可逆单部件燃料电池双功能催化剂La0.5Sr0.5Co0.2Fe0.8O3的制备及电化学性能研究

Preparation and electrochemical properties of La0.5Sr0.5Co0.2Fe0.8O3 oxides as bifunctional catalysts for reversible single-component cells

  • 摘要: 利用SBA-15硬模板合成La0.5Sr0.5Co0.2Fe0.8O3 (LSCF)钙钛矿材料,通过研究LSCF的电化学性能,探究制备溶剂(甲醇/乙醇)对LSCF结构、表面性质及电化学性能的影响。结果表明,乙醇溶剂制备的LSCF具有更大的比表面积和更多的氧空位浓度,从而表现出更高的电导率以及对氧还原反应(ORR)和氢氧化反应(HOR)更好的催化活性。这是因为乙醇溶剂制备的LSCF具有更多的Co2 + /Co3 + 和Fe2 + /Fe3 + 电子对,促进了材料的电子传导。此外,对于HOR,电极反应的速率控制步骤(RDS)是吸附的氢原子转移到反应位点;吸附的氧原子在LSCF上的还原是ORR反应的RDS。此外,由乙醇溶剂制备的LSCF组成的可逆单部件电池(RSCC)具有更好的放电和电解水性能。700 ℃,H2-30%H2O燃料下,RSCC的最大功率密度为232.9 mW/cm2,并且在1.3 V的电解电流密度为−398.3 mA/cm2

     

    Abstract: La0.5Sr0.5Co0.2Fe0.8O3 (LSCF) perovskite materials were prepared by hard template method with SBA-15 as the template in methanol and ethanol solvents and the electrochemical properties of LSCF were investigated. It is found that LSCF prepared with ethanol solvent has larger specific surface area and more oxygen vacancy concentration, which in turn exhibits higher electrical conductivity and better catalytic activity towards oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR). This is because the LSCF prepared by the ethanol solvent has more Co2 + /Co3 + and Fe2 + /Fe3 + electron pairs, which promotes the electronic conduction of the material. In addition, for HOR, the rate determining step (RDS) is the transfer of adsorbed H to the reaction site, and for ORR, the RDS is the reduction of the adsorbed oxygen atom on LSCF. In addition, the reversible single-component cell (RSCC) composed of LSCF prepared by ethanol solvent shows better performance for discharge and water electrolysis. The maximum power density (Pmax) of the RSCC is 232.9 mW/m2, and the current density at 1.3 V is −398.3 mA/cm2 at 700 ℃.

     

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