【作者】 孙仁兴；

【导师】 王佳； 徐海波；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2007， 硕士

【摘要】 首次以纳米TiN粉体为前驱体反应物,采用浸渍-热分解法制备了IrOx-TiO₂和RuO₂-TiO₂纳米粉体,采用电化学测试技术和物性分析手段对其析氢、析氧电催化活性和结构进行了研究,比较了IrOx-TiO₂与传统贵金属催化剂的电催化活性和稳定性,初步探讨了以RuO₂-TiO₂为载体的Pt/RuO₂-TiO₂粉体催化剂在SPE（Solid Polymer Electrolytes）水电解和质子交换膜燃料电池（ PEMFC）领域的应用前景。IrOx-TiO₂水电解用纳米粉体催化剂:（1）XRD、XPS、TEM分析表明:在350℃的热分解温度下,纳米TiN转化为金红石相TiO₂,铱则以多种价态存在,与TiO₂形成二元氧化物固溶体,并且在固溶体表面存在富集Ir的颗粒,其平均粒径约7nm。（2）极化曲线测试表明,TiN浸渍-热分解法制备的IrOx-TiO₂粉体催化剂,在析氢、析氧催化活性方面超过了纯IrO₂粉体。（3）SPE水电解:将500℃退火处理的IrOx-TiO₂粉体作为析氧阳极催化剂在SPE水电解中的的测试表明,其具有很高的电催化性能,在铱担载量为1.2mgcm-2,电解温度80℃,工作电流密度1Acm-2下,槽压为1.6V。RuO₂-TiO₂为载体的Pt催化剂用于水电解和质子交换膜燃料电池:（1）XRD和TEM分析表明:采用TiN浸渍-热分解法制备的混和氧化物RuO₂-TiO₂,以金红石相的固溶体形式存在,外貌呈条状,长度在40nm⁸0nm;Pt/RuO₂-TiO₂中的Pt与RuO₂-TiO₂载体发生相互作用,Pt颗粒均匀沉积在载体表面,粒径为2³nm。（2）析氢阴极极化曲线测试表明,在高电流密度下Pt/RuO₂-TiO₂的电阻极化要比Pt/C小得多,说明RuO₂-TiO₂比碳载体具有更好的导电性能。（3）在质子交换膜燃料电池中的测试表明,Pt/RuO₂-TiO₂催化性能与Pt/C相当,但在甲醇溶液中的循环伏安测试表明,Pt/RuO₂-TiO₂具有很好的耐甲醇特性。（4）反极实验证明与Pt/C相比,Pt/RuO₂-TiO₂具有极高的稳定性,可大幅度提高电池的耐久性。上述实验结果表明首次采用的TiN浸渍-热分解法制备的纳米粉体催化剂在水电解和质子交换膜燃料电池领域将有着非常好的发展前景,值得进一步深入研究。更多还原

【Abstract】 Nano IrOx-TiO₂ catalyst with a Ir:Ti atomic ratio of 1:6.5 had been synthesized from the TiN nano-particle precursors via the impregnation-thermal decomposition method. Electrochemical tests and material analyses had been used to investigate their morphological structure, electrocatalytic activity. The electrocatalytic activity and stability of the powder catalyst of IrOx-TiO₂ had been compared with traditional noble metal catalyst. Pt /RuO₂-TiO₂ with Pt supported on nanoparticle RuO₂-TiO₂ had been studied primarily for PEMFC and water electrolysis with SPE （Solid Polymer Electrolytes） technology. The main conclusions were as follows:In case of IrOx-TiO₂ powder catalyst for water electrolysis:（1）The XRD、XPS、TEM results showed that TiN had been converted to TiO₂ rutile-type phase at 350℃and Ir presented as multi-value oxides. TiO₂ and IrOx formed a binary solid solution in a rutile phase. A great number of Ir particles with an average crystal size of about 7nm were rich in the surface of the solid solution.（2）Polarization curves showed that the electrocatalytic activity of nano IrOx-TiO₂ catalyst synthesized from the TiN nano-particle precursors via the impregnation-thermal decomposition method was better than traditional impregnation method . The activity for oxygen evolution and hydrogen evolution also was superior to that of pure IrO₂.（3）The catalyst of IrOx-TiO₂ annealed at 500℃have been examined as oxygen evolution electrocatalysts for SPE water electrolysis and high performance has been achieved. The electrolytic voltage was 1.6V at 1Acm-2 and 80℃, with Ir loading of only 1.2 mgcm-2.These results suggest that this new method is an efficient way to synthesize noble metal oxides catalyst with high activity and low cost for water electrolysis. In case of Pt supported RuO₂-TiO₂ powder catalyst for water electrolysis and fuel cell:（1）The XRD、TEM results showed that RuO₂-TiO₂ has been synthesized from the TiN nano-particle precursors via the impregnation-thermal decomposition method, TiO₂ and RuO₂ formed a binary solid solution in a rutile phase. The size of Pt/RuO₂-TiO₂ nano-particles was about 20nm³0nm, and demonstrated that Pt had been highly dispersed on RuO₂-TiO₂ substrates.（2）Cathode polarization curves showed that its ohmic polarization was very lower than that of Pt/C, and demonstrated that RuO₂-TiO₂ had high conductivity.（3）Pt/RuO₂-TiO₂ powder catalyst applied on PEM fuel cell exhibited high activity as good as Pt/C. Cyclic polarization curves of Pt/RuO₂-TiO₂ in 0.5 mol/L H2SO4 +0.5 mol/L CH3OH solution indicated such catalyst had low electrochemical activities with CH3OH, and decreased the side reaction.（4）Reverse polarity experiments showed that Pt/RuO₂-TiO₂ has excellent stability, and that can consequently prolong life time of the fuel cell.This kind of catalyst is so promising that deserved further research.更多还原