炭气凝胶负载PtRu纳米颗粒用作甲醇氧化催化剂

采用乙二醇还原法制备了以炭气凝胶(CA)为载体的PtRu纳米颗粒催化剂.透射电镜(TEM)观察得知:PtRu的粒径为3nm左右,且在载体CA表面均匀分散.循环伏安和恒电位测试表明:催化剂的甲醇氧化启动电位和载体的孔结构没有明显依赖关系.以平均孔径较大的炭气凝胶为载体制备的催化剂拥有较高的甲醇氧化催化活性.可以认为催化剂活性的差异主要是由其不同的传质性能决定的.甲醇在较大的孔中扩散比较快,更容易到达PtRu颗粒的表面,从而提高了贵金属Pt的利用效率.     

Pt/ZrP-Th-CNTs复合催化剂的制备及其对甲醇的电催化氧化

利用硫堇(Th)和碳纳米管(CNTs)对磷酸锆(ZrP)改性,并以改性的ZrP复合材料作为催化剂载体,采用化学还原法制备得到Pt/ZrP-Th-CNTs复合催化剂.SEM研究结果表明,金属铂(Pt)微粒在载体表面具有很高的分散度,且颗粒大小均匀,电极的比表面积也得到较大提高.考察了复合电极在酸性介质中对甲醇的电催化氧化...     

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。     

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.     

(Pt/Sn)-碳纳米管复合物的电催化性能

以碳纳米管(Carbon nanotubes,CNTs)为载体、乙二醇和甲酸钠为还原剂,采用浸渍法制备了不同Pt/Sn原子比的(Pt/Sn)-CNT复合物.通过X-射线衍射(XRD)和透射电子显微镜(TEM)对碳纳米管负载金属颗粒过程中的显微结构变化进行了研究.结果表明:Pt、Sn粒子在碳纳米管上高度分散,粒径分布在3.5nm～6.5nm之间,Sn元素以Pt-Sn合金和SnO2结构存在.循环伏安(CV)测试表明:Pt/Sn原子比为2.5:1～3.5:1时,(Pt/Sn)-CNT复合物的催化活性和抗毒化能力最佳.(Pt/Sn)-CNT复合物中CNTs保持了完整结构,对Pt、Sn粒子起到了稳定性作用,有利于提升(Pt/Sn)-CNT复合物对甲醇的氧化活性.     

Pt/C催化剂制备及CO催化氧化性能研究

采用大气压介质阻挡放电辅助氢气热还原方法和氢气热还原方法制备Pt/C催化剂,考察了制备方法及Pt负载量对Pt/C催化性能的影响。采用X-射线衍射(XRD)、循环伏安法、CO催化氧化反应研究Pt/C催化剂的晶相结构、电催化性能和CO催化氧化活性。结果表明:大气压介质阻挡放电辅助氢气热还原所制备的样品具有更高的电化学活性和CO催化氧化活性。当Pt负载量在2%到10%之间变化时,Pt/C-PC催化活性随负载量增加而增加。XRD测试结果显示当Pt负载量为2%,5%和10%时,Pt粒径分别为:10.6 nm,9.1 nm和6.4 nm,说明采用等离子体辅助氢气热还原方法制备的Pt/C-PC催化剂,Pt负载量越大,Pt粒径越小,CO催化氧化活性更高。     

Pt/TiO2-NTs复合材料的制备及其甲醇电氧化机理研究

采用水热法合成锐钛矿型TiO2纳米管(TiO2-NTs),并以其为载体制备了Pt/TiO2-NTs复合材料。用TEM、XRD对复合材料的形貌和结构进行了表征,TEM测试表明Pt纳米粒子以簇状形式均匀地分散在TiO2纳米管表面。运用循环伏安法研究了Pt/TiO2-NTs复合材料在不同条件下对硫酸中甲醇的电催化活性,并讨论了甲醇的电氧化机理。结果表明,Pt/TiO2-NTs复合材料具有出色的电催化活性。因此,TiO2-NTs被认为是非常有潜力的燃料电池贵金属催化剂载体材料。     

载体表面化学状态对Pt/C催化剂结构及电催化活性的影响

对碳黑进行不同条件的氧化处理得到不同表面化学状态的载体,以甲醛为还原剂,氯铂酸为前驱体,制备Pt/C电催化剂.运用X射线光电子能谱(XPS)、X射线衍射(XRD)、透射电镜(TEM)等分析手段研究碳黑及Pt/C催化剂的化学组成、化学状态、晶体结构及表面形貌,并用循环伏安法(CV)测试Pt/C催化剂对甲醇的电催化氧化.结...     

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.     

利用层间化合物制备载Pt催化剂

通过利用Pt(IV)-GICs和Pt(IV)乙炔黑层间化合物来制备应用于甲醇电氧化石墨和乙炔黑载铂催化剂。具体过程如下在惰性气氛下,利用H     

质子交换膜燃料电池中碳纳米管负载的氧电极材料制备与表征

本文介绍了碳纳米管(CNTs)在质子交换膜燃料电池催化剂中的应用,对Pt/CNTs及Pt/C催化剂的比表面积、孔径、孔分布及金属表面分散情况进行了比较.实验发现,具备典型中孔结构的CNTs使得铂金属在其表面分散更加均匀.在催化剂制备工艺的研究中发现,合适的硝酸(40%)处理会使催化剂载体具备更加适宜的孔结构.通过本文的讨论,可以认为Pt/CNTs是一种可以应用在质子交换膜燃料电池上很有前景的电催化剂.     

PEMFC膜电极电催化层的制备和性能

膜电极催化层的组成和电催化剂的活性对质子交换膜燃料电池的性能有很大影响．采用浸渍还原法制备出了Pt平均粒径为3．1nm的Pt／C催化剂．催化剂中Pt的粒径和在碳黑载体（VulcanXC-72）表面的分散程度采用透射电镜（TEM）进行测试．用Pt／C催化剂、适量的Nation溶液和PrFE乳液制备出质子交换膜燃料电池（PEMFc）膜电极的催化剂层,并研究了该催化剂层中PTFE含量对其性能的影响．实验表明,PTFE强烈的疏水性可以迫使部分水分向阳极反扩散,催化层中加入适量的PTFE可以使膜电极具有一定的水管理能力,在去掉辅助增湿系统的条件下具有良好的极化性能．     

新型碳材料质子交换膜燃料电池Pt催化剂载体的研究进展

质子交换膜燃料电池(PEMFC)具有能量转换效率高、功率密度大、室温启动快、噪音低和零污染等特点, 有望减少二氧化碳排放量, 缓解能源危机, 在轨道交通、航空航天等领域具有广阔的应用前景。催化剂是PEMFC的关键材料, Pt催化氧还原反应活性和稳定性好, 是广泛使用且很难被取代的电催化剂。然而Pt储量低、价格昂贵, 导致PEMFC成本较高, 使用Pt载体可减少PEMFC的Pt负载量, 提高Pt利用率。碳材料具有成本低廉、比表面积大、孔结构丰富、电导率和表面性质可调等特性, 是广泛应用的Pt载体。商用的炭黑载体对Pt的利用效率低, 抗电化学腐蚀性较差。为了进一步提高PEMFC的性能和持续性, 需要研发能够均匀负载Pt、高效利用Pt、抗电化学腐蚀性强且导电性好的碳载体, 进而实现PEMFC的大规模应用。炭气凝胶、碳纳米管和石墨烯等新型碳载体具有独特的结构和性质, 可以提高PEMFC性能和寿命, 引起了研究者的广泛关注。本文对近年来PEMFC新型碳材料Pt载体的研究进展进行了较为详细的综述, 并对其发展趋势作出了适当评论。     

Carbon-supported platinum catalysts for on-site hydrogen generation from NaBH4 solution

A flexible hydrogen generation (HG) method based on catalytic hydrolysis of NaBH₄ solution is developed. Carbon-supported platinum (Pt/C) samples served as the catalysts, and the catalytic strategies for hydrolysis of NaBH₄ solution are analyzed via the studies on apparent morphology, catalytic activity, BET surface, and sustaining H₂ supply test. Pt/C catalysts are proved to be excellent accelerators, and Pt-loading plays an important role in the hydrogen generation reactions. For a reactor loaded with 100 mg 13.1% Pt/C catalyst, when 10% NaBH₄–5% NaOH solution is pumped into the reactor with a speed of 10 ml/min, it can achieve a maximum HG rate of 29.6 (l/min/g catalyst), and give sustaining H₂ supply for a proton exchange membrane fuel cell (PEMFC) with an average HG rate of 23.0 (l/min/g catalyst).     

Preparation and characterization of PtRu nanoparticles supported on nitrogen-doped porous carbon for electrooxidation of methanol

N-doped porous carbon nanospheres (PCNs) were prepared by chemical activation of nonporous carbon nanospheres (CNs), which were obtained via carbonization of polypyrrole nanospheres (PNs). The catalysts, PtRu and Pt nanoparticles supported on PCNs and Vulcan XC-72 carbon black, were prepared by ethylene glycol chemical reduction. Transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy were employed to characterize samples. It was found that PCNs containing N function groups possess a large number of micropores. Uniform and well-dispersed Pt and PtRu particles with narrow particle size distribution were observed. The electrooxidation of liquid methanol on these catalysts was investigated at room temperature by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy (EIS). The results showed that alloy catalyst (Pt(1)Ru(1)/PCN) possessed the highest catalytic activity and better CO tolerance than the other PtRu and Pt-only catalysts; PtRu nanoparticles supported on PCN showed a higher catalytic activity and more stable sustained current than on carbon black XC-72. Compared to commercial Alfa Aesar PtRu catalyst, Pt(1)Ru(1)/PCN reveals an enhanced and durable catalytic activity in methanol oxidation because of the high dispersion of small PtRu nanoparticles and the presence of N species of support PCNs.     

Preparation of a platinum electrocatalyst by coaxial pulse arc plasma deposition

We have developed a new method of preparing Pt electrocatalysts through a dry process. By coaxial pulse arc plasma deposition (CAPD), highly ionized metal plasma can be generated from a target rod without any discharged gases, and Pt nanoparticles can be deposited on a carbon support. The small-sized Pt nanoparticles are distributed over the entire carbon surface. From transmission electron microscopy (TEM), the average size of the deposited Pt nanoparticles is estimated to be 2.5 nm, and their size distribution is narrow. Our electrocatalyst shows considerably improved catalytic activity and stability toward methanol oxidation reaction (MOR) compared with commercially available Pt catalysts such as Pt black and Pt/carbon (PtC). Inspired by its very high efficiency toward MOR, we also measured the catalytic performance for oxygen reduction reaction (ORR). Our PtC catalyst shows a better performance with half-wave potential of 0.87 V, which is higher than those of commercially available Pt catalysts. The higher performance is also supported by a right-shifted onset potential. Our preparation is simple and could be applied to other metallic nanocrystals as a novel platform in catalysis, fuel cells and biosensors.     

Synthesis of core–shell-structured SBA-15@MgAl2O4 with enhanced catalytic performance of propane dehydrogenation

Core–shell-structured SBA-15@MgAl₂O₄ (abbreviated as S@MA) was prepared by homogeneous precipitation through sol–gel method. The effects on the properties of S@MA as a supporting material have been investigated in comparison with MA and SBA-15. The results showed that the pore structure was changed, the acid sites were introduced, and the surface properties were improved by the construction of the core-shell-structured S@MA. Then, these materials were used as the carrier for the catalysts by impregnation method. Moreover, in PtSnNa/S@MA, these modifications not only decreased the size of surface Pt ensembles, but also changed the interfacial character between metal and support. In addition, compared to PtSnNa/MA, the capacity of the catalyst which supports on S@MA to accommodate coke was improved and the carbon deposit on PtSnNa/S@MA was migrated from the active metal to the carrier. These intriguing results are attributed to larger surface area and the appearance of the acid sites in S@MA.     

Electrocatalytic activity of Pt nanoparticles supported on novel functionalized reduced graphene oxide-chitosan for methanol electrooxidation

Here, graphene oxide (GO) was synthesized by a modified Hummers’ method and was functionalized with 1,1′-dimethyl-4,4′-bipyridinium dichloride (MV) accompanied by chitosan (CH) to prepare a novel MV-RGO-CH support. Pt/MV-RGO-CH catalyst was prepared by immobilization of the Pt nanoparticles on MV-RGO-CH support. The microstructure and morphology of the prepared catalyst was characterized by transmission electron microscopy and X-ray powder diffraction analysis. The electrocatalytic activity of Pt/MV-RGO-CH catalyst was investigated for methanol electrooxidation through cyclic voltammetry (CV), CO_ads stripping voltammetry, chronoamperometry, and electrochemical impedance spectroscopy (EIS) techniques. The effects of some experimental factors for methanol electrooxidation such as methanol concentration, scan rate and temperature were studied at the prepared catalyst. Durability of the catalyst was also investigated. Comparing the catalytic activity of the Pt/MV-RGO-CH nanocatalyst with Pt/CH and Pt/MV-RGO catalysts indicated that Pt/MV-RGO-CH has a very good catalytic activity for methanol electrooxidation.     

PEMFC用抗溺水性功能化Pt/C催化剂的制备及表征

催化剂的碳载体腐蚀是Pt/C催化剂催化性能下降的重要原因,并且亲水性的催化剂增加了质子交换膜燃料电池氧电极发生水淹的风险。利用过氧化氢对XC-72碳进行氧化预处理,负载Pt后,进一步用水合肼对Pt/C催化剂还原,制备耐蚀性和抗溺水性的Pt/C催化剂。对红外光谱吸收峰进行比较可知,经双氧水处理后,XC-72碳表面的含氧官能团数量增加,其接触角小于未经处理的XC-72碳;进一步用水合肼还原氧化后的XC-72碳,接触角较氧化的XC-72碳增大22.4°,抗溺水性增强。由比表面积测定可知,双氧水处理XC-72碳,比表面积下降,但中孔比例增加,有利于Pt的负载。水合肼还原后的Pt/C催化剂较还原之前的Pt/C催化剂抗溺水性增强,接触角增大6.2°。经2000周次循环伏安扫描,水合肼还原后的Pt/C催化剂电化学比表面损失减小,耐久性提高。     

掺磷非晶氧化钛负载铂用于高效催化氧化挥发性有机化合物

高活性催化剂是挥发性有机化合物(VOCs)催化氧化消除的关键因素。本研究通过简单的共沉淀法成功制备了具有高比表面积的非晶介孔磷掺杂氧化钛负载铂催化剂(Pt/ATO-P)。通过P掺杂, 既可获得非晶介孔结构, 又可获得高ATO-P比表面积(可达278.9 m²·g^-1)。非晶介孔Pt/ATO-P催化剂显示出优异的VOCs催化氧化性能和良好的热稳定性。Pt/ATO-P样品在空速为36000 mL·h^-1·g^-1、甲苯浓度为10000 mL·m^-3的反应条件下, 对甲苯催化氧化的T₅₀和T₉₀(实现50%和90%转化率所需的温度)分别为130 ℃和140 ℃, 明显优于无磷催化剂Pt/TiO₂。这些发现可以为拓展非晶介孔磷化材料在环境净化和能源转化等领域的应用提供重要参考。