论文标题
通过更改吸附模式来调整电子注入机制：αAlizarin在TiO2上的案例研究
Tuning the electron injection mechanism by changing the adsorption mode:the case study of Alizarin on TiO2
论文作者
论文摘要
具有强烈荧光染料的官能化TIO2纳米颗粒是一种有前途的工具，用于多种技术应用，从光化学，光催化，光伏，光动力疗法或生物成像范围不等。在这里，我们通过密度功能理论（DFT）计算，介绍了不同形状的TiO2纳米颗粒（NP）的案例研究。我们发现，根据α和Tio2之间的键数量和类型，αarin可以以三种不同的方式结合：“三叉后”，“ bidented”和“螯合”。接下来，我们通过时间依赖性密度功能理论（TDDFT）计算研究这些系统的光学性质。基于吸收光谱和Kohn-Sham轨道分析，我们发现电子注射机理取决于αarin结合模式与TIO2表面。尽管对于螯合和螯合的吸附模式，观察到了直接电荷转移，对于三方面，间接机制控制了激发后的电荷转移过程。我们的结果与现有的实验数据非常吻合，并表明，通过定制TiO2 NP的形状，因此确定了在表面上普遍暴露的不满意的Ti原子的类型，可以控制主要的注射机制。
Functionalized TiO2 nanoparticles with intense fluorescent dyes is a promising tool for several technological applications ranging from photochemistry, photocatalysis, photovoltaics, photodynamic therapy or bioimaging. Here, we present the case study of the Alizarin adsorption on TiO2 nanoparticles (NPs) of different shape and increasing size up to 2.2 nm (700 atoms), by means of density functional theory (DFT) calculations. We find that Alizarin can bind in three different ways, depending on the number and type of bonds between Alizarin and TiO2: "tridented", "bidented" and "chelated". Next, we investigate the optical properties of these systems by time-dependent density functional theory (TDDFT) calculations. Based on the absorption spectra and the Kohn-Sham orbitals analysis, we discovered that the mechanism of electron injection depends on the Alizarin binding mode to the TiO2 surface. While for bidented and chelated adsorption modes a direct charge transfer is observed, for the tridented one an indirect mechanism governs the charge transfer process following the excitation. Our results are in good agreement with existing experimental data and suggests that by tailoring the shape of the TiO2 NPs and, thus, determining the type of undercoordinated Ti atoms prevalently exposed at the surface, it is possible to control the predominant injection mechanism.
