应用于双功能型空气电极的钙钛矿型氧化物催化材料的研究

【作者】 温美盛；

【导师】 周德璧；

【作者基本信息】 中南大学 ， 应用化学， 2011， 硕士

【摘要】 钙钛矿型氧化物是一种应用于燃料电池空气电极的高效非贵金属催化剂,催化效果与其结构密切相关。本文工作研究了用溶胶-凝胶法制备钙钛矿型氧化物La0.5Sr0.5(LSCoO),首次采用了溶胶-微波法合成了掺杂碳材料的钙钛矿型氧化物La0.5Ca0.5CoO3/C (LSCoO/C),并测试它们在碱性介质(6mol·L-1KOH)中的电化学性能。采用溶胶-凝胶法制备了钙钛矿型氧化物LSCoO,其颗粒为不规则立方体,有轻微团聚,粒径在50-60nm之间。以此产物为催化剂制备的电极在空气气氛下碱性介质(6mol·L-1KOH)中,电位为-0.2 V(vs. HgO/Hg)时,催化氧还原的电流密度为152 mA·cm-2,电位在0.7 V (vs. HgO/Hg)时,催化氧析出的电流密度为152 mA·cm-2。以溶胶-微波法合成了LSCoO/C,其颗粒呈球形状,粒径在15～25 nm之间且分布均匀。以此催化剂制备的电极在空气气氛下碱性介质(6mol·L-1KOH)中,电位为-0.2 V (vs. HgO/Hg)时,催化氧还原的电流密度为157 mA·cm-2,电位在0.7 V (vs. HgO/Hg)时,催化氧析出的电流密度为142mA·cm-2。LSCoO、LSCoO/C的催化氧还原和氧析出的性能都很优越,且均优于5% wt Pt/C催化剂,可以作为双功能氧电极的催化材料。以催化剂LSCoO、LSCoO/C制备得到的空气电极作为电池的正极,组装成小型锌-空气电池,初步研究了电池的充放电性能。建立了O2在钙钛矿型氧化物CaTiO3(001)表面的吸附模型,以此来研究O2在其表面的吸附机理,并证实了氧缺陷表面有利于O2的吸附。更多还原

【Abstract】 Perovskite-type oxidation is a highly efficient non-noble metal catalyst of fuel cell oxygen electrode, the catalysis is closely relative to the structure. Perovskite-type oxidation La0.5Sr0.5CoO3(LSCoO) was prepared by sol-gel method,The perovskite La0.5Sr0.5CoO3/C (LSCoO/C) material was synthesized by sol-microwave method for the first time, whose electrochemical catalytic properties was also detected.Perovskite-type oxidation LSCoO was prepared by sol-gel method, The particles were spherical with the size of 50 to 60 nm. In alkaline electrolyte with reference potential of-0.2 V(vs. HgO/Hg), current density of catalytic ORR for the material under condtions of air, was 152 mA·cm-2 respectively, and 152 mA·cm-2 for catalytic OER at 0.7 V (vs. HgO/Hg).The LSCoO/C was synthesized by sol-microwave method, The particles were spherical with the size of 15 to 25 nm and had a well distribution and morphology.In alkaline electrolyte with reference potential of-0.2 V(vs. HgO/Hg), current density of catalytic ORR for the material under condtions of air, was 157 mA·cm-2 respectively, and 142 mA·cm-2 for catalytic OER at 0.7 V (vs. HgO/Hg). It suggests LSCoO,LSCoO/C has higher performance on catalytic ORR and OER than the precious metal 5%wtPt/C catalyst, and therefor it can act as a catalytic material of bifunctional oxygen electrode.A simple zinc-air fuel cell was manufactured, with LSCoO,LsCoO/C being used as the catalyst for air diffusion electrode. We investigate the charge and discharge performance of the cell preliminarily.Present research also established a model that O2 adsorbs in CaTiO3(001), in order to explan the mechanism for O2 adsorbing in surface of CaTiO3(001), One model was established in this paper.It confirmed that the oxygen deficiency is more conducive to the surface adsorption of O2 molecules.更多还原