Nitrogen‐Doped Nanoporous Carbon/Graphene Nano‐Sandwiches: Synthesis and Application for Efficient Oxygen Reduction
Nitrogen‐Doped Nanoporous Carbon/Graphene Nano‐Sandwiches: Synthesis and Application for Efficient Oxygen Reduction
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DOI：
10.1002/adfm.201502311
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发表时间：
2015-09
影响因子：
19
通讯作者：
Jing Wei;Yaoxin Hu;Yan-Yu Liang;Biao Kong;Jin Zhang;Jingchao Song;Q. Bao;G. P. Simon;S. Jiang-S.
中科院分区：
文献类型：
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作者：
Jing Wei;Yaoxin Hu;Yan-Yu Liang;Biao Kong;Jin Zhang;Jingchao Song;Q. Bao;G. P. Simon;S. Jiang-S.
提出了一种沸石-咪唑酸盐框架（ZIF）纳米晶体层保护的碳化路线，以制备N掺杂纳米多孔碳/石墨烯纳米三明治。通过均匀成核、均匀沉积和受限生长工艺制备了具有超小ZIF纳米晶体（≈20 nm）完全覆盖氧化石墨烯（GO）的ZIF/氧化石墨烯/ZIF三明治状结构。在氧化石墨烯层上均匀涂覆的ZIF纳米晶可以有效抑制氧化石墨烯在800℃高温处理过程中的团聚。经过碳化和酸蚀，形成了N掺杂的纳米多孔碳/石墨烯纳米片，具有高比表面积（1170 m2 g−1）。这些N掺杂的纳米多孔碳/石墨烯纳米片被用作氧还原的非贵金属电催化剂，并表现出高起始电位（0.92 V vs可逆氢电极；RHE）和大极限电流密度（0.60 V时5.2 mA cm - 2）。为了进一步提高氧还原性能，我们还以硝酸钴和硝酸锌为金属源制备了纳米多孔Co - Nx/碳纳米片，其起始电位（0.96 V）高于商用Pt/C （0.94 V）和N掺杂纳米多孔碳/石墨烯纳米片。这种纳米多孔Co - Nx/碳纳米片在酸性介质中也表现出高活性、稳定性和耐甲醇性等良好性能。
A zeolitic‐imidazolate‐framework (ZIF) nanocrystal layer‐protected carbonization route is developed to prepare N‐doped nanoporous carbon/graphene nano‐sandwiches. The ZIF/graphene oxide/ZIF sandwich‐like structure with ultrasmall ZIF nanocrystals (i.e., ≈20 nm) fully covering the graphene oxide (GO) is prepared via a homogenous nucleation followed by a uniform deposition and confined growth process. The uniform coating of ZIF nanocrystals on the GO layer can effectively inhibit the agglomeration of GO during high‐temperature treatment (800 °C). After carbonization and acid etching, N‐doped nanoporous carbon/graphene nanosheets are formed, with a high specific surface area (1170 m2 g−1). These N‐doped nanoporous carbon/graphene nanosheets are used as the nonprecious metal electrocatalysts for oxygen reduction and exhibit a high onset potential (0.92 V vs reversible hydrogen electrode; RHE) and a large limiting current density (5.2 mA cm−2 at 0.60 V). To further increase the oxygen reduction performance, nanoporous Co‐Nx/carbon nanosheets are also prepared by using cobalt nitrate and zinc nitrate as cometal sources, which reveal higher onset potential (0.96 V) than both commercial Pt/C (0.94 V) and N‐doped nanoporous carbon/graphene nanosheets. Such nanoporous Co‐Nx/carbon nanosheets also exhibit good performance such as high activity, stability, and methanol tolerance in acidic media.