Fe/Co/N/MWCNTs催化剂的制备及性能

Preparation and Electrochemical Activity of Fe/Co/N/MWCNTs Catalysts for Oxygen Reduction Reaction

将掺杂铁离子的聚苯胺(PANI)与碳纳米管(MWCNT)复合物在900℃加热,得到含铁的催化剂FeNC;然后将含钴盐的FeNC在不同温度下焙烧,得到复合催化剂FeCoNC。对催化剂的表观结构、比表面积、热稳定性、组成以及氧还原(ORR)电催化活性进行表征,研究了焙烧温度和氮含量等因素对其催化活性的影响。结果表明:随着焙烧温度的升高,催化剂的表面结构趋于均匀,焙烧温度为500℃的催化剂表面结构最为均匀平整,高于500℃时出现烧结;较高的氮含量能改善催化剂的ORR电活性。焙烧温度为500℃的催化剂对ORR的电催化活性最高,在酸性和碱性溶液中ORR的起始电位分别为0.63和-0.12 V(vs SCE),电流密度分别为11.67和9.83 mAmg-1@-0.3 V(vs SCE),并具有较好的热稳定性和催化活性稳定性。分步加入Fe和Co,并在加Co后在500℃焙烧得到的催化剂对ORR具有优异的电催化活性。

MWCNTs doped polyaniline （PANI） were used as a precursor and the precursor added Fe salt was heated at 900℃ to obtain the Fe-containing catalyst FeNC. Cobalt salt was then added to the FeNC and the mixture was subjected to heat treatment at different temperatures to prepare the various composites FeCoNC. The structure, specific surface area, thermal stability and compositions of the cata- lysts FeCoNC were characterized by TEM, SEM, TGA and elemental analysis, respectively. The results show that the catalyst structure becomes uniform when the temperature is 500℃, and it appears sinter- ing at the temperature higher than 500℃. The content of N increases first and then decreases with the in- creasing of temperature. The temperature has a little influence on the specific surface area of the cata- lysts. TGA suggests that the catalysts have good thermal stability in the air. ORR activity of the catalysts has been tested by CV and RDE techniques. Results show that the catalyst FeCoNC5 obtained by the heating treatment at 500℃ presents the highest electrocatalytic activity for ORR. The ORR current densi- ty at 2000r/min is 11.67 mA/mg@-0.3 V（vs SCE） in acidic solution and 9.83 mA/mg@-0.8 V（vs SCE） in alkaline solution, and the onset potential of ORR is 0.63 V（vs SCE） in acidic solution and-0.12 V（vs SCE） in alkaline solution.