催化学报 ›› 2016, Vol. 37 ›› Issue (8): 1249-1256.DOI: 10.1016/S1872-2067(16)62462-2

• 论文 • 上一篇    下一篇

氧还原和析氧反应的双功能电催化剂——氮磷共掺碳负载四氧化三钴

黄颖彬a,b, 张敏a, 柳鹏a, 程发良a, 王立世b   

  1. a. 东莞理工学院广东省新型纳米材料工程技术研究中心, 广东 东莞 523808;
    b. 华南理工大学化学与化工学院, 广东 广州 510640
  • 收稿日期:2016-01-21 修回日期:2016-05-03 出版日期:2016-07-29 发布日期:2016-08-01
  • 通讯作者: Faliang Cheng, Lishi Wang
  • 基金资助:

    国家自然科学基金(21375016,20475022,21505019).

Co3O4 supported on N, P-doped carbon as a bifunctional electrocatalyst for oxygen reduction and evolution reactions

Yingbin Huanga,b, Min Zhanga, Peng Liua, Faliang Chenga, Lishi Wangb   

  1. a. Guangdong Engineering and Technology Research Center for Advanced Nanomaterials, Dongguan University of Technology, Dongguan 523808, Guangdong, China;
    b. School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, Guangdong, China
  • Received:2016-01-21 Revised:2016-05-03 Online:2016-07-29 Published:2016-08-01
  • Contact: Faliang Cheng, Lishi Wang
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21375016, 20475022 and 21505019).

摘要:

金属-空气电池具备诸多优势,譬如绿色环保、能量转化率高、启动快速、能量密度高、使用寿命和干态存储时间长等.与燃料电池相比,金属-空气电池结构简单,放电电压平稳,成本低,但依然存在一些制约发展的问题,如阴极催化剂.阴极催化剂在金属-空气电池中发挥催化氧还原反应(oxygen reduction reaction,ORR)和析氧反应(oxygen evolution reaction,OER)的关键作用.铂及其合金常用作ORR的单功能催化剂,而钌和铱等是目前OER催化效率最高的,但ORR活性很低,因此需要开发出一种廉价而又具备双功能催化作用的催化剂.单异原子掺杂的碳基催化剂的研究集中在ORR催化性能上,而多异原子共掺碳最近有研究表明具有双催化氧的性质,如氮磷共掺碳.在这些氮磷共掺的碳架中,氮磷共掺物起着OER催化作用,掺氮物为ORR催化的活性位点,而掺磷物起着强化作用.异原子掺杂负载的钴基催化剂(如掺氮还原氧化石墨烯载Co3O4)是近年来双功能催化剂研究的另一个热点.钴基催化剂有着催化ORR和OER的多价价态,然而其本身导电性能差,这一缺陷可通过杂化石墨化碳来弥补,石墨化碳有着优良的导电性能.据我们所知,目前仍没有关于氮磷共掺碳负载的Co3O4双催化氧的研究.我们合成了氮磷共掺碳(NPC)负载的Co3O4(Co3O4/NPC),并首次探索了其氧还原和析氧性能.Co3O4/NPC合成分两步进行.首先通过三聚氰胺与植酸之间的酯化或缩聚覆盖在导电炭黑颗粒表面,在保护气氛下焙烧得到NPC,然后经溶剂热反应以及空气中氧化合成Co3O4/NPC.催化剂的性能综合考虑了催化活性和稳定性两方面.采用线性扫描伏安法评估了OER和ORR的催化活性.对于OER,Co3O4/NPC的起始电势是0.54V(以饱和甘汞电极为参比电极),在0.80V时电流密度达到21.95mA/cm2,均优于Co3O4/C和NPC.Co3O4/NPC的高效OER催化可归因于氮磷共掺物与Co3O4之间的协同作用.对于ORR,Co3O4/NPC的催化效率与商用Pt/C相近,它们的扩散极限电流密度分别为-4.49和-4.76mA/cm2E=-0.80V).在ORR过程中,Co3O4起到主要的催化作用.采用计时电流(电流-时间)法评估了催化剂的稳定性.经6h测定,对于OER,Co3O4/NPC剩46%电流;而对于ORR,剩95%电流.整体而言,Co3O4/NPC在OER和ORR中都表现出高的催化效率以及良好的稳定性.

关键词: 阴极催化剂, 氧还原反应, 析氧反应, 掺杂碳,

Abstract:

Noble metals, such as platinum, ruthenium and iridium-group metals, are often used as oxygen reduction or evolution reaction (ORR/OER) electrocatalysts. To reduce the cost and provide an application of bifunctional catalysis, in this work, cobalt oxide supported on nitrogen and phosphorus co-doped carbon (Co3O4/NPC) was fabricated and examined as a bifunctional electrocatalyst for OER and ORR. To prepare Co3O4/NPC, NPC was pyrolyzed from melamine and phytic acid supported on carbon, followed by the solvothermal synthesis of Co3O4 on NPC. Linear sweep voltammetry was used to evaluate the activity for OER and ORR. For OER, Co3O4/NPC showed an onset potential of 0.54 V (versus the saturated calomel electrode) and a current density of 21.95 mA/cm2 at 0.80 V, which was better than both Co3O4/C and NPC. The high activity of Co3O4/NPC was attributed to a synergistic effect of the N, P co-dopants and Co3O4. For ORR, Co3O4/NPC exhibited an activity close to commercial Pt/C in terms of the diffusion limited current density (-4.49 vs -4.76 mA/cm2 at -0.80 V), and Co3O4 played the key role for the catalysis. Chronoamperometry (current versus time) was used to evaluate the stability, which showed that Co3O4/NPC maintained 46% current after the chronoamperometry test for OER and 95% current for ORR. Overall, Co3O4/NPC exhibited high activity and improved stability for both OER and ORR.

Key words: Cathode catalyst, Oxygen reduction reaction, Oxygen evolution reaction, Doped carbon, Cobalt