石墨烯/Sr2Ni0.4Co1.6O6复合材料的制备及其性能

通过溶胶-凝胶法合成了双钙钛矿型氧化物Sr_2Ni_(0.4)Co_(1.6)O_6、通过改性Hummers还原方法制备出薄层石墨烯,并制备单一物质和两者复合材料的双功能氧电极,用于测试其氧催化性能。采用XRD、EDS、SEM、FTIR对样品进行表征。结果显示:Sr_2Ni_(0.4)Co_(1.6)O_6均匀地分布于薄层石墨烯片层表面。电化学性能测试结果表明:单一Sr_2Ni_(0.4)Co_(1.6)O_6和薄层石墨烯的氧还原反应(ORR)最大电流密度分别为0.1830、0.1516A/cm~2 (–0.6Vvs.Hg/Hg O),氧析出反应(OER)最大电流密度分别为0.2677、0.1174 A/cm~2 (1 V vs. Hg/HgO)。当薄层石墨烯添加量占复合催化剂质量的10%时,复合催化剂的氧催化性能最佳,ORR最大电流密度为0.2901 A/cm~2(–0.6Vvs.Hg/Hg O),OER最大电流密度为0.3905 A/cm~2 (1 V vs. Hg/HgO),明显高于单一催化剂。     

二氧化锰的碳酸锰热解制备及其对氧还原催化性能研究

用碳酸锰热解的方法制得化学二氧化锰,用X射线衍射确定其纯度为100%。以制得的二氧化锰为催化剂,以炭黑(Vulcan XC-72)为载体,制备成气体扩散电极,显示出对氧还原的优越催化性能。碱性条件下,电极在-0.2 V(vs Hg/HgO)电位下,电流密度达到94 mA/cm2(不加催化剂时为9 mA/cm2)。     

新型碳载MnO2空气电极的研究

为了使空气电极在近低极化区获得较好的催化效果,本文以碳载MnO_2为催化剂制备了空气电极,通过测定稳态阴极极化曲线,研究了催化剂及电极制备工艺对氧空气电极的电化学性能的影响。实验发现碳载MnO_2催化剂可有效降低空气电极在近低极化区工作时的极化程度,空气电极工作电流密度可达43mA·cm~(-2)(电位-0．2V v．s．Hg/HgO参比电极),交换电流密度为0．0593mA·cm~(-2);空气电极最佳制备工艺条件为：10%无水Na_2SO_4(造孔剂) 15%PTFE(粘合剂) 镀银镍网(集流体) 15g·L~(-1)Co(Ⅱ)Schiff碱配合物(富氧材料)。     

锌-空气电池Co-PPy-C复合催化剂的电化学性能研究

采用化学氧化聚合法合成了以碳为载体的钴-聚吡咯(PPy)配合物Co-PPy-C,作为气体扩散电极的氧还原催化剂。利用极化曲线、交流阻抗、计时电流等电化学方法测试了其在碱性介质中(6 mol/L KOH)氧气气氛条件下氧还原的催化性能。电极电位在-0.20 V vs.Hg/HgO时,催化剂电流密度达到158 mA/cm2,显示出优越的氧还原电催化性能;采取催化层/集流体/气体扩散层的排布方式,以纯锌为负极,6 mol/L的KOH为电解液,将气体扩散电极与锌负极组装成锌-空气电池。电池以80 mA/cm2进行恒流放电,放电电压为1.0 V,且性能稳定。     

La2-xSrxCuO4+δ型类钙钛矿复合氧化物氧电极的电化学研究

本文合成了La2-xSrxCuO4 δ(0≤x≤1)系列类钙钛矿复合氧化物,并作为催化层电极材料制备了空气电极,在碱性介质中以Hg/HgO为参比电极通过测量电极的极化曲线、循环伏安曲线,考察了电极材料的电催化活性。研究发现,La2-xSrxCuO4 δ型类钙钛矿复合氧化物电极材料催化活性较高,并随Sr掺杂量的不同活性也有所变化,并研究了空气电极的动力学特征。     

复合氧化物La0.8Sr0.2CoO3的合成及其析氧电催化

通过有机酸辅助法在较低温度下合成了La0.8Sr0.2CoO3复合氧化物,XRD结果表明,用该方法合成的La0.8Sr0.2CoO3具有单相钙钛矿结构,从稳态物化曲线得出,在碱性溶液中,在La0.8Sr0.2CoO3表面的析氧Tafel斜率为65mV/dec,OH-的反应级数为1,在分析了反应机理后,得出了析氧反应的动力学方程,恒电流测试结果表明,用该方法制备的La0.8Sr0.2CoO3/Ni电极,在碱性溶液中具有良好的析氧催化活性.     

溶胶-凝胶燃烧法制备La_(0.6)Sr_(0.4)Co_(1-x)Mn_xO_3催化剂及其应用于苯的催化氧化

以丙烯酰胺辅助柠檬酸为络合试剂,采用溶胶-凝胶燃烧法制备La0.6Sr0.4Co1-xMnxO3催化剂(x=0.3、0.5、0.7)并与La Co O3进行比较,进行XRD、BET、SEM、XPS和苯的催化氧化性能和稳定性表征。结果表明,催化活性顺序为:La0.6Sr0.4Co0.7Mn0.3O3La0.6Sr0.4Co0.5Mn0.5O3La0.6Sr0.4Co0.3Mn0.7O3La Co O3。La0.6Sr0.4Co1-xMnxO3催化剂生成钙钛矿相的同时还伴生少量Sr CO3杂相。与La Co O3对比,La0.6Sr0.4Co1-xMnxO3催化剂拥有更大的比表面积、孔容和抗团聚性,具有更好的催化氧化活性。在La0.6Sr0.4Co1-xMnxO3(x=0.3、0.5、0.7)催化剂中,La0.6Sr0.4Co0.7Mn0.3O3催化剂比其他两种催化剂具有更高的钙钛矿相结晶度和更多的表面吸附氧与晶格氧,活性最高。78 h稳定性测试结果表明,La0.6Sr0.4Co0.7Mn0.3O3催化剂表现出良好的稳定性。     

碳载锰氧化物催化剂的掺杂改性

为提高MnO2催化剂对氧气还原的催化活性,将硝酸锰、硝酸钴、硝酸镧溶液浸渍到碳材料中,于340℃下焙烧2 h,得到空气电极催化剂,通过冷压法制作气体扩散电极。采用阴极极化曲线、稳态恒电流法和交流阻抗等方法测试了各个空气电极的电化学性能。结果表明,当催化剂中金属元素Mn、La、Co的摩尔比为1∶0.4∶0.6时,空气电极的催化活性最佳,在100,200 mA/cm2两种电流密度下,电极的工作电压平台都比MnO2电极要高,掺杂氧化镧和氧化钴还可以提高氧还原反应中催化剂在大电流密度下的稳定性。氧化镧和氧化钴的加入,减小了电化学反应动力学阻抗和氧的扩散阻抗。组装铝空气电池并进行放电测试发现,放电平台比较稳定,氧化镧和氧化钴的掺杂能显著地提高电池的放电电压。     

H2S固体氧化物燃料电池的制备及其性能

采用尿素燃烧法制备La0.6Sr0.4Co0.2Fe0.8O3-δ(记作LSCF,下同)钙钛矿型阴极催化剂前体粉末,经800℃锻烧后具有典型的钙钛矿结构。在400～950℃温度范围内,催化剂具有较高的电导率,满足固体氧化物燃料电池阴极的要求。研究了以H2S为燃料气时,单体固体氧化物燃料电池(CoS-Mo2S)/BaCe0.9-xZrxY0.1O3/LSCF在不同温度下的电化学性能以及脱硫性能。结果表明:电池的最大电流密度、最大功率密度以及对H2S的脱除率均随温度的升高而增大;在反应温度为850℃,燃气流量为50 mL/min的条件下,电池的最大电流密度和最大功率密度分别为39.52 mA/cm2,6.38 mW/cm2;900℃时,H2S的脱除率达72%。     

可见光下钙钛矿LaCoO3光催化杀菌性能的应用研究

采用柠檬酸配合法制备纳米钙钛矿型LaCoO3及Sr掺杂的La0.9Sr0.1CoO3。在可见光下考察了催化剂浓度、菌液浓度对LaCoO3杀菌性能的影响。结果表明,在以30W日光灯为光源,距光源20cm处,辐照30min时,当菌液浓度为10^2～10^4cfu／mL,对大肠杆菌的杀菌率达90％以上,金黄色葡萄球菌46％。Sr掺杂后La0.9Sr0.1CoO3杀菌率分别可达98％,52％。通过XRD、SEM、DRS表征分析表明,催化剂粒径为60—80nm,在大于400nm的可见光区均有较好的吸收,Sr掺杂有助于提高杀菌效果。通过溶胶提拉法在瓷砖上附着钙钛矿膜,膜表面的杀菌率仍可保持在80％,40％以上。     

A Novel Membraneless Direct Hydrazine/Air Fuel Cell

In this paper multi‐walled carbon nanotubes (MWCNTs) supported binary AgNi nanoparticles are prepared by chemical reduction of Ag and Ni precursors with NaBH₄. Fe/PANI catalyst is obtained by direct pyrolysis of Fe‐doped polyaniline in N₂ atmosphere at high temperature. Results show that the Fe/PANI catalyst presents high electroactivity for oxygen reduction reaction (ORR) in alkaline media. The onset potential for ORR is 0.01 V(vs Hg/HgO) and the ORR current density is 3.4 mA cm⁻²@2000rpm at –0.4 V(vs HgO/Hg). A gas diffusion electrode is fabricated by using the Fe/PANI as the electrocatalyst of ORR. In alkaline media the AgNi/MWCNT catalyst displays efficient electroactivity for hydrazine oxidation. A lower onset potential of –0.5 V(vs Hg/HgO) and high current density for hydrazine oxidation are observed. A novel membrane‐less direct hydrazine/air fuel cell is designed by using the AgNi/MWCNT catalyst as the anode and the gas diffusion electrode as the cathode. The as‐fabricated fuel cell works properly and presents higher power density and current density.     

四元复合氧化物La_(0.5)Sr_(0.5)Ni_(0.5)Cu_(0.5)O_3的抗硫性能

以SO2 为毒物 ,采用脉冲中毒方法 ,再以CO氧化反应为探针 ,对三元复合氧化物催化剂La0 .5Sr0 .5NiO3 与La0 .5Sr0 .5CuO3 以及四元复合氧化物催化剂La0 .5Sr0 .5Ni0 .5Cu0 .5O3 等三种催化剂样品的抗硫毒能力、失活曲线、中毒催化剂的再生性能以及毒物残留形态等进行了全面考察和对比分析。实验结果表明四元复合氧化物催化剂La0 .5Sr0 .5Ni0 .5Cu0 .5O3 在SO2 毒物含量是 1 2 2×10 -2 mmol时 ,特别是在高温 (≥ 30 0℃ )条件下 ,具有优异的抗硫性能     

电化学制备Ba1-x Srx MoO4薄膜及其表征

采用恒电流电化学方法于室温条件下在金属钼片上制备白钨矿结构的Ba1-xSrxMoO4晶态薄膜；通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和X光电子能谱(XPS)对制备的薄膜进行了分析表征；探讨了Ba1-xSrxMoO4薄膜的成膜机制。结果表明，制备的Ba1-xSrxMoO4表面均匀致密，为四方单相薄膜。适宜的电化学制备工艺条件为电流密度1mA／cm^2，电解液的pH为13，电化学处理时间为1h。     

微量Ag掺杂对La_(0.6)Sr_(0.15)Na_(0.1)□_(0.15)MnO_3材料性质的影响

本文选用了La_(0.6)Sr_(0.15)Na_(0.1)□_(0.15)MnO_3(□为空位)为母体,用溶胶-凝胶方法制备了多晶样品Ag_(x-δ~-)La_(0.6)Sr_(0.15)Na_(0.1)Ag_δ□_(0.15-δ)MnO_3(x=0.00,0.016,0.04,0.1)。当x≥0.04时,其X光衍射谱上观察到了面心立方结构金属Ag相;掺杂样品的居里温度比未掺杂样品的要高,而且,随掺杂比例的增大而降低;掺杂样品在未加外磁场时的电阻率比未掺杂的要高,并随掺杂比例的增大而增大;当x=0.04时,MR在一个相当宽的温区内(207～286K)基本保持不变,即MR=(5.08±0.20)%,在一定程度上改善了母体样品MR的温度稳定性。     

MnO_2动态催化氧还原的研究

为了提高MnO2催化氧还原效率,采用B i改性MnO2经350℃高温处理后作为氧还原的催化剂,草酸铵造孔剂及MWNTs为复合电催化剂,氧电极可获得50 mA/cm2的工作电流密度(-200 mV)。B i改性MnO2的微观形貌分析表明,其晶体颗粒尺度约100 nm,且粒径分布较均匀,呈自然团聚外貌,团聚物直径在2~8μm。B i改性MnO2催化氧还原机理为:在放电过程中,由于B i改性的MnO2具有良好的可逆性能,因此O2在MnO2上发生的电子得失过程是瞬间过程,而不是MnO2的晶格转变,仅仅是质子-电子的传递。当缺氧时,MnO2发生还原反应,才会发生晶格转变。     

Studies on Me/Al-layered double hydroxides (Me = Ni and Co) as electrode materials for electrochemical capacitors

Me/Al-layered double hydroxides (Me=Ni and Co) prepared by the chemical co-precipitation method have been shown to be outstanding novel materials for electrochemical capacitors. The crystalline structure and the electrochemical properties of the electrodes have been studied by considering the effect of the mole ratio of nickel/cobalt. X-ray diffraction analysis shows that the materials belong to hexagonal system with layered structure. Cyclic voltammetric measurements indicate that Me/Al-layered double hydroxides with the Ni/Co mole ratio of 4:6 exhibit excellent capacitive properties within the potential range of 0.0-0.6 V versus Hg/HgO in 6 mol/L KOH electrolyte. Charge/discharge behaviors have been observed with the highest specific capacitance values of 960 F/g at the current density of 400 mA/g. Impedance studies show that the enhanced electrical properties and high frequency response are attributed to the presence of Co oxides.     

A binder‐free Ir0.4Ru0.6‐oxide/functionalized multi‐walled carbon nanotube electrode for possible applications in supercapacitors

An initial study on a simple and inexpensive method to form an Ir_0.4Ru_0.6‐oxide (MMO) coating onto high‐area plasma functionalized multi‐walled carbon nanotubes (f‐MWCNTs) at the bench‐scale for possible supercapacitor (SC) applications is presented. f‐MWCNT electrodes are prepared in a two‐step process combining the growth of MWCNTs directly onto a 316 stainless steel mesh by thermal‐chemical vapour deposition (t‐CVD), followed by the addition of oxygen‐containing functionalities to their surface by plasma functionalization. The plasma functionalization step is done to: (i) improve electrode wettability and (ii) improve capacitive properties through the addition of pseudocapacitive oxygen functionalities. A simple dip‐dry method is then employed to coat the f‐MWCNTs with the desired MMO coating (Ir_0.4Ru_0.6‐oxide) prepared initially in a liquid precursor mixture. f‐MWCNT electrodes are suspended and dipped into the precursor then heated in air to evaporate the solvent while building the oxide layer. The resulting MMO/f‐MWCNT electrode exhibits excellent stability in 4 mol/L KOH electrolyte, yielding larger specific capacitance values than those obtained on bare f‐MWCNT electrodes; at a charging/discharging current density of 0.5 mA cm^?2, the MMO/f‐MWCNT and f‐MWCNT electrodes achieve specific capacitances of 664 ± 7 and 190 ± 30 F g^?1 in a 3‐electrode cell, respectively. The MMO/f‐MWCNT electrodes show good rate capability performance up to 10 mA · cm^?2 and excellent stability.