乙醇在Pt/nanoTiO2-CNT复合催化剂上的电催化氧化

通过前驱体Ti(OEt)4直接水解和电化学扫描电沉积法制备在Ti基体上的纳米TiO2-碳纳米管复合膜载Pt(Pt/nanoTiO2-CNT)复合催化剂. 透射电镜 (TEM) 和X射线衍射 (XRD) 结果表明, 锐钛矿型纳米TiO2粒子和Pt纳米粒子(粒径均为5~10 nm)均匀地分散在碳纳米管表面. 通过循环伏安和计时电流法研究表明, Pt/nanoTiO2-CNT 复合催化剂(Pt载量为0.32 mg•cm−2) 具有高达51.8 m2•g−1的电化学活性比表面积, 常温常压下对乙醇的电化学氧化具有高催化活性和稳定性, 乙醇氧化峰电位分别为0.59、0.96和0.24 V, 氧化峰电流密度分别达到−115、−113和−75 mA•cm−2. 复合催化剂对乙醇电氧化的高催化活性可归因于nanoTiO2、CNT和Pt纳米粒子的协同催化作用.     

MoP-NC纳米球负载Pt纳米粒子用于高效甲醇电解

实现绿色甲醇电解制氢需要高效的双功能催化剂。本文采用热处理结合乙二醇还原法成功制备了MoP-NC纳米球负载的超细Pt纳米粒子(平均粒径为2.53 nm)复合催化剂(Pt/MoP-NC)用于高效甲醇电解制氢。MoP-NC纳米球不仅能提高Pt纳米粒子的分散性并且增强Pt的抗中毒能力。电化学测试表明Pt/MoP-NC催化剂在酸性甲醇氧化反应(MOR)和析氢反应(HER)中具有较高的催化性能;其中,MOR的正向扫描峰值电流密度为90.7 mA∙cm⁻²,是商业Pt/C催化剂的3.2倍,在10 mA∙cm⁻²的电流密度下,HER的过电位低至30 mV,与商业Pt/C接近。由Pt/MoP-NC||Pt/MoP-NC组装的两电极电解槽驱动10 mA∙cm⁻²的电流密度仅需要0.67 V的电压,比相同条件下电解水的电压低1.02 V,大大降低了能量输入。Pt/MoP-NC的高催化性能主要来源于Pt活性中心与相邻层状多孔球形结构的MoP-NC载体之间电子效应及配体效应引起的抗一氧化碳中毒能力的提升和含氧物种的容易生成。     

调制脉冲电沉积法制备质子交换膜燃料电池铂催化电极

通过调制脉冲电流在质子交换树脂(Nafion)粘接的无催化多孔碳电极(UCE)上电沉积Pt 催化剂, 对所沉积Pt 催化电极性能及负载量用循环伏安法(CV)、X 射线衍射仪(XRD)、透射电镜(TEM)及分光光度法进行了表征. 结果表明, 通过调制电沉积过程的脉冲参数, 能够实现质子交换膜燃料电池(PEMFC)电极Pt催化剂的直接电化学沉积, 能够调控电沉积Pt粒径, 并能有效地缓解电沉积过程中析氢对沉积金属催化剂铂的干扰, 所沉积的Pt 催化剂利用率较传统Nafion 粘接Pt/C催化电极要高. 脉冲导通时间ton 为300 μs、断通时间toff 为1200 μs, 脉冲峰值电流密度jp 为100 mA·cm-2 时, 电沉积120 s制得的电极的Pt 晶粒约5-8 nm, Pt 表面利用率为43.14%, 沉积Pt的电流效率为45%.     

多壁碳纳米管负载Pt-Au电催化剂的微波合成及其催化氧还原性质

采用微波还原法合成了具有较小的纳米颗粒以及较高的分散程度的纳米Pt-Au复合多壁碳纳米管(Pt-Au/MWCNTs)电催化剂. 利用旋转圆盘电极(RDE)技术对Pt-Au/MWCNTs电催化剂在0.1 mol•L−1 HClO4溶液中的催化氧还原的动力学进行了研究. 结果表明, Pt和Au的质量比为1:2时, 表现出对氧气较好的催化还原活性.     

氧化钒/多孔硅/硅结构的微观形貌、纳米力学及温敏特性

采用电化学腐蚀法在硅基片表面形成多孔硅, 利用直流对靶反应磁控溅射方法在不同电流密度条件下制备的多孔硅样品表面上溅射沉积了VOx薄膜, 获得了氧化钒/多孔硅/硅(VOx/PS/Si)结构. 采用场发射扫描电镜(FESEM)观测多孔硅及VOx/PS/Si结构的微观形貌, 采用纳米压痕仪器测量VOx/PS/Si结构的纳米力学特性, 通过电阻-功率曲线分析研究其温度敏感特性. 实验结果表明, 在40和80 mA·cm-2电流密度下制备多孔硅的平均孔径分别为18和24 nm, 用显微拉曼光谱法(MRS)测量其热导率分别为3.282和1.278 kW·K-1; VOx/PS/Si结构的电阻随功率变化的平均速率分别为60×10⁹和100×10⁹ Ω·W-1, VOx/PS/Si结构的显微硬度分别为1.917和0.928 GPa. 实验结果表明, 多孔硅的微观形貌对VOx/PS/Si结构的纳米力学及温敏特性有很大的影响, 大孔隙率多孔硅基底上制备的VOx/PS/Si 结构比小孔隙率多孔硅基底上制备的具有更高的温度灵敏度, 但其机械稳定性也随之下降.     

Pt纳米粒子/Pd纳米线复合材料对乙醇的电催化氧化研究

采用恒电位法在多孔阳极氧化铝模板中电沉积Pd纳米线阵列,再运用循环伏安法在Pd纳米线阵列表面沉积Pt纳米粒子制备出复合纳米材料电极。运用循环伏安法和计时电流法研究了该复合纳米材料电极对乙醇的电催化性能的影响。结果表明,Pt纳米粒子/Pd纳米线复合电极相比于单独的Pd纳米线电极或Pt纳米粒子电极,对乙醇氧化有更高的电催化活性和很好的稳定性。     

乙二醛在Ti/纳米TiO2-Pt修饰电极上的电催化氧化

采用溶胶-凝胶和电沉积法制备Ti基纳米TiO2-Pt(Ti/纳米TiO2-Pt)修饰电极. X射线衍射(XRD)表明纳米TiO2为锐钛矿型, 扫描电镜(SEM)显示Pt纳米粒子在纳米TiO2多孔膜的表面呈现簇分散状态, 平均粒径约25 nm. 通过循环伏安(CV)和计时电流法研究了Ti/纳米TiO2-Pt修饰电极对乙二醛直接电氧化的电催化活性, 结果表明, 修饰电极对乙二醛的直接电氧化呈现良好的催化活性, 在0.60和1.23 V(vs SCE)出现两个氧化峰, 二者电流密度分别为16 和42 mA·cm-2, 约为纯Pt电极的2倍和1.5倍, 反应过程受浓差扩散控制.     

乙二醛在Ti/纳米TiO2-Pt修饰电极上的电催化氧化

采用溶胶.凝胶和电沉积法制备Ti基纳米TiO2-Pt(Ti/纳米TiO2-Pt)修饰电极.X射线衍射(XRD)表明纳米TiO2为锐钛矿型,扫描电镜(SEM)显示Pt纳米粒子在纳米TiO2多孔膜的表面呈现簇分散状态,平均粒径约25nm.通过循环伏安(CV)和计时电流法研究了Ti/纳米TiO2-Pt修饰电极对乙二醛直接电氧化的电催化活性,结果表明,修饰电极对乙二醛的直接电氧化呈现良好的催化活性,在0.60和1.23 V(vs SCE)出现两个氧化峰,二者电流密度分别为16和42 mA·cm2,约为纯Pt电极的2倍和1.5倍,反应过程受浓差扩散控制.     

铁铂核壳纳米粒子修饰玻碳电极制备及对亚硝酸盐还原的电催化性能

通过循环伏安法（CV）在玻碳（GC）电极表面电沉积出分布较为均匀的纳米Fe粒子,制得纳米Fe粒子修饰的GC（纳米Fe/GC）电极,再经“电荷置换”制得具有Fe核Pt壳结构的纳米粒子修饰的（纳米PtFe/GC）电极。 SEM结果显示,纳米Fe/GC和纳米PtFe/GC表面粒子的形貌均呈立方体形,分布较为均匀,粒径在60 nm左右。 纳米PtFe/GC电极对亚硝酸盐的还原具有很高的电催化活性。 3种电极的电催化活性顺序依次为：纳米Fe/GC＜纳米Pt/GC＜纳米PtFe/GC。 相对于纳米Pt/GC电极,纳米PtFe/GC电极的起始还原电位（Ei）正移了0.14 V,还原峰电流（ip）增大了3倍。     

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.     

电沉积三维多孔Pt/SnO2薄膜及其对甲醇的电催化氧化

在高电流密度下以阴极析出的氢气泡为“模板”电沉积三维多孔Sn薄膜, 经在200 ℃ 2 h和400 ℃ 2 h热处理氧化后电沉积金属Pt, 制得三维多孔的Pt/SnO₂ (3D-Pt/SnO₂)薄膜. 通过扫描电镜(SEM)和X射线衍射(XRD)分析了薄膜的形貌和结构. 结果显示Pt主要沉积在SnO₂枝晶上, 形成Pt_shell/SnO_2core结构的枝晶. 在0.5 mol•dm^－3 H₂SO₄＋1.0 mol•dm^－3 CH₃OH溶液中的循环伏安结果表明, 3D-Pt/SnO₂薄膜电极在酸性溶液中电催化氧化甲醇的性能优于电沉积的纯铂电极, 而且具有较高的稳定性.     

纳米颗粒结合ZIF-67衍生的PtCo-NC催化剂用于醇类燃料电氧化

Alcohols fuel electro-oxidation is significant to the development of direct alcohols fuel cells, that are considered as a promising power source for portable electronic devices. Currently, the catalyst was restricted by the serious poisoning effect and high cost of noble metals. Developing low-cost Pt alloy with high performance and anti-CO poisoning ability was highly desired. In this work, PtCo-NC catalyst was synthesized by combining Pt nanoparticles with ZIF-67 after annealing in the tube furnace and the in situ generated N-doped carbon from ZIF-67 was functionalized to support the PtCo alloy nanoparticle. The structure and morphology were probed by X-ray diffraction, scanning electron microscope and transmission electron microscope, and the electrochemical performance was evaluated for alcohols of methanol and ethanol oxidation in the acid electrolyte. Compared with the reference sample of Pt/C, several times performance enhancement for alcohols fuel oxidation was found on PtCo-NC catalyst as well as the good catalytic stability. Specifically, the peak current density of PtCo-NC was 79.61 mA∙cm⁻² for methanol oxidation, about 2.2 times higher than that of the Pt/C electrode (36.97 mA∙cm⁻²) and 2.5 times higher than that of the commercial Pt/C electrode (31.23 mA∙cm⁻²); it was 62.69 mA∙cm^–2 for ethanol oxidation, about 1.65 times higher than that of Pt/C catalyst (37.99 mA∙cm⁻²) and commercial Pt/C electrode (37.77 mA∙cm⁻²). These catalytic performances were also much higher than some analogous catalysts developed for alcohols fuel oxidation. A much higher anti-CO poisoning ability was demonstrated by the CO stripping voltammetry experiment, in which the CO_ad oxidation peak potential for PtCo-NC was 0.46 V, ca. 110 mV negative shift compared with Pt/C catalyst at 0.57 V. A strong electronic effect was indicated by the peak position shifting to the lower binding energy direction by 0.3 eV on PtCo-NC compared with Pt/C reference catalyst. According to the d-band center theory, the electron-enriched state of Pt will decrease the interaction strength of poisoning intermediates adsorbed on its surface; Moreover, according to the bifunctional catalytic mechanism, the presence of Co can form the adsorbed oxygen-containing species (―OH) more easily than Pt at low potentials, and this oxygen-species were helpful in the oxidation of CO_ad at neighboring Pt sites. The high catalytic performance for alcohols fuel oxidation could be due to the largely improved anti-CO poisoning ability and the synergistic effect between the in situ formed PtCo nanoparticles and the N-doped carbon support.     

新型气体扩散电极体系高效产H2O2的研究

以自制新型石墨/聚四氟乙烯(PTFE)气体扩散电极在无隔膜体系中进行双氧水发生工艺的优化研究, 主要探讨了不同石墨和PTFE质量比、阴极电位、pH值和氧气流速对H2O2产率的影响. 结果表明, 以石墨和PTFE质量比为2:1的气体扩散电极为阴极, 在pH=3, Na2SO4浓度为0.1 mol•L−1, 氧气流速为0.4 L•min−1, 阴极电位为−0.55 V (vs SCE)时, 2 h后H2O2可以达到60 mg•L−1. 该新型体系有较高的H2O2产率和电流效率(可达60%以上), 且pH值适用范围较广, 可望应用于水中污染物的处理.     

Nickel foam-based composite electrodes for electrooxidation of methanol

Nickel foam and five nickel foam-based composite electrodes were prepared for being used as anode materials for the electrooxidation of methanol in KOH solution containing 0.1 and 1.0 M of methanol. The layered electrodes composed of nickel foam, platinum nanoparticles, polyaniline (PANI) and/or porous carbon (C) prepared in various assemblies. As shown by SEM analysis, depending on the preparation conditions, the electrodes of different morphologies were obtained. Using the cyclic voltammetry method, the oxidation of methanol on nickel foam electrode was observed in the potential range 0.4 V ↔ 0.7 V, where the Ni(OH)₂/NiOOH transformation occurred. The presence of Pt particles in electrode gave rise to the increase in electrocatalytic activity in this potential range. For electrodes containing dispersed platinum catalyst (Ni/Pt, Ni/PANI/Pt and Ni/C/Pt), the oxidation of methanol was noted also in the potential range −0.5 V ↔ 0.1 V. The electrocatalytic activities of the examined electrodes toward methanol oxidation at low potentials were in order Ni/Pt > Ni/C/Pt > Ni/PANI/Pt, whereas at high potentials in order Ni/PANI/Pt > Ni/Pt> Ni/C/Pt > Ni. Among the examined electrodes, the most resistant to cyclic poisoning appeared to be the Ni/C/Pt electrode. Presented at the 4Th Baltic Conference on Electrochemistry, Greifswald, March 13–16, 2005     

三组Pt- Ru/C催化剂前驱体对其性能的影响

分别以三组不同的Pt和Ru化合物为前驱体, 采用热还原法制备了Pt-Ru/C催化剂, 比较不同前驱体对催化剂性能的影响；通过XRD和TEM技术对催化剂的晶体结构及微观形貌进行了分析. 结果表明以H₂PtCl₆+RuCl₃和自制(NH₄)₂PtCl₆+Ru(OH)₃为前驱体的催化剂Pt和Ru没有完全形成合金状态, 在Pt(111)和Pt(200)之间有Ru(101)存在；以Pt(NH₃)₂(NO₂)₂和自制含钌化合物为前驱体制备的催化剂未检测出Ru金属或其氧化物的衍射峰, Pt-Ru颗粒在载体上分散均匀, 粒径最小, 为3.7 nm. 利用玻碳电极测试了循环伏安、记时电流和阶跃电位曲线, 考核了上述催化剂对甲醇阳极催化氧化活性的影响；结果表明：以Pt(NH₃)₂(NO₂)₂和自制含钌化合物为前驱体制备的催化剂对甲醇的电催化氧化活性最高, 循环伏安曲线峰电流密度达11.5 mA•cm^-2.     

CoPt nanoparticles and their catalytic properties in electrooxidation of CO and CH(3)OH studied by in situ FTIRS

CoPt nanoparticles supported on a glassy carbon electrode (denoted as CoPt/GC) were prepared by galvanic replacement reaction between electrodeposited Co nanoparticles and K(2)PtCl(6) solution. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were both employed to characterize the CoPt nanoparticles. It was shown that the CoPt nanoparticles have irregular shapes and most of them exhibit a core-shell structure with a porous Co core and a shell of Pt tiny particles. The composition of the CoPt nanoparticles was analyzed by energy-dispersive X-ray spectroscopy (EDX), which depicts a Co : Pt ratio of ca. 21 : 79. Studies of cyclic voltammetry (CV) demonstrated that CoPt/GC possesses a much higher catalytic activity towards CO and methanol electrooxidation than a nanoscale Pt thin film electrode. In situ FTIR spectroscopic studies have revealed for the first time, that a CoPt nanoparticles electrode exhibits abnormal IR effects (AIREs) for IR absorption of CO adsorbed on it. In comparison with the IR features of CO adsorbed on a bulk Pt electrode, the direction of the IR bands of CO adsorbed on the CoPt/GC electrode is inverted completely, and the intensity of the IR bands has been enhanced up to 15.4 times. The AIREs is significant in detecting the adsorbed intermediate species involved in electrocatalytic reactions. The results demonstrated a reaction mechanism of CH(3)OH oxidation on CoPt/GC in alkaline solutions through evidencing CO(L), CO(M), HCOO(-), CO(3)(2-), HCO(3)(-) and CO(2) as intermediate and product species by in situ FTIRS.     

羧甲基化壳聚糖- Fe3O4纳米粒子的制备及对Zn2+的吸附行为

以共沉淀法制备纳米Fe3O4, 通过在颗粒表面接枝羧甲基化壳聚糖(CMC), 制备一种新型磁性纳米吸附剂, 用透射电镜(TEM)、X射线衍射分析(XRD)等对其进行了表征, 并考察了吸附剂对Zn2+的吸附性能. 结果表明, 制备的磁性纳米吸附剂平均粒径18 nm, 粒子中CMC的含量约5%. 该吸附剂对Zn2+吸附速率很快, 在2 min内基本达到平衡, 能有效去除Zn2+. 等温吸附数据符合Langmuir模型, 饱和吸附容量为20.4 mg•g−1, 吸附常数为0.0314 L•mg−1. 热力学计算表明吸附为放热过程, 焓变为−5.68 kJ•mol−1.