In situ trapped high-density single metal atoms within graphene: Iron-containing hybrids as representatives for efficient oxygen reduction
In situ trapped high-density single metal atoms within graphene: Iron-containing hybrids as representatives for efficient oxygen reduction
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石墨烯内原位捕获的高密度单金属原子：含铁杂化物作为高效氧还原的代表
DOI：
10.1007/s12274-017-1840-8
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发表时间：
2018-04-01
期刊：
影响因子：
9.9
通讯作者：
Song, Li
中科院分区：
文献类型：
--
作者：
Liu, Daobin;Wu, Chuanqiang;Song, Li
原子分散型催化剂因其对特定催化反应的效率和化学选择性上级传统催化剂而在能源转化应用中受到关注。然而，由于载体上的金属负载含量极低，难以精确控制金属位置和量以及高温下的低稳定性，它们具有局限性。我们通过葡萄糖、双氰胺和无机金属盐的一步热解制备了高掺杂的单金属原子杂化物。高角度环形暗场扫描透射电子显微镜（HAADF-STEM）和X射线吸收精细结构光谱（XAFS）显示，氮原子掺杂到石墨烯基质中是通过产生金属-Nx配位结构来稳定金属原子的关键。由于石墨烯基质的强锚定作用，金属负载含量超过4 wt.%在孤立的原子杂化物中（Pt含量高达9.26wt.%在Pt掺杂的混合物中）。此外，单一的铁掺杂的杂化物（Fe@ N掺杂的石墨烯）对氧还原反应表现出显著的电催化性能。在310 mA·cm-2的电流密度下，峰值功率密度为199 mW·cm-2，并且当其用作组装的锌-空气电池中的阴极催化剂时，其优于商业Pt/C催化剂的峰值功率密度上级。该工作为设计和制备高掺杂单金属原子（SMAs）催化剂提供了一种可行的方法。
Atomically dispersed catalysts have attracted attention in energy conversion applications because their efficiency and chemoselectivity for special catalysis are superior to those of traditional catalysts. However, they have limitations owing to the extremely low metal-loading content on supports, difficulty in the precise control of the metal location and amount as well as low stability at high temperatures. We prepared a highly doped single metal atom hybrid via a single-step thermal pyrolysis of glucose, dicyandiamide, and inorganic metal salts. High-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption fine structure spectroscopy (XAFS) revealed that nitrogen atoms doped into the graphene matrix were pivotal for metal atom stabilization by generating a metal-Nx coordination structure. Due to the strong anchoring effect of the graphene matrix, the metal loading content was over 4 wt.% in the isolated atomic hybrid (the Pt content was as high as 9.26 wt.% in the Pt-doped hybrid). Furthermore, the single iron-doped hybrid (Fe@N-doped graphene) showed a remarkable electrocatalytic performance for the oxygen reduction reaction. The peak power density was ∼199 mW·cm−2 at a current density of 310 mA·cm−2 and superior to that of a commercial Pt/C catalyst when it was used as a cathode catalyst in assembled zinc-air batteries. This work offered a feasible approach to design and fabricate highly doped single metal atoms (SMAs) catalysts for potential energy applications.