Liquid-to-gas transition derived cobalt-based nitrogen-doped carbon nanosheets with hierarchically porous for oxygen reduction reaction
Liquid-to-gas transition derived cobalt-based nitrogen-doped carbon nanosheets with hierarchically porous for oxygen reduction reaction
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DOI：
10.1016/j.apsusc.2020.145365
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发表时间：
2020-04
影响因子：
6.7
通讯作者：
Zhenlu Zhao;Qiqi Sha;Kongshuo Ma;Yizhong Lu
中科院分区：
文献类型：
--
作者：
Zhenlu Zhao;Qiqi Sha;Kongshuo Ma;Yizhong Lu
本文采用可控分级热解策略制备了Co@ CoOx基三维氮掺杂类石墨烯碳纳米片（3D HPN-GCNS/Co@CoOx），在面内和面外均呈现出三维蓬松、分级多孔的纳米结构，大量Co@ CoOx基纳米颗粒均匀嵌入类石墨烯碳纳米片和介孔活性边缘，引入了更多的ORR活性位点。当应用于ORR时，混合物在0.1 M KOH中表现出0.87 V的半波电位（E1/2）和0.92 V的起始电位（Eonset），与商业20% Pt/C相当。杂化材料表现出更好的甲醇耐受性和稳定性，在5000次循环前后ORR性能几乎没有变化。ORR过程中H2 O2产率小于5%，电子转移数大于3.9。其显著特点主要是协同增强效应，即三维蓬松、分层多孔的面内外纳米结构提供了较大的可及比活性面积，使物种能够有效参与ORR，促进快速传质;富氮掺杂的类石墨烯碳纳米片促进了O2吸附，保证了快速电子传递;大量的基于Co@ CoOx的纳米颗粒引入更多的ORR活性位点。所有优点协同提高ORR效率，使其成为高效ORR催化剂。
Here, Co@CoOx-based three-dimensional nitrogen-doped graphene-like carbon nanosheets (denoted as 3D HPN-GCNS/Co@CoOx) are fabricated by controllable grading-pyrolysis strategy, in which they show 3D fluffy and hierarchically porous nanostructure in and out-of-plane; large numbers of Co@CoOx-based nanoparticles uniformly embedded on graphene-like C nanosheets and mesoporous active edge introduce more ORR active sites. When applied for ORR, hybrids exhibit a half-wave potential (E1/2) of 0.87 V and an onset potential (Eonset) of 0.92 V in 0.1 M KOH, comparable to that of commercial 20% Pt/C. The hybrids display better methanol tolerance and stability, with almost no change of ORR performance before and after 5000 cycles. H2O2yield in ORR process is less than 5% and number of electron transfer is higher than 3.9. The remarkable features are mainly ascribed to synergistic enhancement effect, in which 3D fluffy and hierarchically porous nanostructure in and out-of-plane supplies large accessible specific activity area, allows species to efficiently participate in ORR and facilitates fast mass transfer; graphene-like C nanosheets with N-rich dopant promote O2adsorption and assure fast electron transport; large numbers of Co@CoOx-based nanoparticles introduce more ORR active sites. All the advantages synergistically enhance the ORR efficiency and make it a highly efficient ORR catalyst.