Abstract:

Hydrolysis of borohydride is one of the major problems leading to a decrease in the fuel efficiency of direct borohydride fuel cell (DBFC). Co₃O₄ was first used as DBFC anode catalyst and to reduce the hydrolysis reaction by silver plating treatment. Co₃O₄ was prepared by using CoCl₂·6H₂O and silvered on its surface by silver mirror reaction to obtain Co₃O₄@Ag. The physics properties of the catalyst were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS). The electrochemical properties were investigated by electrochemical impedance spectroscopy (EIS), chronoamperometry (CA) and fuel cell test. The characterizations demonstrate that Ag was successfully introduced into the catalyst system by silver mirror reaction and account for 2% of the Co₃O₄@Ag catalytic material. Electrochemical tests showed that Co₃O₄@Ag had a higher electro-catalytic activity than Co₃O₄. The maximum power density (55 mW·cm^-2) and specific capacity (971 mA·h·g^-1) of fuel cell, which was fabricated by using Co₃O₄@Ag as anode catalyst, increased by 44.7% and 32.1%, respectively than Co₃O₄ at room temperature. The performance of anode catalyst was significantly increased. Ag reflected the synergistic catalytic effect with Co₃O₄ when it inhibited the hydrolysis reaction.

Key words: electrochemistry, fuel cells, anode catalyst, sliver plating treatment, hydrolysis

摘要：

硼氢化物水解是导致直接硼氢化物燃料电池（DBFC）燃料效率下降的主要问题之一。将Co₃O₄用于DBFC阳极催化剂并通过镀银处理以降低水解反应。以CoCl₂·6H₂O为原料制备Co₃O₄，并通过银镜反应对其进行镀银处理，制得Co₃O₄@Ag。通过X射线衍射（XRD）、扫描电子显微镜（SEM）和能谱（EDS）对其进行物理表征，通过交流阻抗（EIS）、计时电流（CA）和电池测试对其电化学性能进行表征。结果表明，利用银镜反应成功地将Ag引入到催化剂体系，且Co₃O₄@Ag催化材料的含银量为2%。电化学测试表明，与Co₃O₄相比Co₃O₄@Ag具有更高的电催化活性。以Co₃O₄@Ag为阳极催化剂组装的燃料电池在室温下最大功率密度（55 mW·cm^-2）和比容量（971 mA·h·g^-1）较Co₃O₄分别提高了44.7%和32.1%，阳极催化剂性能得到显著提高。Ag在抑制水解反应的同时与Co₃O₄体现了协同催化的作用。

关键词: 电化学, 燃料电池, 阳极催化剂, 镀银处理, 水解