.通过XRD、H2-TPR对催化剂进行了表征,结果表明,Pt在催化剂载体上具有高度的分散性和优异的氧化还原性能.     

Nafion及水醇比对Pt/C催化剂活性的影响

运用电化学测试的方法研究了在不加Nafion(全氟磺酸聚合物)的情况下水和异丙醇比例对Pt/C催化剂墨水分布均匀性及其电化学活性的影响,同时研究了Nafion的存在对Pt/C电极电化学性能的影响。结果表明,随着异丙醇含量的增加,Pt/C墨水分散越好,活性面积和粗糙因子越大;Nafion的存在对催化剂的活性面积基本没有影响,然而含有Nafion的催化剂氧还原极限电流密度明显降低。     

纳米Au/C催化剂的制备及催化应用研究

选择柠檬酸钠还原法制备尺寸可控的胶体Au纳米粒子溶液,用TEM和UV-Vis吸收光谱对Au纳米粒子的尺寸及形貌进行了表征。然后将Au纳米粒子负载于活性炭上制得了Au/C催化剂。将Au/C催化剂用于液相催化氧化葡萄糖和乙二醛反应,结果表明Au/C催化剂的催化活性较高,这一制备方法较为成功。并对催化反应机理进行了探讨。     

乙二醇稳定的NaBH4还原法制备纳米Pt/C催化剂

分别采用乙二醇(EG)和H2O为溶剂,通过NaBH4还原法在酸性pH≤2和碱性pH≥12条件下制备了铂担裁量为20%(质量分数)的Pt/C催化剂,利用TEM、CV及LSV等方法对催化剂进行了表征与测试,考察了EG在NaBH4还原法中对铂纳米颗粒的稳定作用.结果表明,EG作溶剂、碱性pH≥12时,通过NaBH4还原法制备得到了平均粒径约2.5nm、粒径分布窄、在碳裁体上分散均匀的Pt/C催化荆;该催化剂的电化学比表面为74.4m2/g Pt,0.8V vs NHE时通过LSV得到的单位质量铂对甲醇电催化氧化的电流密度为229.1mA/mg Pt,分别是相同条件下H2O作溶剂时制备得到的Pt/C催化剂的5.倍和5.3倍.     

氢气还原法制备Pt/MoOx/C及其对氧还原的电催化性能

用氢气在高温下还原吸附到碳载体上的钼酸铵和氟铂酸,制备出Pt/MoOx/C金属-氧化物复合型催化剂.考察了Pt/MoOx/C催化剂的电化学性能,经旋转圆盘电极测试表明在低电位区Pt/MoOx/C对含甲醇溶液中的氧还原的催化活性高于Pt/C.     

燃料电池用高效Pt/C催化电极材料的结构和电化学性能研究

采用离子束溅射技术制备Pt/C催化电极(Pt层厚度为50nm),电极耗铂量降低至0.10mg/cm2,电极具有良好的电化学性能.研究了碳质载体上不同沉积条件制备的Pt/C催化电极的结构和电化学性能.结果表明Pt膜为fcc结构,采用高束电压高束电流情况下沉积的铂电极电化学性能有显著提高.电极连续运转1000小时后催化活性未明显下降.     

纳米金催化剂Au/ZnAl-LDHs的制备及在CO常温氧化反应中的活性及稳定性

以人工合成的双羟基金属氢氧化物ZnAl-LDHs为载体,将预先制备的金溶胶通过静电吸附的方式负载到载体上,获得了纳米金催化剂Au/ZnAl-LDHs,用X射线粉末衍射(XRD)表征了催化剂的物相,用透射电镜(TEM)观察了纳米金颗粒的粒径分布,以CO的常温催化氧化为模型反应,分别考察了金溶胶制备过程中金前体HAuCl4·6H2O的浓度和还原剂THPC的用量、负载过程的pH值以及金的负载量等因素对金催化剂的活性和稳定性的影响。结果表明:在制备金溶胶的过程中,降低HAuCl4·6H2O的浓度并提高还原剂THPC的用量,可以制备出粒径分布处于1~7nm之间、平均粒径仅3.87nm的负载型纳米金颗粒,其对CO的常温转化率为100%,且其催化活性的稳定性明显提高;而在金溶胶的吸附负载过程中,使体系的pH值处于6~7的范围,有利于金溶胶在ZnAl-LDHs载体上的吸附负载,从而得到实际负载量更接近理论负载量的金催化剂样品,当金的实际负载量接近1%(质量分数)时,能够确保对CO的常温氧化转化率达到100%。     

Preparation and catalytic activity of Pt/C materials via microwave irradiation

Microwave heating was employed to prepare highly dispersed Pt/C catalyst. Uniform platinum nanoparticles with average diameter of about 3.0-5.0 nm dispersed on carbon materials (XC-72) were synthesized using a domestic microwave oven. Synthesized Pt/C materials were characterized by X-ray diffraction and transmission electron microscopy. The particle size and size distribution of Pt nanoparticles greatly depend on microwave irradiation duration, where the heating temperature rises rapidly as the process proceeds. Cyclic voltammetry demonstrates that Pt/C catalysts derived from microwave irradiation for 90 s exhibits higher catalytic activity than a commercial Pt/C catalyst (E-Tek) at room temperature. The improvement in electrocatalytic activity of synthesized Pt/C materials is attributed to uniformity of particle size, well dispersion and high surface area, which is obtained around 175 °C and irradiation for 90 s.     

Atomic Carbon Layers Supported Pt Nanoparticles for Minimized CO Poisoning and Maximized Methanol Oxidation

Maximizing activity of Pt catalysts toward methanol oxidation reaction (MOR) together with minimized poisoning of adsorbed CO during MOR still remains a big challenge. In the present work, uniform and well‐distributed Pt nanoparticles (NPs) grown on an atomic carbon layer, that is in situ formed by means of dry‐etching of silicon carbide nanoparticles (SiC NPs) with CCl₄ gas, are explored as potential catalysts for MOR. Significantly, as‐synthesized catalysts exhibit remarkably higher MOR catalytic activity (e.g., 647.63 mA mg^?1 at a peak potential of 0.85 V vs RHE) and much improved anti‐CO poisoning ability than the commercial Pt/C catalysts, Pt/carbon nanotubes, and Pt/graphene catalysts. Moreover, the amount of expensive Pt is a few times lower than that of the commercial and reported catalyst systems. As confirmed from density functional theory (DFT) calculations and X‐ray absorption fine structure (XAFS) measurements, such high performance is due to reduced adsorption energy of CO on the Pt NPs and an increased amount of adsorbed energy OH species that remove adsorbed CO fast and efficiently. Therefore, these catalysts can be utilized for the development of large‐scale and industry‐orientated direct methanol fuel cells.     

Pt Single Atoms on CrN Nanoparticles Deliver Outstanding Activity and CO Tolerance in the Hydrogen Oxidation Reaction

The large-scale application of proton exchange membrane fuel cells is currently hampered by high cost of commercial Pt catalysts and their susceptibility to poisoning by CO impurities in H₂ feed. In this context, the development of CO-tolerant electrocatalysts with high Pt atom utilization efficiency for hydrogen oxidation reaction (HOR) is of critical importance. Herein, Pt single atoms are successfully immobilized on chromium nitride nanoparticles by atomic layer deposition method, denoted as Pt SACs/CrN. Electrochemical tests establish Pt SACs/CrN to be a very efficient HOR catalyst, with a mass activity that is 5.7 times higher than commercial PtRu/C. Strikingly, the excellent performance of Pt SACs/CrN is maintained after introducing 1000 ppm of CO in H₂ feed. The excellent CO-tolerance of Pt SACs/CrN is related to weaker CO adsorption on Pt single atoms. This work provides guidelines for the design and construction of active and CO-tolerant catalysts for HOR.     

Pt／C催化剂的制备及其对甲醇电催化氧化的研究

首次报道了以乙二胺四乙酸（EDTA）作为螯合剂,采用硼氢化钠还原氯铂酸制备Pt／C（Pt的质量分数为20％）纳米催化剂,TEM分析表明,通过改变反应的pH值可以获得分散度与粒径不同的Pt粒子,当pH=12．5时,Pt的分散度最高,平均粒径最小（3．2nm）。催化剂的退火处理研究表明,经270℃氮气氛围内退火后,其电催化活性有了显著提高。使用循环伏安法在甲醇的溶液中电催化氧化研究结果表明,在pH=12．5时制备的催化剂对甲醇的电催化氧化活性最高。     

炭/炭复合材料自愈合涂层的制备及其抗氧化性能

为了拓展C/C复合材料作为高温结构材料的应用领域,作者研究制备了一种具有自愈合功能的 C/C复合材料抗氧化涂层,它主要由SiC和Si-B-Al-Cr-Zr系陶瓷氧化物构成.静态干燥空气中的氧化试验显示,对应700～1 000 ℃的平均氧化失重率约为2.91×10-7～9.43×10-6 g/(cm2·s);涂层在1 000 ℃以内温度环境下具有良好的抗氧化能力;5～6个300～1 000 ℃热循环内涂层试样氧化速率下降,其后增加,6 h内经过10次300～1 000 ℃热循环后涂层试样氧化失重为19.64%,涂层在一定热循环范围内具有抗热震性能.SiC结合B基陶瓷为主要组分的涂层能够在较长氧化时间和一定的热震循环周期内保持涂层试样较低的氧化失重率并降低其氧化速率.