Covalent Hybrid of Spinel Manganese-Cobalt Oxide and Graphene as Advanced Oxygen Reduction Electrocatalysts
Covalent Hybrid of Spinel Manganese-Cobalt Oxide and Graphene as Advanced Oxygen Reduction Electrocatalysts
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DOI：
10.1021/ja210924t
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发表时间：
2012-02-22
影响因子：
15
通讯作者：
Dai, Hongjie
中科院分区：
文献类型：
--
作者：
Liang, Yongye;Wang, Hailiang;Dai, Hongjie
通过在氮掺杂、还原氧化石墨烯片上直接纳米颗粒成核和生长以及尖晶石 Co3O4 纳米颗粒的阳离子取代，开发了一种锰钴尖晶石 MnCo2O4/石墨烯杂化物，作为碱性条件下氧还原反应 (ORR) 的高效电催化剂。电化学和X射线近边结构（XANES）研究表明，形成无机纳米碳杂化物的成核和生长方法导致尖晶石氧化物纳米颗粒和氮掺杂还原氧化石墨烯（N-rmGO）片之间发生共价偶联。碳K-边和氮K-边XANES在N-rmGO片中显示出强烈扰动的C-O和C-N键，表明N掺杂石墨烯氧化物和尖晶石氧化物纳米颗粒之间形成了C-O-金属和C-N-金属键。 Co L-edge 和 Mn L-edge XANES 表明用 Mn3+ 取代 Co3+ 位点，这增加了杂化材料中催化位点的活性，与纯氧化钴杂化物相比，进一步提高了 ORR 活性。与纳米颗粒和碳材料（包括 N-rmGO）的物理混合物相比，共价键合杂化物具有更高的活性和耐用性。在相同的质量负载下，MnCo2O4/N-石墨烯杂化物在中等过电势下的ORR电流密度优于Pt/C，并且在碱性溶液中的稳定性优于Pt/C。
Through direct nanoparticle nucleation and growth on nitrogen doped, reduced graphene oxide sheets and cation substitution of spinel Co3O4 nanoparticles, a manganese-cobalt spinel MnCo2O4/graphene hybrid was developed as a highly efficient electrocatalyst for oxygen reduction reaction (ORR) in alkaline conditions. Electrochemical and X-ray near-edge structure (XANES) investigations revealed that the nucleation and growth method for forming inorganic-nanocarbon hybrids results in covalent coupling between spinel oxide nanoparticles and N-doped reduced graphene oxide (N-rmGO) sheets. Carbon K-edge and nitrogen K-edge XANES showed strongly perturbed C-O and C-N bonding in the N-rmGO sheet, suggesting the formation of C-O-metal and C-N-metal bonds between N-doped graphene oxide and spinel oxide nanoparticles. Co L-edge and Mn L-edge XANES suggested substitution of Co3+ sites by Mn3+, which increased the activity of the catalytic sites in the hybrid materials, further boosting the ORR activity compared with the pure cobalt oxide hybrid. The covalently bonded hybrid afforded much greater activity and durability than the physical mixture of nanoparticles and carbon materials including N-rmGO. At the same mass loading, the MnCo2O4/N-graphene hybrid can outperform Pt/C in ORR current density at medium overpotentials with stability superior to Pt/C in alkaline solutions.