催化学报 ›› 2020, Vol. 41 ›› Issue (5): 858-867.DOI: 10.1016/S1872-2067(19)63507-2

• 论文 • 上一篇    下一篇

基于氮掺杂碳载铁复合物的锌空电池氧阴极催化剂

陈凯a,b, 次素琴a, 许秋华a, 蔡平伟b, 李美珍a, 向利娟a, 胡茜a, 温珍海b   

  1. a 南昌航空大学, 江西省持久性污染物控制与资源循环利用重点实验室, 江西南昌 330063;
    b 中国科学院福建物质结构研究所, 中科院功能纳米材料结构与组装重点实验室, 福建省纳米材料重点实验室, 福建福州 350002
  • 收稿日期:2019-10-12 修回日期:2019-11-10 出版日期:2020-05-18 发布日期:2019-12-31
  • 通讯作者: 次素琴, 温珍海
  • 基金资助:
    国家自然科学基金(21566025,21875253);江西省杰出青年学者科学基金(20162BCB23044);江西省研究生创新专项基金(YC2018-S362).

Iron-incorporated nitrogen-doped carbon materials as oxygen reduction electrocatalysts for zinc-air batteries

Kai Chena,b, Suqin Cia, Qiuhua Xua, Pingwei Caib, Meizhen Lia, Lijuan Xianga, Xi Hua, Zhenhai Wenb   

  1. a Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, Jiangxi, China;
    b CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, Fujian, China
  • Received:2019-10-12 Revised:2019-11-10 Online:2020-05-18 Published:2019-12-31
  • Contact: S1872-2067(19)63507-2
  • Supported by:
    The work was supported by the National Natural Science foundation of China (21566025, 21875253), the Science Fund of Jiangxi Province for Distinguished Young Scholars (20162BCB23044), and the Jiangxi Provincial Graduate Innovation Special Fund Project (YC2018-S362).

摘要: 迫在眉睫的环境和能源问题推动人类探索可行、可靠和可再生的能源技术.锌-空气电池和氢氧燃料电池等器件显示出高能量转换效率,但是仍有许多难题有待克服,例如阴极侧上缓慢的氧还原反应(ORR),以及高昂的成本极大地限制了铂基催化剂在商业上的广泛应用.因此,开发高性能的廉价ORR催化剂具有重要意义.过渡金属碳氮化合物(M-N-C,M=Co,Fe等)成为最有希望替代铂基催化剂的一类材料,M-N-C催化剂可以通过直接热解含有过渡金属、氮和碳物种的前驱体合成.然而热解时金属原子易团聚,多孔结构不能被有效地控制,导致相对较差的催化活性.目前,MOF衍生的催化剂在能源转化和储存技术中得到了广泛的关注,其具有丰富的氮含量、高比表面积和可调的孔道结构等特点.本文报道了一种简便可靠可控的合成铁氮共掺杂碳十二面体纳米结构催化剂的方法,并作为阴极电催化剂用于锌空气电池中,测试结果证实,合成的铁氮共掺杂的纳米碳具有与铂基材料相当的活性和更加优异的稳定性.
表面吸附了的邻菲罗啉铁的ZIF-8在碳化过程中,氮基团能够结合铁形成FeNx结构单元,因此可得到铁氮共掺杂的电催化剂.粉末X射线衍射,扫描电镜证实ZIF-8的成功合成.经过热解得到的催化剂中FeNx或FeCx衍射峰较弱,表明样品中铁含量较低,存在部分无定型铁.通过拉曼光谱分析发现,引入的邻菲罗啉在热解过程中诱导了缺陷的形成,所以Fe-NCDNA-0的ID/IG比值明显高于NC.同时ID/IG随着铁含量的增加而减少,这是因为铁可以诱导石墨化,诱导效应随着铁含量的增加而增加.分析氮气吸附-脱附等温线得出,引入邻菲罗啉之后,比表面积增加;而铁的引入因其占据了微孔结构,导致比表面积下降.同时电镜证实Fe-NCDNA-2具有较大的形貌扭曲,使得该材料具有较大的比表面积.
系统的电化学研究表明,氮掺杂有利于增强ORR活性,在引入铁之后形成高效的活性中心会进一步提高催化性能.因此,Fe-NCDNA-2在碱性条件下表现出优异的ORR性能.线性扫描伏安法曲线表明,铁氮共掺杂的材料表现出与Pt/C相似的性能,其中Fe-NCDNA-2的半波电位(E1/2)为0.863V,比商业Pt/C的电位更正(E1/2=0.841V).同时,Fe-NCDNA-2具有更加优异的稳定性,测试30000s后的电流保持率为80%(Pt/C:64%).在中性介质中,合成的材料也展示了较高的ORR活性.Fe-NCDNA-2的E1/2=0.715V,催化30000s后电流保持率77%,均优于商业Pt/C催化剂.组装的锌空气电池进一步验证其作为氧还原催化剂实际应用的可行性.相比于以Pt/C为催化剂做空气阴极的电池,以Fe-NCDNA-2组装的电池表现出更高的开路电压,更高的功率密度(184mW cm-2),以及更加优异的充放电循环稳定性.该工作也有利于启发研究人员探索类似的氮掺杂过渡金属碳材料在各种催化上的应用.

关键词: 氧还原反应, 电催化剂, Fe-N-C活性位点, 碱性/中性介质, 锌空气电池

Abstract: The application of electrocatalysts for the oxygen reduction reaction (ORR) is vital in a variety of energy conversion technologies. Exploring low-cost ORR catalysts with high activity and long-term stability is highly desirable, although it still remains challenging. Herein, we report a facile and reliable route to convert ZIF-8 modified by Fe-phenanthroline into Fe-incorporated and N-doped carbon dodecahedron nanoarchitecture (Fe-NCDNA), in which carbon nanosheets are formed in situ as the building blocks with uniform Fe-N-C species decoration. Systematic electrochemical studies demonstrate that the as-synthesized Fe-NCDNA electrocatalyst possesses highly attractive catalytic features toward the ORR in terms of activity and durability in both alkaline and neutral media. The Zn-air battery with the optimal Fe-NCDNA catalyst as the cathode performs impressively, delivering a power density of 184 mW cm-2 and a specific capacity of 801 mAh g-1; thus, it exhibits great competitive advantages over those of the Zn-air devices employing a Pt-based cathode electrocatalyst.

Key words: Oxygen reduction reaction, Electrocatalyst, Fe-N-C activity sites, Alkaline/neutral medium, Zn-air battery