扫帚状氧化铈制备及其对Pt基阳极催化剂催化性能的影响

采用水热合成法,合成了比表面积为175 m²·g^-1,孔径在2~4nm范围内的扫帚状CeO₂。通过微波辅助乙二醇还原氯铂酸法制备了Pt-CeO₂/RGO催化剂,探究扫帚状CeO₂的添加对Pt基催化剂电催化性能的影响。利用X射线衍射仪（XRD）、扫描电镜（SEM）、N₂吸附-脱附、X射线光电子能谱（XPS）对所制备的CeO₂及催化剂进行表征。利用电化学工作站对催化剂进行电化学性能测试。结果表明,催化剂中CeO₂保持原有扫帚状,Pt纳米粒子均匀分布于石墨烯载体表面;当m_RGO∶m_CeO2=1∶2时,添加了扫帚状CeO₂的Pt-CeO₂/RGO催化剂的电催化性能最优,电化学活性表面积为102.83 m²·g^-1,对乙醇氧化的峰值电流密度为757.17 A·g^-1,1 000 s的稳态电流密度为108.17 A·g^-1,对乙醇催化氧化反应的电荷转移电阻最小,活化能最低。     

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。     

碳纳米管上原位沉积钯-钴-镍纳米颗粒及其对乙醇氧化的电活性

以水合肼为还原剂,在水和乙醇的混合溶液中制备多壁碳纳米管(MWCNT)负载的纳米镍(Ni/MWCNT)和纳米镍钴(Ni-Co/MWCNT)颗粒,然后将它们分别与氯化钯溶液反应,形成的钯纳米颗粒原位沉积在MWCNT表面,从而得到MWCNT负载的Pd-Ni/MWCNT和Pd-Ni-Co/MWCNT催化剂。SEM和TEM图像显示,MWCNT上的催化剂颗粒是由5~10 nm的小颗粒团聚而成的30~100 nm的大颗粒,三金属催化剂的粒径比双金属的粒径小,在MWCNT上的分散度更高。ICP和EDS分析显示,Pd直接还原并包覆在纳米镍和纳米镍钴表面;采用循环伏安和计时电流技术,研究了催化剂在碱性溶液中对乙醇氧化的电催化活性,结果表明,Pd-Ni-Co/MWCNT催化剂对乙醇氧化具有强的电催化活性,乙醇氧化对应的峰电流密度达101.8 mA·cm^-2,并且催化剂催化活性稳定。     

Effect of Experimental Variables on the Combustion Characteristics of Water-in-Diesel Emulsion Fuels

Water-in-diesel (W/D) emulsion fuels were prepared through an ultrasonic processor by using high energy emulsification method. Accordingly, the physical and chemical properties were analyzed. A decrease in viscosity was found in the emulsion fuel in contrast to the neat diesel which signifies the enhanced fluidity of the fuel. The emulsion fuel was then used to carry combustion tests in an internal combustion engine. A decrease in exhaust temperature was observed when a high surfactant to water ratio was used, which lead to minimal heat loss. As water is emulsified with diesel, effectiveness of combustion is improved rather than neat diesel fuel. It was also explored that the addition of water-in-diesel is influential in terms of reduction in exhaust gas emission such as carbon dioxide, carbon monoxide, ammonia from the internal combustion engine. Therefore, this type of emulsion fuel would be a useful contribution in the fuel economy, but also in making it environmentally friendly since diesel fuel is now considered one of the leading fuels causing ecological contamination.     

Effects of Magnetic Nanofluid Fuel Combustion on the Performance and Emission Characteristics

Although the compression ignition engines are a significant source of power, their detrimental emissions create considerable problems to the environment as well as to humans. The objective of the present experimental investigation is to examine the effects of the magnetic nanofluid fuels on combustion performance characteristics and exhaust emissions. In this regard, the Fe₃O₄ nanoparticles dispersed in the diesel fuel with the nanoparticle concentrations of 0.4 and 0.8 vol% were employed for combustion in a single-cylinder, direct-injection diesel engine. After a series of experiments, it was demonstrated that the nanoparticle additives, even at very low concentrations, have considerable influence in diesel engine characteristics. Furthermore, the results indicated that the nanofluid fuel with nanoparticle concentration of 0.4 vol% shows better combustion characteristics in comparison with that of 0.8 vol%. Based on the experimental results, NO _x and SO₂ emissions dramatically reduce, while CO emissions and smoke opacity noticeably increase with increasing the dosing level of nanoparticles.     

Tween-80–n-Butanol–Diesel–Water Microemulsion System—A Class of Alternative Diesel Fuel

Tween-80–n–butanol–diesel–water microemulsion systems with various surfactant:cosurfactant (S:C) ratio have been reported as a class of alternative diesel fuel from their phase behavior, clouding phenomena, conductivity, turbidity, and inflammation studies. Temperature induced clouding of microemulsion containing 2% brine at an S:C ratio of 1:1 from a suitable turbid zone has been examined to see the stability of the diesel–water microemulsion systems. Regression models have been proposed to understand the impact of various components of the microemulsion on their cloud point (CP) values. Conductivity of the microemulsions at various S:C ratio increases with the volume of brine having two cut points depicting the presence of three microheterogenous phases within the system, whereas turbidity shows a linear increase. Dye-probed investigation of water-rich and oil-rich zones of the microemulsions indicates the involvement of a dynamic mass transfer process within the various zones. The intensities of flames produced during burning of the microemulsions with various O:E:W weight percentages selected from the isotropic regions of the phase diagrams have been estimated using MATLAB image processing method and the impacts of various components on the fuel use of the microemulsions have been analyzed.     

生物燃料电池处理生活污水同步产电特性研究

以某生活污水处理厂缺氧池活性污泥为接种体,以葡萄糖为模拟生活废水,构建双室型微生物燃料电池。利用微生物燃料电池(MFC,Microbial fuel cell)实现生活废水降解与同步产电。研究基质降解动力学及温度对MFC电极过程动力学的影响,明确微生物电化学活性、阳极传荷阻抗、阳极电势、电池产能之间的关系,考察库伦效率及COD去除率。研究结果表明,电池功率输出与基质浓度关系遵循莫顿动力学方程:P=Pmaxc/(ks+c),其中,半饱和常数ks为138.5 mg/L,最大功率密度Pmax为320.2 mW/m2。葡萄糖浓度较小时,反应遵循一级动力学规律:-dcA/dt=kcA,k=0.262 h-1。操作温度从20℃提高到35℃,生物膜电化学活性不断提高,传荷阻抗从361.2Ω减小到36.2Ω,阳极电极电势不断降低,同时,峰值功率密度从80.6 mW/m2提高到183.3 mW/m2。45℃时,产电菌活性降低,峰值功率密度减小到36.8 mW/m2。葡萄糖浓度为1 500 mg/L,温度为35℃时,MFC电化学性能最佳,稳定运行6 h后库伦效率为44.6%,COD去除率为49.2%。     

碳纤维基PtPb阳极催化剂的制备及其电催化性能

以静电纺丝技术与烧结工艺相结合的方式制备了碳纤维基PtPb纳米催化剂,并采用X射线衍射（XRD）、红外光谱（FT-IR）、扫描电镜（SEM）等分析测试手段对其进行了表征。结果表明,在预氧化温度为300 ℃、碳化温度为800 ℃的条件下,所制备的PtPb阳极纳米催化剂结晶程度好、比表面积大,粒径约为3.05 nm,催化活性颗粒均匀分散在多孔碳纤维骨架上。采用循环伏安法（CV）及交流阻抗（EIS）评价了该催化剂对乙醇氧化反应的电催化性能。结果表明,最大峰电流密度达到125 mA/cm²,电荷转移电阻相较于700 ℃下降了近60%。     

Synthesis of dual-doped non-precious metal electrocatalysts and their electrocatalytic activity for oxygen reduction reaction

The pyrolyzed carbon supported ferrum polypyrrole(Fe-N/C) catalysts are synthesized with or without selected dopants, p-toluenesulfonic acid(TsOH), by a facile thermal annealing approach at desired temperature for optimizing their activity for the oxygen reduction reaction(ORR) in O2-saturated 0.1 mol/L KOH solution. The electrochemical techniques such as cyclic voltammetry(CV) and rotating disk electrode(RDE) are employed with the Koutecky-Levich theory to quantitatively obtain the ORR kinetic constants and the reaction mechanisms. It is found that catalysts doped with TsOH show significantly improved ORR activity relative to the TsOH-free one. The average electron transfer numbers for the catalyzed ORR are determined to be 3.899 and 3.098, respectively, for the catalysts with and without TsOH-doping. The heat-treatment is found to be a necessary step for catalyst activity improvement, and the catalyst pyrolyzed at 600℃ gives the best ORR activity. An onset potential and the potential at the current density of-1.5 mA/cm2 for TsOH-doped catalyst after pyrolysis are 30 mV and 170 mV, which are more positive than those without pyrolized. Furthermore, the catalyst doped with TsOH shows higher tolerance to methanol compared with commercial Pt/C catalyst in 0.1 mol/L KOH. To understand this TsOH doping and pyrolyzed effect, X-ray diffraction(XRD), scanning electron microscope(SEM) and X-ray photoelectron spectroscopy(XPS) are used to characterize these catalysts in terms of their structure and composition. XPS results indicate that the pyrrolic-N groups are the most active sites, a finding that is supported by the correspondence between changes in pyridinic-N content and ORR activity that occur with changing temperature. Sulfur species are also structurally bound to carbon in the forms of C–Sn–C, an additional beneficial factor for the ORR.