摘要
采用第一性原理密度泛函理论结合周期性平板模型模拟研究了Pt_4团簇吸附单层石墨相氮化碳(g-C_3N_4)的几何结构和电子性质,以及氧气在其表面上的吸附行为。同时,对比分析了氧气在纯净的石墨相氮化碳和Pt_4团簇上的吸附行为。计算结果表明,Pt_4团簇吸附在3-s-三嗪环石墨相氮化碳表面,并与四个边缘氮原子成键,形成两个六元环时为最稳定构型。Pt_4团簇倾向于吸附在三嗪环石墨相氮化碳的空位并与邻近三个氮原子成键。由于Pt与N原子较强的杂化作用,以及金属与底物之间较多电子转移增强了Pt_4团簇吸附g-C_3N_4的稳定性。另外,对比分析了氧气在纯净的g-C_3N_4和金属吸附的g-C_3N_4上吸附行为,发现金属原子的加入促进了电子转移,同时拉长了O―O键长。Pt_4吸附3-s-三嗪环g-C_3N_4比Pt_4吸附三嗪环g-C_3N_4表现出微弱的优势,表现出明显的基底扭曲以及较大的吸附能。这些结果表明,化学吸附通过调节电子结构和表面性质增强催化性能的较好方法。
The structural and electronic properties of Pt4 nanoparticles adsorbed on monolayer graphitic carbon nitride（Pt4/g-C3N4）, as well as the adsorption behavior of oxygen molecules on the Pt4/g-C3N4 surface have been investigated through first-principles density-functional theory（DFT） calculations with the generalized gradient approximation（GGA）. The interaction of the oxygen molecules with the bare g-C3N4 and the Pt4 clusters was also calculated for comparison. Our calculations show that Pt nanoparticles prefer to bond with four edge N atoms on heptazine phase g-C3N4（HGCN） surfaces, forming two hexagonal rings. For s-triazine phase g-C3N4（TGCN） surfaces, Pt nanoparticles prefer to sit atop the single vacancy site, forming three bonds with the nearest nitrogen atoms. Stronger hybridization of the Pt nanoparticles with the sp-2 dangling bonds of neighboring nitrogenatoms leads to the Pt4 clusters strongly binding on both types of g-C3N4 surface. In addition, the results from Mulliken charge population analyses suggest that there are electrons flowing from the Pt clusters to g-C3N4.According to the comparative analyses of the O2 adsorbed on the Pt4/HGCN, Pt4/TGCN, and pure g- C3N4 systems, the presence of metal clusters promotes greater electron transfer to oxygen molecules and elongates the O―O bond. Meanwhile, its greater adsorbate-substrate distortion and large adsorption energy render the Pt4/HGCN system slightly superior to the Pt4/TGCN system in catalytic performance. The results validate that being supported on g-C3N4 may be a good way to modify the electronic structure of materials and their surface properties improve their catalytic performance.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2016年第5期1183-1190,共8页
Acta Physico-Chimica Sinica
基金
supported by the National Natural Science Foundation of China(21203227,51574090)~~
关键词
石墨相氮化碳
铂簇
氧气分子
吸附
光催化剂
密度泛函理论
Graphitic carbon nitride
Pt cluster
Oxygen molecule
Adsorption
Photocatalyst
Density functional theory
