Tang Yanan, Dai Xianqi, Yang Zongxian, Pan Lijun, Chen Weiguang, Ma Dongwei, Lu Zhansheng
Department of Physics and Electronic Science, Zhengzhou Normal University, Zhengzhou, Henan 450044, People's Republic of China.
Phys Chem Chem Phys. 2014 May 7;16(17):7887-95. doi: 10.1039/c4cp00149d.
The geometries, stabilities, electronic properties and catalytic capability of the platinum catalyst supported on oxidized graphene (Pt/OG) are investigated using the first-principles density-functional theory. Compared with the oxygen adatom, the hydroxyl molecule adsorbs weakly and aggregates easily on graphene, while the single oxygen adatom will form the epoxy group (EG) on pristine graphene or the oxygen dopant (OD) in defective graphene. The formation of EG and OD are used to model oxidized graphene (OG). The OD at the vacancy site forms the most stable configuration with a small formation energy and large diffusion barrier, indicating that an OD is easier to incorporate into the graphene sheet. The OD sheet as a substrate can effectively enhance the stability of the Pt catalyst as compared with pristine graphene or the graphene sheet with EG. Moreover, the complete CO oxidation reactions on the Pt/OD system include a two-step process with the Langmuir-Hinshelwood (LH) reaction as a starting step followed by the Eley-Rideal (ER) reaction. The results suggest that the OD sheet can be used as the reactive support to control the stability and reactivity of catalysts, which opens up a new avenue for fabrication of low cost and highly efficient graphene-based catalysts.
采用第一性原理密度泛函理论研究了负载在氧化石墨烯（Pt/OG）上的铂催化剂的几何结构、稳定性、电子性质和催化能力。与氧原子相比，羟基分子在石墨烯上吸附较弱且容易聚集，而单个氧原子会在原始石墨烯上形成环氧基团（EG）或在缺陷石墨烯中形成氧掺杂剂（OD）。EG和OD的形成用于模拟氧化石墨烯（OG）。空位处的OD形成最稳定的构型，具有较小的形成能和较大的扩散势垒，表明OD更容易掺入石墨烯片层。与原始石墨烯或具有EG的石墨烯片层相比，OD片层作为基底可以有效地提高Pt催化剂的稳定性。此外，Pt/OD体系上的完全CO氧化反应包括两步过程，第一步是Langmuir-Hinshelwood（LH）反应，随后是Eley-Rideal（ER）反应。结果表明，OD片层可作为活性载体来控制催化剂的稳定性和反应性，这为制备低成本、高效的石墨烯基催化剂开辟了一条新途径。
