Template growth of nitrogen-doped mesoporous graphene on metal oxides and its use as a metal-free bifunctional electrocatalyst for oxygen reduction and evolution reactions
Template growth of nitrogen-doped mesoporous graphene on metal oxides and its use as a metal-free bifunctional electrocatalyst for oxygen reduction and evolution reactions
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DOI：
10.1016/j.cattod.2017.02.012
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发表时间：
2018-03
期刊：
影响因子：
5.3
通讯作者：
Hao-Fan Wang;Cheng Tang;Qiang Zhang
中科院分区：
文献类型：
--
作者：
Hao-Fan Wang;Cheng Tang;Qiang Zhang
无金属电催化剂是一种新兴能源材料，可替代贵金属在电化学能量转换装置中进行有效的氧还原反应（ORR）和析氧反应（OER）。强烈考虑开发一种具有丰富的高活性位点和完全暴露于反应物的有效双功能催化剂。本文提出了一种氮掺杂介孔石墨烯骨架（NMGF），其具有固有的N/O杂原子和丰富的拓扑缺陷，用于无金属ORR/OER。 NMGF 是通过在 MgO 模板上直接化学气相沉积制备的。所得 NMGF 具有高孔隙率、1440 m2g−1 的大比表面积以及 57.0 S cm−1 的高电导率。这种独特的结构被证明具有多种优点，包括由于缺陷和杂原子而产生的丰富的活性中心、通过非常高的电化学活性表面积和亲水表面提高利用效率、促进离子通过互连孔扩散以及在高导电性3D框架中平滑的电子传输，从而产生优异的ORR和OER双功能活性。 ORR半波电位为0.714 V，达到10.0 mA cm−2OER电流密度的电位为1.664 V，电位差为0.95 V。这种双功能性能优于用于氧氧化还原反应的常规贵金属基催化剂（例如Pt/C和IrO2）。
Metal-free electrocatalyst is an emerging energy material to replace precious metal for effective oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in a working electrochemical energy conversion device. Developing an effective bifunctional catalyst with abundant highly active sites and full exposure to reactants is strongly considered. Herein a nitrogen-doped mesoporous graphene framework (NMGF) was proposed with intrinsic N/O heteroatoms and abundant topological defects for metal-free ORR/OER. The NMGF was fabricated by direct chemical vapor deposition on MgO template. The as-obtained NMGF exhibited high porosity with a large specific surface area of 1440 m2g−1as well as a high electrical conductivity of 57.0 S cm−1. This unique structure is demonstrated to possess several advantages, including plentiful active centers due to defects and heteroatoms, improved utilization efficiency by very high electrochemically active surface area and hydrophilic surface, facilitated ion diffusion through interconnected pores and smooth electron transportation in the highly conductive 3D framework, thereby leading to superior ORR and OER bifunctional activity. The ORR half-wave potential was 0.714 V, and the potential to reach 10.0 mA cm−2OER current density was 1.664 V with the potential gap of 0.95 V. This bifunctional performance was better than routine precious metal-based catalysts (e.g.Pt/C and IrO2) for oxygen redox reaction.