Electroreduction of Oxygen and Electrooxidation of Methanol at Carbon and Single Wall Carbon Nanotube Supported Platinum Electrodes

The present research aimed at investigating the electrocatalytic properties and the electrochemical deposition of Pt nanoparticles on carbon powder, carbon nanotube and preparation of carbon and single wall carbon nanotube supported platinum electrodes. The Pt nanoparticles were synthesized by electroreduction of hexachloroplatinic acid in aqueous solution at ?200 mV. Electrocatalytic properties of the modified electrodes for oxygen reduction were investigated by cyclic voltammetry in O₂ saturated solution containing 0.1 M HClO₄. Methanol electrooxidation at the modified surfaces in 0.5 M HCLO₄ was studied by cyclic voltammetry. The corresponding results showed that the Pt/SWCNT/GC electrode exhibits more improved catalytical activity than the Pt/C/GC electrode.     

Synthesis of Carbon Quantum Dots Nanoparticles by Cyclic Voltammetry and Its Application as Methanol Tolerant Oxygen Reduction Reaction Electrocatalyst

Carbon quantum dot (CQD) nanoparticles are synthesized by one‐step electrochemical method, cyclic voltammetry (CV), at different potentials using graphite rods and NaOH/EtOH as electrolyte. The electro‐chemically manufactured CQD is characterized by Transmission electron microscopy, Ultra violet absorption, X‐ray diffraction and Fourier transform infrared spectrometry. The morphology and microstructure methods confirm the formation of high quality CQD. Finally, we design a new gas diffusion electrode (GDE) based on CQD pasted on carbon paper for the oxygen reduction reaction at cathode side as methanol tolerance in direct methanol fuel cell and compared it with standard Pt‐C catalysts using cyclic voltammetry and linear sweep voltammetry. The ORR results in presence of methanol indicate that the GDE prepared from CQD exhibits methanol tolerance compared to the GDE prepared from Pt/C (Electrochem).     

甲醇对炭载铂和四羧基酞菁钴催化氧还原动力学的影响

运用旋转圆盘电极技术和线性扫描伏安方法研究比较了甲醇对炭载铂（Pt/C）和800 ℃热处理的炭载四羧基酞菁钴（CoPcTc/C）催化氧还原动力学的影响.结果表明，对于Pt/C催化剂，在大于0.64 V和小于0.18 V（vs SCE）的电位范围，甲醇的氧化和氧的还原互不影响，而在其它电位范围，甲醇使Pt/C催化氧还原的性能严重降低.对于800 ℃热处理的CoPcTc/C，在整个电位范围内，甲醇的存在对氧还原都没有影响，是一种活性较高、耐甲醇能力强的氧还原电催化剂.     

Carbon Aerogels Supported Pt Nanoparticles as Electrocatalysts for Methanol Oxidation in Alkaline Media

Carbon aerogels (CAs) were prepared by sol‐gel polycondensation of resorcinol and formaldehyde with BET surface area of 616 m² g^?1 and the average pore size of 9.8 nm. The prepared CAs were used as supports for Pt nanoparticles for methanol oxidation in alkaline media. In comparison with Pt supported on commercial Vulcan XC‐72R carbon (Pt/C) electrocatalysts, Pt supported on CAs (Pt/CAs) electrocatalysts exhibited higher peak current density and more negative onset potential toward methanol oxidation. The effects of different parameters such as NaOH concentration, methanol concentration, and scan rate on the methanol oxidation reaction were investigated in detail. The results showed that the Pt/CAs electrocatalysts had promising application for methanol oxidation in alkaline media.     

Au@Pt纳米粒子催化O2还原反应的电化学研究

以100 nm的Au粒子为核,抗坏血酸为还原剂,H2PtCl6·6H2O为前驱体,合成了Pt包Au核壳结构纳米粒子( Au@ Pt)及其修饰的玻碳(GC)电极(Au@ Pt/GC).采用旋转圆盘电极等常规电化学方法,比较了Au@ Pt/GC和商用碳载铂(Pt/C)修饰的玻碳电极(Pt/C/GC)催化O2还原反应活性及耐甲醇性能,发现Au@ Pt纳米粒子在铂用量很低的情况下,其催化O2还原反应活性仍与商用Pt/C相当,而且还具有优良的耐甲醇性能;其催化O2还原反应机理按O2直接还原成H2O的四电子历程进行.     

Electrocatalytic Reduction of Oxygen at Multi‐Walled Carbon Nanotubes and Cobalt Porphyrin Modified Glassy Carbon Electrode

The multi‐walled carbon nanotubes (MWNTs) modified glassy carbon electrode exhibited electrocatalytic activity to the reduction of oxygen in 0.1 M HAc‐NaAc (pH 3.8) buffer solution. Further modification with cobalt porphyrin film on the MWNTs by adsorption, the resulted modified electrode showed more efficient catalytic activity to O₂ reduction. The reduction peak potential of O₂ is shifted much more positively to 0.12 V (vs. Ag/AgCl), and the peak current is increased greatly. Cyclic voltammetry (CV), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), were used to characterize the material and the modified film on electrode surface. Electrochemical experiments gave the total number of electron transfer for oxygen reduction as about 3, which indicated a co‐exist process of 2 electrons and 4 electrons for reduction of oxygen at this modified electrode. Meanwhile, the catalytic activities of the multilayer film (MWNTs/CoTMPyP)_n prepared by layer‐by‐layer method were investigated, and the results showed that the peak current of O₂ reduction increased and the peak potential shifted to a positive direction with the increase of layer numbers.     

Pt 纳米颗粒在聚二甲基二烯丙基氯化铵功能化碳纳米管上的自发沉积及其对甲醇的电氧化性能

利用聚二甲基二烯丙基氯化铵(PDDA)非共价修饰的碳纳米管(CNTs)与PtCl₆^2-之间的自发氧化还原作用, 制备了Pt 纳米颗粒(Pt NPs)/CNTs-PDDA复合催化剂. PDDA在该催化剂中具有三种作用: (1) 作为金属前驱体PtCl₆^2-还原为Pt NPs 的还原剂; (2) 作为原位产生的Pt NPs 的稳定剂; (3) 在CNTs 表面形成保护膜抑制CNTs 在甲醇电催化氧化过程中的腐蚀. 采用傅里叶变换红外(FTIR)光谱、热重分析和拉曼光谱对CNTs-PDDA进行了表征, 表明PDDA通过π-π作用已成功覆盖在CNTs 表面, 并且修饰过程没有导致CNTs 结构的破坏. 采用透射电子显微镜(TEM)对Pt NPs/CNTs-PDDA 催化剂进行了表征, 结果表明, Pt NPs 均匀地分散在CNTs上, 平均粒径约2 nm, 且粒径分布范围窄. 用循环伏安法、计时电流法进一步考察了Pt NPs/CNTs-PDDA催化剂在酸性介质中对甲醇的电催化氧化的性能. 电化学测试结果表明, 与原始CNTs 负载的Pt NPs催化剂相比,Pt NPs/CNTs-PDDA催化剂具有更高的电化学活性表面积、电催化质量比活性和稳定性.     

聚合物膜燃料电池用电催化剂研究进展

综述了聚合物膜燃料电池（ＰＥＭＦＣ）用电催化剂最新的研究进展,包括阳极甲醇催化剂有机螯合物催化剂及其它的还原催化剂。     

Electrochemically Co‐deposited Teeth‐like Virus‐Platinum Nanohybrids as an Electrocatalyst for Methanol Oxidation Reaction

M13 virus (M13) as scaffolds has a major appeal, owing to their mono‐dispersed, fibrillar morphology and engineerable surface reactive sites. Herein we had developed a facile electrocatalyst for energy application. Platinum nanostructures are directly co‐deposited from a wild‐type M13 (or) two different engineered M13 mixed electrolytes onto the ITO electrodes. The engineered M13 with 4E peptides could specifically nucleate Pt precursor thereby enables the efficient growth of teeth‐like structures at the ITO electrode. The electrocatalytic activity of the resulting electrocatalyst toward methanol oxidation in alkaline medium was investigated and found enhanced mass activity (0.321 A/mg_Pt) relative to the catalyst prepared from wild‐type M13, Y3E peptides engineered M13 and without M13. Our novel electrocatalyst fabrication can be extended to other metal and metal oxides and its application might be useful to develop novel clean and green energy generating and storage materials.     

利用原位红外光谱与微分电化学质谱联用技术研究在Pt以及PtRu电极上发生的甲醇氧化反应

利用电化学衰减全反射原位傅里叶变换红外光谱与微分电化学质谱联用技术,在流动电解池环境以及恒电位条件下研究了Pt电极和Pt电极通过表面电沉积Ru形成的PtRu电极（PtxRuy）上发生的甲醇氧化反应（反应电解质溶液为0.1 mol/L HClO4＋0.5 mol/L MeOH）. 在0.3-0.6 V（参比电极为可逆氢参比）实验用到的所有电极上,CO是唯一能从红外光谱观察到的与甲醇相关的表面吸附物;在Pt0.56Ru0.44电极上可以观察到CO吸附在Ru原子形成的岛上和CO线式吸附在Pt电极表面红外波段,而其他电极上只能观察到Pt表面上线式吸附的CO;甲醇氧化活性按Pt0.73Ru0.27〉Pt0.56Ru0.44〉Pt0.83Ru0.17〉Pt的顺序递减;在0.5V时,甲醇在Pt0.73Ru0.27电极上的氧化反应的CO2电流效率达到了50%.     

Self‐Assembled Platinum Nanoflowers on Polydopamine‐Coated Reduced Graphene Oxide for Methanol Oxidation and Oxygen Reduction Reactions

The morphology‐ and size‐controlled synthesis of branched Pt nanostructures on graphene is highly favorable for enhancing the electrocatalytic activity and stability of Pt. Herein, a facile approach is developed for the efficient synthesis of well‐dispersed Pt nanoflowers (PtNFs) on the surface of polydopamine (PDA)‐modified reduced graphene oxide (PDRGO), denoted as PtNFs/PDRGO, in high yield. The synthesis was performed by a simple heating treatment of an aqueous solution that contained K₂PtCl₄ and PDA‐modified graphene oxide (GO) without the need for any additional reducing agent, seed, surfactant, or organic solvent. The coated PDA serves not only as a reducing agent, but also as cross‐linker to anchor and stabilize PtNFs on the PDRGO support. The as‐prepared PtNFs/PDRGO hybrid, with spatially and locally separated PtNFs on PDRGO, exhibits superior electrocatalytic activity and stability toward both methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) in alkaline solutions.     

Biaxially-Strained Phthalocyanine at Polyoxometalate@Carbon Nanotube Heterostructure Boosts Oxygen Reduction Catalysis

Iron phthalocyanine (FePc) with unique FeN₄ site has attracted increasing interests as a promising non-precious catalyst. However, the plane symmetric structure endows FePc with undesired catalytic performance toward the oxygen reduction reaction (ORR). Here, we report a novel one-dimensional heterostructured ORR catalyst by coupling FePc at polyoxometalate-encapsulated carbon nanotubes (FePc-{PW₁₂}@NTs) using host-guest chemistry. The encapsulation of polyoxometalates can induce a local tensile strain of single-walled NTs to strengthen the interactions with FePc. Both the strain and curvature effects of {PW₁₂}@NT scaffold tune the geometric structure and electronic localization of FeN₄ centers to enhance the ORR catalytic performance. As expected, such a heterostructured FePc-{PW₁₂}@NT electrocatalyst exhibits prominent durability, methanol tolerance, and ORR activity with a high half-wave potential of 0.90 V and a low Tafel slope of 30.9 mV dec⁻¹ in alkaline medium. Besides, the assembled zinc-air battery demonstrates an ultrahigh power density of 280 mW cm⁻², excellent charge/discharge ability and long-term stability over 500 h, outperforming that of the commercial Pt/C+IrO₂ cathode. This study offers a new strategy to design novel heterostructured catalysts and opens a new avenue to regulate the electrocatalytic performance of phthalocyanine molecules.     

Preparation of Surfactant-Free Pt and PtRu Nanoparticles with High Activity for Methanol Oxidation

A simple and green approach to synthesize highly active electro-catalysts for methanol oxi- dation reaction （MOR） without using any organic agents is described. Pt nanoparticles are directly deposited on the pre-cleaned and pre-oxidized multiwall carbon nanotubes （MWC- NTs） from Pt salt by using CO as the reductant. MOR activity has been characterized by both cyclic voltammetry and chronoamperometry, the current density and mass specific current at the peak potential （ca. 0.9 V vs. RHE） reaches 11.6 mA/cm^2 and 860 mA/mgpt, respectively. After electro-deposition of Ru onto the Pt/MWCNTs surface, the catalysts show steady state mass specific current of 20 and 80 mA/mgpt at 0.5 and 0.6 V, respectively.     

Probing the Pt Surface for Oxygen Reduction by Insertion of Ag

We report on the probing of the Pt surface for oxygen reduction reaction (ORR) by insertion of Ag. Therefore, PtAg bimetallic nanoparticles were prepared by pulse electrodeposition. In a second step, Ag was electro‐dissolved in acidic media from the particles under formation of Pt skeleton. The ORR activity of these Pt skeleton depends on two factors: (1) on the surface properties of the Pt‐shell and (2) on the electronic as well as geometric influences of the remaining Ag in the particle core. By varying the conditioning procedure prior to measuring the ORR activity, we were able to differentiate between these two effects.     

生物质基碳材料作为氧还原反应催化剂的研究进展

燃料电池作为一种清洁能源有很大的发展前景,其阴极氧还原反应多采用铂基催化剂,但由于贵金属铂的储量稀少、价格昂贵等原因,严重阻碍了燃料电池的商业化进程。寻找高活性、高稳定性的新材料来替代阴极铂基催化剂成为燃料电池大规模商业化亟待解决的关键问题之一。研究表明,以生物质为原料的碳材料有望成为商业铂基氧还原催化剂的一种理想替代品。本文综述了这方面的研究进展,并且展望了未来的发展趋势。     

铂微粒修饰的氧化钛电极对甲醇的电催化氧化性能

直接甲醇质子交换膜燃料电池(DMPEMFC)可用作未来电动车辆的动力电源,但要达到实际应用还有大量问题有待进一步解决.目前限制DMPEMFC实际应用的主要问题是甲醇阳极氧化催化剂低的活性、高的价格及催化剂的毒化.     

Pt/纳米碳管空气电极氧还原反应的电催化性能

以不同质量比的铂、纳米碳管、活性炭为催化层制备空气电极并测定其稳态极化曲线和交流阻抗.研究发现,纳米碳管经硝酸处理后其氧还原反应性能得到提高,特别是将表面氧化后再沉积Pt,对氧的电还原反应影响更显著.以质量比4∶1的活性炭/纳米碳管载Pt制备的空气电极,在过电位ηc为500～600mV下,氧还原电流可达600～700mA·cm-2.EIS测试表明,纳米碳管载Pt后的欧姆极化阻抗和电化学阻抗均非常小.     

Pt／C气体扩散电极制备方法的探索

Ｐｔ／Ｃ气体扩散电极制备方法的探索马永林（青海教育学院,青海,西宁８１０００８）以Ｐｔ／Ｃ为电催化剂的气体扩散电极的制备方法是直接影响该电极电化学性能的重要因素。一般的制备方法是基于将Ｐｔ／Ｃ电催化剂和聚四氟乙烯以及某些有机物或表面活性剂的糊状物涂布...     

Pd/Pt二元合金电极的制备及氧还原性能

本文利用欠电位沉积亚单层的Cu及Pt置换取代Cu的方法, 制备了具有不同表面元素组成的Pd/Pt二元合金电极(用Pd/Ptx表示, x指欠电位沉积Cu-Pt置换取代Cu过程的次数),并对其表面元素组成、氧还原性能进行了表征. 在控制欠电位沉积Cu的下限电位恒定(0.34 V)的前提下, 表面Pt/Pd的元素组成比通过重复欠电位沉积Cu及Pt置换取代Cu的次数(1~5次)来可控地调变. 光电子能谱(XPS) 以及红外光谱实验表明,Pd/Ptx电极表层区的Pt：Pd元素组成比随着Pt沉积次数增加而增加, 对Pd/Pt4电极, 在电极表层区约2~3 nm内的Pt/Pd的原子比大约是1:4,而最表层裸露Pd原子的比例仍在20%以上。循环伏安结果显示, 随着Pt沉积次数的增加(1-5次), Pd/Ptx电极表面越不易被氧化。氧还原测试结果显示随着Pt沉积次数的增加(1~4次), Pd/Ptx二元金属电极的氧还原活性依次增加, 经过第3次沉积后其氧还原活性已优于纯Pt,而经4次以上沉积,其氧还原活性基本不变。在其它反应条件相同条件的前提下, Pd/Pt4电极上氧还原的半波电位与纯Pt相比右移约25 mV。结合本文与文献的实验结果,我们初步认为Pd/Ptx二元金属体系氧还原性能改善主要源自表层Pd原子导致其邻近的Pt原子上含氧物种吸附能的降低.     

铂/石墨烯氧还原电催化剂的共还原法制备及表征

使用硼氢化钠共还原法制备40% (w)铂/石墨烯电催化剂用于氧还原反应. 通过循环伏安测试发现, 这种方法制备所得铂/石墨烯催化剂对氧还原反应活性较铂/碳催化剂差, 但稳定性有所提高. 在稳定性测试中,铂/石墨烯电催化性能衰减为50%, 较铂/碳(79%)好. X射线衍射(XRD)和透射电子显微镜(TEM)表征发现在铂/石墨烯催化剂中两者存在明显交互作用, 这可能是阻止石墨烯再堆垛和防止铂颗粒团聚的主要原因. 通过对单电池性能测试也发现铂/石墨烯催化剂更有利于电池长期稳定.