Hydrogen spillover and storage for single-site metal catalysts, including single-atom catalysts (SACs) and single nanocluster catalysts, have been elucidated for various supports but remain poorly understood for inert carbon supports. Here, we use synchrotron-radiation-based methods to investigate the role of single-site Ti catalysts on graphene for hydrogen spillover and storage. Our in situ angle-resolved photoemission spectra results demonstrate a band gap opening, and X-ray absorption spectra reveal the formation of C–H bonds, both indicating partial graphene hydrogenation. With increasing Ti deposition and H₂ exposure, the Ti atoms tend to aggregate to form nanocluster catalysts and yield 13.5% sp³-hybridized carbon atoms corresponding to a hydrogen-storage capacity of 1.11 wt % (excluding the weight of the Ti nanoclusters [Bhowmick, R. et al. J. Am. Chem. Soc.2011, 133 (14), 5580]). Our results demonstrate how a simple spillover process at Ti SACs can lead to covalent hydrogen bonding on graphene, thereby providing a strategy for the rational design of carbon-supported single-site catalysts.

中文翻译：

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单中心钛催化剂在石墨烯上的氢溢出和储存

单中心金属催化剂（包括单原子催化剂 (SAC) 和单纳米簇催化剂）的氢溢出和储存已被阐明用于各种载体，但对于惰性碳载体仍知之甚少。在这里，我们使用基于同步辐射的方法来研究单中心 Ti 催化剂在石墨烯上的氢溢出和储存作用。我们的原位角分辨光电子能谱结果表明带隙开口，X 射线吸收光谱显示 C-H 键的形成，均表明石墨烯部分氢化。随着 Ti 沉积和 H ₂暴露的增加，Ti 原子倾向于聚集形成纳米簇催化剂并产生 13.5% sp ³-杂化碳原子对应于 1.11 wt% 的储氢容量（不包括 Ti 纳米团簇的重量 [Bhowmick, R. et al. J. Am. Chem. Soc. 2011 , 133 (14), 5580]）。我们的研究结果证明了 Ti SAC 的简单溢出过程如何导致石墨烯上的共价氢键合，从而为碳负载单中心催化剂的合理设计提供了策略。