Early stages of surface graphitization on nanodiamond probed by x-ray photoelectron spectroscopy
Early stages of surface graphitization on nanodiamond probed by x-ray photoelectron spectroscopy
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DOI：
10.1103/physrevb.84.233407
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发表时间：
2011-12-19
影响因子：
3.7
通讯作者：
Bergonzo, Philippe
中科院分区：
文献类型：
--
作者：
Petit, Tristan;Arnault, Jean-Charles;Bergonzo, Philippe
我们研究了爆轰纳米金刚石在真空下连续退火处理过程中石墨化的早期阶段，使用X射线光电子能谱。观察到两种不同的温度依赖性制度。低于900摄氏度，纳米金刚石表面重建成石墨域，但不改变金刚石核。高于900摄氏度，石墨化，即，碳杂化从SP（3）变为SP（2），从纳米金刚石表面向金刚石核发生。在纳米金刚石上观察到石墨化的温度比在大块金刚石上低得多，这是由于其表面上的高浓度结构缺陷。这些结果表明，真空低温退火是一种有效的方法，表面和体石墨化解耦。在这些条件下形成的混合纳米碳，由金刚石核和薄的石墨外壳构成，可能具有有趣的催化和化学性质。
We have investigated the early stages of graphitization on detonation nanodiamond during sequential annealing treatments under vacuum using x-ray photoelectron spectroscopy. Two different temperature-dependent regimes were observed. Below 900 degrees C, the nanodiamond surface reconstructs into graphitic domain but does not alter the diamond core. Above 900 degrees C, graphitization, i.e., carbon hybridization changes from sp(3) to sp(2), occurs from the nanodiamond surface toward the diamond core. Graphitization is observed at much lower temperatures on nanodiamonds than on bulk diamond due to the high concentration of structural defects on their surface. These results indicate that low-temperature annealing under vacuum is an efficient method to uncouple surface and bulk graphitization. Hybrid nanocarbons formed in these conditions, constituted of a diamond core with a thin graphitic outer shell, may have interesting catalytic and chemical properties.