Nitrogen-Doped Graphene Oxide Electrocatalysts for the Oxygen Reduction Reaction
Nitrogen-Doped Graphene Oxide Electrocatalysts for the Oxygen Reduction Reaction
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DOI：
10.1021/acsanm.8b02235
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发表时间：
2019-03-01
影响因子：
5.9
通讯作者：
Gupta, Gautam
中科院分区：
文献类型：
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作者：
Dumont, Joseph H.;Martinez, Ulises;Gupta, Gautam
用于氧还原反应 (ORR) 的无铂族金属（不含 PGM）电催化剂通常表现出复杂的功能化石墨结构。由于这种复杂的结构，人们对高性能材料合成的设计因素的了解有限。石墨烯是碳的二维六边形结构，易于结构和官能团修饰，使其成为研究用作电催化剂的更复杂石墨材料的关键特性的理想类似物。在本文中，我们报道了用于 ORR 的活性氮掺杂氧化石墨烯催化剂的合成，其中通过简单的溶剂和电化学处理增强了其活性和四电子选择性。根据汉森的溶解度参数选择的溶剂，通过以下方式驱动功能化石墨烯材料的形态发生重大变化：(i) 在石墨片中形成微孔，导致边缘缺陷；(ii) 在石墨片中诱导 3D 结构，促进 ORR。此外，这些催化剂的循环突出了活性位点的多样性，具有不同的耐久性，随着时间的推移，形成高度选择性的催化剂，性能损失最小。在碱性电解质中表现出高 ORR 活性，相对于 RHE，起始电位约为 1.1 V，半波电位为 0.84 V。此外，长期稳定性电位循环显示半波电位损失最小（
Platinum group metal-free (PGM-free) electrocatalysts for the oxygen reduction reaction (ORR) often exhibit a complex functionalized graphitic structure. Because of this complex structure, limited understanding exists about the design factors for the synthesis of high-performing materials. Graphene, a two-dimensional hexagonal structure of carbon, is amenable to structural and functional group modifications, making it an ideal analogue to study crucial properties of more complex graphitic materials utilized as electrocatalysts. In this paper, we report the synthesis of active nitrogen-doped graphene oxide catalysts for the ORR in which their activity and four-electron selectivity are enhanced using simple solvent and electrochemical treatments. The solvents, chosen based on Hansen's solubility parameters, drive a substantial change in the morphology of the functionalized graphene materials by (i) forming microporous holes in the graphitic sheets that lead to edge defects and (ii) inducing 3D structure in the graphitic sheets that promotes ORR Additionally, the cycling of these catalysts has highlighted the multiplicity of the active sites, with different durability, leading to a highly selective catalyst over time, with a minimal loss in performance. High ORR activity was demonstrated in an alkaline electrolyte with an onset potential of similar to 1.1 V and half-wave potential of 0.84 V vs RHE. Furthermore, long-term stability potential cycling showed minimal loss in half-wave potential (