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燃料电池具有较高的能量密度和发电效率,以清洁能源为原料,零污染排放,是一种具有发展前景的能量储存和转化装置.阴极氧还原反应(ORR)在燃料电池中起着关键作用.ORR广泛采用贵金属铂基催化剂,但是它们价格昂贵,电子动力学转移速率慢,碱性条件下易团聚,这些亟需解决的问题阻碍了燃料电池商业化进程.近期,一些非贵金属催化剂被广泛研究,例如氮掺杂碳材料、Fe/N/C和Co/N/C材料等,它们有可能在未来替代铂基催化剂.我们的目标是合成新型高催化活性的Co/N/C及其衍生非贵金属材料,用于ORR催化反应.由于石墨烯具有独特的形貌、较大的比表面积和良好的导电性,其表面含有功能化的官能团,所以我们选择石墨烯作为碳载体.首先,用改性休克尔方法合成了氧化石墨烯(GO),为了提高其催化活性,采用聚吡咯作为氮源对其进行了氮掺杂,制备了聚吡咯/氧化石墨烯(Ppy/GO).通过ORR催化性能测试发现,GO对ORR具有一定的催化活性,它的起始电位和阴极电流电位分别为–0.31 V vs SCE和–0.38 V vs SCE;Ppy/GO的起始电位和阴极电流电位分别为–0.20 V vs SCE和–0.38 V vs SCE,氮掺杂对GO的催化活性有所提高.采用水热法沉积氧化钴合成了Co_3O_4/聚吡咯/氧化石墨烯(Co_3O_4/Ppy/GO).其形貌为Co_3O_4分散在氮掺杂GO表面.在KOH电解质(0.1 mol/L)中测试,Co_3O_4/Ppy/GO的起始电位和阴极电流电位分别为–0.20 V和–0.38 V vs SCE.经过800°C高温煅烧处理后,Co_3O_4/Ppy/GO-800的催化活性明显提高,起始电位和阴极电流电位分别达到–0.10 V和–0.18 V vs SCE.ORR电子转移数为3.4,接近于4电子反应途径.Co_3O_4/Ppy/GO对ORR的催化活性及4电子催化选择性较高,可能是由于纳米形态的Co_3O_4和Ppy/GO之间具有较强的表面作用力,聚吡咯掺杂的氧化石墨烯具有较强的电子储存及释放能力.综上,我们通过水热法制备了钴、氮共掺杂的GO,并研究了其对ORR的催化活性和电子转移选择性.结果表明Co_3O_4/Ppy/GO是一种高效的非贵金属电催化剂,在碱性电解质中具有很高的ORR催化活性,在燃料电池阴极催化剂方面很有前景.
Fuel cell with high energy density and power generation efficiency, clean energy as raw material, zero pollution emissions, is a promising energy storage and conversion device. Cathodic oxygen reduction reaction (ORR) plays a key role in the fuel cell .ORR widespread use of precious metal platinum-based catalysts, but they are expensive, slow electron transfer rate, easy to agglomerate under alkaline conditions, these problems need to be solved impede the commercialization of fuel cells.Recently, some non-precious metal catalysts are widely Research, such as nitrogen-doped carbon materials, Fe / N / C and Co / N / C materials, which are likely to replace platinum-based catalysts in the future.Our goal is to synthesize new highly catalytically active Co / N / C and its Derivatization of non-noble metal for ORR catalytic reaction.We chose graphene as the carbon support due to its unique morphology, large specific surface area and good electrical conductivity, and its surface contains functionalized functional groups.Firstly, Graphene oxide (GO) was synthesized by a modified Shucker method. In order to improve its catalytic activity, polypyrrole was used as a nitrogen source to do nitrogen doping. Polypyrrole / graphene oxide (Ppy / GO ). The catalytic activity of ORR showed that GO had some catalytic activity on ORR with initial potential and cathodic current potential of -0.31 V vs SCE and -0.38 V vs SCE, respectively. The initial potential of Ppy / GO and the cathode The current potentials were -0.20 V vs SCE and -0.38 V vs SCE, respectively, and the catalytic activity of GO was improved by nitrogen doping.Co_3O_4 / polypyrrole / graphene oxide (Co_3O_4 / Ppy / GO) .The morphology of Co_3O_4 was dispersed on the surface of nitrogen-doped GO.The initial and cathodic current potentials of Co_3O_4 / Ppy / GO were -0.20 V and -0.38 V, respectively, in KOH electrolyte (0.1 mol / L) vs SCE. After calcination at 800 ° C, the catalytic activity of Co_3O_4 / Ppy / GO-800 was significantly improved, the initial potential and cathodic current potential reached -0.10 V and -0.18 V vs SCE, respectively. The ORR of electron transfer was 3.4 , Which is close to the 4-electron reaction pathway.CoO_3O_4 / Ppy / GO has higher ORR selectivity and higher selectivity for 4-electron catalysis, probably due to the stronger surface forces between Co_3O_4 and Ppy / GO nanostructures, Doped graphene oxide has a strong electronic storage and release capacity.In summary, we through the water Cobalt and nitrogen co-doped GO were prepared by thermal method, and their catalytic activity and electron transfer selectivity to ORR were studied. The results show that Co_3O_4 / Ppy / GO is an efficient non-noble metal electrocatalyst. In alkaline electrolyte It has a high ORR catalytic activity and is promising for fuel cell cathode catalysts.