Pd/MWCNTs(多壁碳纳米管)催化剂的制备及其Heck反应催化活性

以浓硝酸处理后的多壁碳纳米管(MWCNTs)为载体,通过微波辅助法简单而快速地制备了高度分散、粒径均一的Pd/MWCNTs催化剂。利用XRD、HRTEM、XPS等手段对催化剂进行了表征。考察了Pd/MWCNTs催化剂对Heck反应的催化活性,并优化了反应温度、碱的种类和用量等反应条件。结果表明,Pd/MWCNTs在Heck反应中具有良好的催化活性。     

非质子介质中氧电还原的研究：Ⅲ.金属卟啉电催化氧还原及反应的研究

金属卟啉化合物在生物领域中的作用引起了人们的广泛注意.尤其是其催化作用以及电子转移方面已有很多报道.在催化方面大多数是利用氧化剂把中心离子氧化成高价态,而利用卟啉低价态进行催化方面的研究报道还很少。在这一方面我们已经做了一些工作,氧电还原产生的超氧离子[O_2~÷]虽能参与许多有机反应,如亲核取代,环氧化,氧     

交替微波加热法对制备氧还原催化剂性能的影响

详细研究了交替微波加热法制备多壁碳纳米管负载Pt催化剂(Pt/MWCNTs)的过程中交替微波加热(5s-on/5s-off)次数对催化剂性能的影响.X射线粉末衍射(XRD)结果表明,Pt的晶粒尺寸在开始的加热阶段基本上没有发生变化,但是随着加热次数的增多,Pt的晶粒尺寸逐步增大.采用循环伏安法和旋转圆盘电极技术考察了催化剂的电化学活性.结果显示,以5s-on/5s-off加热20次时,催化剂显示出最佳的催化活性;在0.5mol· L-1 H2SO4饱和氧水溶液中催化剂的氧还原起峰电位接近1.0 V(vs RHE).交替微波加热法简单经济,在大批量制备催化剂等纳米材料方面显示出较好的应用前景.     

金属卟啉有机共价和非共价修饰多壁碳纳米管

合成了5-(4-羟基苯基)-10,15,20-三苯基卟啉锌配合物, 与活化的多壁碳纳米管(MWNT)发生酯化反应, 从而得到金属卟啉有机共价化学修饰的多壁碳纳米管复合物; 利用金属卟啉环上的π电子与多壁碳纳米管管壁上的π电子通过π-π堆积效应, 得到金属卟啉有机非共价修饰的多壁碳纳米管复合物. 通过透射电镜(TEM)考察了金属卟啉-多壁碳纳米管复合物的形貌特征; 通过红外光谱对产物的化学结构进行了表征; 通过紫外光谱、荧光光谱和热失重分析(TGA)对比分析了两类复合物, 发现非共价修饰的金属卟啉-碳纳米管复合物的荧光淬灭率更高, 非共价修饰的金属卟啉-碳纳米管复合物中卟啉的含量比较高.     

金属卟啉化学共价和非共价修饰多壁碳纳米管

合成了5-(4-羟基苯基)-10,15,20-三苯基卟啉锌配合物,与活化的多壁碳纳米管(MWNT)发生酯化反应,从而得到金属卟啉有机共价化学修饰的多壁碳纳米管复合物;利用金属卟啉环上的π电子与多壁碳纳米管管壁上的π电子通过π-π堆积效应,得到金属卟啉有机非共价修饰的多壁碳纳米管复合物.通过透射电镜(TEM)考察了金属卟啉-多壁碳纳米管复合物的形貌特征;通过红外光谱对产物的化学结构进行了表征;通过紫外光谱、荧光光谱和热失重分析(TGA)对比分析了两类复合物,发现非共价修饰的金属卟啉-碳纳米管复合物的荧光淬灭率更高,非共价修饰的金属卟啉-碳纳米管复合物中卟啉的含量比较高.     

乙二胺接枝改性碳纳米管负载的乙醇氧化电催化剂Pt及Pt-Ru的制备及电催化性质

采用化学法制备了乙二胺接枝改性碳纳米管（ED/MWNTs）负载的Pt及Pt-Ru催化剂,并用红外光谱法、透射电镜分析（TEM）及X射线能谱技术对催化剂进行了表征。结果表明：乙二胺对碳纳米管的改性使Pt及Pt-Ru在碳管上的分布更均匀,粒径更小。同时,催化剂对乙醇电催化氧化活性的电化学研究结果表明：乙二胺改性可明显提高Pt-Ru/MWNTs/C 和Pt/MWNTs/C的电催化活性,而且Pt/ED/MWNTs/C的活性甚至比Pt-Ru/MWNTs/C的活性还高。由此,ED/MWNTs作为乙醇电氧化催化剂的载体有着很好的应用前景。     

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.     

氮掺杂碳纳米管高负载金属催化剂在铝空气电池中的应用

在铁基催化剂(Fe-N-C)中引入金属铈,采用高温热解法合成了氮掺杂碳纳米管(NCNTs)高负载金属催化剂(Fe/Ce-NCNTs)。金属铈的引入能更好地促进碳纳米管(CNTs)的生长,锚定更多的铁原子,增加Fe—NX活性位点的数量。Fe/CeNCNTs催化剂在碱性介质中表现出良好的催化活性和稳定性,半波电位为0.86 V(vs RHE)。将Fe/Ce-NCNTs催化剂应用于铝空气电池(AABs),其峰值功率密度可达142 mW·cm^-2,在50 mA·cm^-2电流密度下放电比容量达到865 mAh·g^-1,在高电流密度负载下具有较高的电压。     

Preparation and Catalytic Activity of Carbon Nanotube-Supported Metalloporphyrin Electrocatalyst

The multiwalled carbon nanotube-supported CoTMPP (CoTMPP/MWNT) electrocatalyst was prepared by the microwave synthesis method, and its microstructure was characterized using transmission electron microscopy. The electrocatalytic performance of CoTMPP/MWNT for oxygen reduction reaction (ORR) was evaluated by rotating disc electrode and rotating ring disc electrode technique. Compared with the CoTMPP/MWNT electrocatalyst prepared by the traditional organic reflux method, the one prepared by the microwave synthesis method showed better performance for ORR, and the half-wave potential exhibited a positive shift of 110 mV. Compared with CoTMPP/BP2000, the CoTMPP/MWNT electrocatalyst showed a 10 mV higher on-set potential and a 21% lower reduction current loss in ORR, indicating that the CoTMPP/MWNT electrocatalyst had higher catalytic activity and better stability than CoTMPP/BP2000. The number of exchanged electrons during ORR and the yield of peroxide were 3.6 and 18%, respectively. The high corrosion resistance and unique electronic property of MWNT, and the interaction between MWNT and active metal ions can efficiently improve the electrocatalytic performance of the CoTMPP/MWNT catalyst.     

The Proportion of Fe‐NX,N Doping Species and Fe3C to Oxygen Catalytic Activity in Core‐Shell Fe‐N/C Electrocatalyst

A bifunctional oxygen electrocatalyst composed of iron carbide (Fe₃C) nanoparticles encapsulated by nitrogen doped carbon sheets is reported. X‐ray photoelectron spectroscopy and X‐ray absorption near edge structure revealed the presence of several kinds of active sites (Fe?N_x sites, N doping sites) and the modulated electron structure of nitrogen doped carbon sheets. Fe₃C@N‐CSs shows excellent oxygen evolution and oxygen reduction catalytic activity owing to the modulated electron structure by encapsulated Fe₃C core via biphasic interfaces electron interaction, which can lower the free energy of intermediate, strengthen the bonding strength and enhance conductivity. Meanwhile, the contribution of the Fe?N_x sites, N doping sites and the effect of Fe₃C core for the electrocatalytic oxygen reaction is originally revealed. The Fe₃C@N‐CSs air electrode‐based zinc‐air battery demonstrates a high open circuit potential of 1.47 V, superior charge‐discharge performance and long lifetime, which outperforms the noble metal‐based zinc‐air battery.     

负载硫化钴纳米颗粒的N、S共掺杂石墨烯氧还原电催化剂的制备及性能

采用D-氨基葡萄糖作为Co分散剂和碳源,硫脲作为氮源和硫源,以NaCl为模板制备负载硫化钴纳米颗粒的N、S共掺杂三维石墨烯氧还原电催化剂(CoS/N/S/rGO)。CoS/N/S/rGO具有良好的氧还原反应(ORR)活性,起始电位和半波电位分别为960和815 mV,性能与商业Pt/C相当。此外,CoS/N/S/rGO表现出明显的4电子转移特性和超低的过氧化氢产率。与基于Pt/C的锌-空气电池相比,基于CoS/N/S/rGO的锌-空气电池在6 mol·L~(-1) KOH和0.2 mol~(-1) Zn(CH_3COO)_2碱性电解质中显示出更高的恒电流放电性能以及更好的稳定性。     

Carbon Nanotube Supported Molybdenum Carbide as Robust Electrocatalyst for Efficient Hydrogen Evolution Reaction

Molybdenum carbide is considered to be one of the most competitive catalysts for hydrogen evolution reaction (HER) regarding its high catalytic activity and superior corrosion resistance. But the low electrical conductivity and poor interfacial contact with the current collector greatly inhibit its practical application capability. Herein, carbon nanotube (CNT) supported molybdenum carbide was assembled via electrostatic adsorption combined with complex bonding. The N-doped molybdenum carbide nanocrystals were uniformly anchored on the surfaces of amino CNTs, which depressed the agglomeration of nanoparticles while strengthening the migration of electrons. The optimized catalyst (250-800-2h) showed exceptional electrocatalytic performance towards HER under both acidic and alkaline conditions. Especially in 0.5 M H₂SO₄ solution, the 250-800-2h catalyst exhibited a low overpotential of 136 mV at a current density of 10 mA/cm² (η₁₀) with the Tafel slope of 49.9 mV dec⁻¹, and the overpotential only increased 8 mV after 20,000 cycles of stability test. The active corrosive experiment revealed that more exposure to high-activity γ-Mo₂N promoted the specific mass activity of Mo, thus, maintaining the catalytic durability of the catalyst.     

乙醇在碳修饰的二氧化钛纳米管负载的钯电催化剂上的催化氧化

 通过有机物分解碳化处理TiO2 纳米管制得了TiO2C, 并以其为载体制备了Pd/TiO2C电催化剂,考察了该催化剂对碱性介质中乙醇电催化氧化的活性. 结果表明,碳化导电处理的TiO2C纳米管载体能有效改善催化剂中贵金属的分散度和电极结构,从而提高催化剂的电催化活性. 对催化剂活性组分的优化实验表明, Pd/TiO2C质量比为1/1时催化剂的活性最高. 在1 mol/L KOH溶液中Pd载量均为0.3 mg/cm2的条件下, Pd/TiO2C催化剂对乙醇氧化的催化活性是Pd/C催化剂的3.8倍.     

Preparation and Catalytic Performance of Carbon Nanotube Supported Palladium Catalyst

Two carbon nanotube supported palladium catalysts were prepared using a chemical reduction technique (Pd/CR‐CNT) and a conventional impregnation method (Pd/CNT) respectively, and their catalytic performances for Heck reaction were investigated. The catalysts were characterized by TEM and XPS techniques and the products were characterized by ¹H NMR. Research results showed that the (Pd/CR‐CNT) catalyst showed a better catalytic activity than the (Pd/CNT) catalyst, owing to better dispersion of palladium nanoparticles and stronger interaction between the active palladium species and carbon nanotube. Meanwhile, the product yield maintained 99.93% of its initial value at five‐times re‐use, compared with that at the first time use. The catalyst prepared with the chemical reduction method represented a better reusing performance.     

氮化钨-钨/掺氮有序介孔碳复合材料的制备及其氧还原性能

采用软模板法制备了氮化钨-钨/掺氮有序介孔碳复合材料（WN-W/NOMC）,作为一种高比表面积且价格低廉的阴极氧还原反应催化剂。通过适量添加尿素来改变复合材料中的氮含量,在掺氮量为7%（w/w）时,实验发现材料能够保持完整有序介孔结构,测试其比表面积高达835 m²·g^-1,透射电子显微镜（TEM）测试结果显示其催化颗粒均匀地分散在氮掺杂有序介孔碳载体上。在O₂饱和的0.1 mol·L^-1 KOH溶液中测试了材料的氧还原催化性能（ORR）,显示其起始电位为0.87 V（vs RHE）,极限电流密度为4.49 mA·cm^-2,氧还原反应的转移电子数为3.4,接近于20%（w/w）商业Pt/C的3.8,说明该材料表现出近似4电子的氧还原反应途径。研究结果表明,WN-W/NOMC的催化性能虽然稍弱于商业铂碳（0.99 V,5.1 mA·cm^-2）,但其具有远超铂碳的循环稳定性和耐甲醇毒化能力。     

氮化钨-钨/掺氮有序介孔碳复合材料的制备及其氧还原性能

采用软模板法制备了氮化钨-钨/掺氮有序介孔碳复合材料(WN-W/NOMC),作为一种高比表面积且价格低廉的阴极氧还原反应催化剂。通过适量添加尿素来改变复合材料中的氮含量,在掺氮量为7%(w/w)时,实验发现材料能够保持完整有序介孔结构,测试其比表面积高达835 m~2·g~(-1),透射电子显微镜(TEM)测试结果显示其催化颗粒均匀地分散在氮掺杂有序介孔碳载体上。在O_2饱和的0.1 mol·L~(-1 )KOH溶液中测试了材料的氧还原催化性能(ORR),显示其起始电位为0.87 V(vs RHE),极限电流密度为4.49 mA·cm~(-2),氧还原反应的转移电子数为3.4,接近于20%(w/w)商业Pt/C的3.8,说明该材料表现出近似4电子的氧还原反应途径。研究结果表明,WN-W/NOMC的催化性能虽然稍弱于商业铂碳(0.99 V,5.1 mA·cm~(-2)),但其具有远超铂碳的循环稳定性和耐甲醇毒化能力。     

Dual‐Template Pore Engineering of Whey Powder‐Derived Carbon as an Efficient Oxygen Reduction Reaction Electrocatalyst for Primary Zinc‐Air Battery

Cost‐effective and high‐performance electrocatalysts for oxygen reduction reactions (ORR) are needed for many energy storage and conversion devices. Here, we demonstrate that whey powder, a major by‐product in the dairy industry, can be used as a sustainable precursor to produce heteroatom doped carbon electrocatalysts for ORR. Rich N and S compounds in whey powders can generate abundant catalytic active sites. However, these sites are not easily accessible by reactants of ORR. A dual‐template method was used to create a hierarchically and interconnected porous structure with micropores created by ZnCl₂ and large mesopores generated by fumed SiO₂ particles. At the optimum mass ratio of whey power: ZnCl₂ : SiO₂ at 1 : 3 : 0.8, the resulting carbon material has a large specific surface area close to 2000 m² g^?1, containing 4.6 at.% of N with 39.7% as pyridinic N. This carbon material shows superior electrocatalytic activity for ORR, with an electron transfer number of 3.88 and a large kinetic limiting current density of 45.40 mA cm^?2. They were employed as ORR catalysts to assemble primary zinc‐air batteries, which deliver a power density of 84.1 mW cm^?2 and a specific capacity of 779.5 mAh g^?1, outperforming batteries constructed using a commercial Pt/C catalyst. Our findings open new opportunities to use an abundant biomaterial, whey powder, to create high‐value‐added carbon electrocatalysts for emerging energy applications.     

A Novel Carbon Nanotube-Supported NiP Amorphous Alloy Catalyst and Its Hydrogenation Activity

A carbon nanotube-supported NiP amorphous catalyst (NiP/CNT) was prepared by induced reduction. Benzene hydrogenation was used as a probe reaction for the study of catalytic activity. The effects of the support on the activity and thermal stability of the supported catalyst were discussed based on various characterizations, including XRD, TEM, ICP, XPS, H2-TPD, and DTA. In comparison with the NiP amorphous alloy, the benzene conversion on NiP/CNT catalyst was lower, but the specific activity of NiP/CNT was higher, which is attributed to the dispersion produced by the support, an electron-donating effect, and the hydrogen-storage ability of CNT. The NiP/CNT thermal stability was improved because of the dispersion and electronic effects and the good heat-conduction ability of the CNT support.