Synergistically enhanced activity of nitrogen-doped carbon dots/graphene composites for oxygen reduction reaction
Synergistically enhanced activity of nitrogen-doped carbon dots/graphene composites for oxygen reduction reaction
复制标题
协同增强氮掺杂碳点/石墨烯复合材料的氧还原反应活性
DOI：
10.1016/j.apsusc.2017.06.225
复制
发表时间：
2017-11-30
影响因子：
6.7
通讯作者：
Wu, Mingbo
中科院分区：
文献类型：
--
作者：
Liu, Hui;Zhao, Qingshan;Wu, Mingbo
氮掺杂碳纳米材料具有快速解离吸附氧的特性，是燃料电池中氧还原反应（ORR）的高效替代催化剂。在此，我们开发了一种温和的水热策略来构建氮掺杂碳点/石墨烯（NCDs-NG）复合材料。以石油焦为原料，采用酸氧化法制备了碳点（CDs），采用改进的Hummer法制备了氧化石墨烯（GO）。在水热还原反应中，石墨烯作为导电衬底分散CDs，氨作为氮源掺杂石墨烯和CDs。CDs作为石墨烯的支柱和ORR的催化位点的协同效应，石墨烯的高导电性，掺杂吡啶氮对O-2的快速吸附，使NCDs-NG复合材料在碱性电解质中具有增强的ORR催化性能。在-0.7 V（相对于Ag/AgCl）下，-95 mV的起始电位和12.7 mA cm（-2）的动态电流密度可以与20 wt% Pt/C的商用催化剂相比较。电子转移数约为3.9，揭示了ORR的四电子途径。最佳的NCDs-NG催化剂比20% Pt/C具有更好的耐久性和甲醇耐受性。本研究为燃料电池制备无金属高效ORR电催化剂提供了一种可行和有效的策略。(C) 2017 Elsevier B.V.版权所有
With rapid dissociative adsorption of oxygen, nitrogen-doped carbon nanomaterials have been demonstrated to be efficient alternative catalysts for oxygen reduction reaction (ORR) in fuel cells. Herein, we developed a mild hydrothermal strategy to construct nitrogen-doped carbon dots/graphene (NCDs-NG) composites towards ORR. Carbon dots (CDs) were derived from petroleum coke via acid oxidation while graphene oxide (GO) was obtained from graphite by modified Hummer's method. Graphene was employed as a conductive substrate to disperse CDs during hydrothermal reducing reaction while ammonia was utilized as N source to dope both graphene and CDs. The synergistic effects, i.e. CDs as pillars for graphene and catalytic sites for ORR, the high conductivity of graphene, the quick O-2 adsorption on doped pyridinic nitrogen endow the NCDs-NG composites with enhanced ORR catalytic performance in alkaline electrolyte. The onset potential of -95 mV and kinetic current density of 12.7 mA cm(-2) at -0.7 V (vs. Ag/AgCl) can be compared to those of the commercial 20 wt% Pt/C catalyst. The electron transfer number is about 3.9, revealing a four-electron pathway for ORR. The optimal NCDs-NG catalyst shows superior durability and methanol tolerance than 20 wt% Pt/C. This work demonstrates a feasible and effective strategy to prepare metal-free efficient ORR electrocatalysts for fuel cell applications. (C) 2017 Elsevier B.V. All rights reserved.