纳米四氧化三钴催化剂的制备及其电催化性能

四氧化三钴（Co3O4）作为一种重要的电极催化材料，具有催化活性高，价格低廉等特点，可有效解决过度依赖储量少，成本高的Pt系贵金属催化剂等问题。实验采用化学沉淀法结合热分解法，以Co(NO3)2·6H2O为钴源,沉淀剂为NH4HCO3，聚乙二醇（PEG）为表面活性剂，在45℃条件下反应，分别选择室温和水热环境陈化处理，洗涤干燥后，350 ℃的马弗炉里煅烧3 h，通过调控陈化场所和时间可制备出块状、球状及杆状的Co3O4,其中球状的最小粒径达8.54 nm，然后把制备出均相高纯度的Co3O4作为直接甲醇燃料电池阴极催化剂来测试电催化活性，结果显示Co3O4具有良好的电催化性能，在1 mol/L的KOH的氧化还原峰的电位1.34 V,比商用Pt/C(20 wt%)的高0.05 V。在氧气饱和的1 mol/L的KOH电介质溶液中加入20000 ppm的无水甲醇，250s后两种材料的电流密度衰减为0.0051 mA/cm2与0.0136 mA/cm2，半波电位分别为1.025 V和1.113 V，虽然Co3O4的催化活性不及Pt/C(20 wt%)材料，但对甲醇的耐受性及稳定性要优于商用Pt/C(20 wt%)材料。

Preparation and Electrocatalytic Performance of Nanometer Cobalt Tetroxide Catalysts

As an important electrode catalytic material, cobalt trioxide (Co3O4) has the characteristics of high catalytic activity and low price, which can effectively solve the problems of over-dependence on the precious metal catalysts of Pt series with low reserves and high cost. In the experiment, the chemical precipitation method combined with thermal decomposition method, Co(NO3)2·6H2O as cobalt source, precipitator NH4HCO3 and PEG as surfactant, were used for reaction at 45℃, and were aged at room temperature and hydrothermal environment respectively. After washing and drying, they were calcined in Muffle furnace at 350 ℃ for 3 h. By adjusting the aging time, bulk, spherical and rod-shaped Co3O4 can be prepared, and the minimum particle size of the spherical is 8.54 nm. Then the homogeneous and high-purity Co3O4 is prepared as the cathode catalyst of direct methanol fuel cell to test the electrocatalytic activity. The results show that Co3O4 has good electrocatalytic performance. The ORR peak potential of 1 mol/L KOH was 1.34 V, which was 0.05 V higher than that of commercial Pt/C(20 wt%). After adding 20000 ppm of anhydric methanol to the oxygen-saturated 1mol/L KOH dielectric solution, the current density of the two materials decays to 0.0051 mA/cm2 and 0.0136 mA/cm2 after 250s, and the half-wave potential is 1.025 V and 1.113 V, respectively. Although the catalytic activity of Co3O4 is not as good as that of Pt/C(20 wt%) material, the tolerance and stability of Co3O4 to methanol is better than that of commercial Pt/C(20 wt%) material.