Del Rosso Tommaso, Shtepliuk Ivan, Zaman Quaid, Baldeón Huanqui Luis Gonzalo, Freire Fernando Lazaro, Nascimento Barbosa Andre, Maia da Costa Marcelo Eduardo Huguenin, Aucélio Ricardo Q, Miranda Andrades Jarol Ramon, Mendoza Cesar D, Khan Rajwali, Margheri Giancarlo
Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rua Marques de São Vicente, 22451-900, Rio de Janeiro, Brazil.
Semiconductor Materials Division, Department of Physics, Chemistry and Biology - IFM, Linköping University, S-58183 Linköping, Sweden.
Langmuir. 2024 Sep 13;40(38):20204-18. doi: 10.1021/acs.langmuir.4c02568.
Minimum energy configurations in 2D material-based heterostructures can enable interactions with external chemical species that are not observable for their monolithic counterparts. Density functional theory (DFT) calculations reveal that the binding energy of divalent toxic metal ions of Cd, Pb, and Hg on graphene-gold heterointerfaces is negative, in contrast to the positive value associated with free-standing graphene. The theoretical predictions are confirmed experimentally by Surface Plasmon Resonance (SPR) spectroscopy, where a strong binding affinity is measured for all the heavy metal ions in water. The results indicate the formation of a film of heavy metal ions on the graphene-gold (Gr/Au) heterointerfaces, where the adsorption of the ions follows a Langmuir isotherm model. The highest thermodynamic affinity constant = 3.1 × 10 L mol is observed for Hg@Gr/Au heterostructures, compared to 1.1 × 10 L mol and 8.5 × 10 L mol for Pb@Gr/Au and Cd@Gr/Au, respectively. In the case of Hg ions, it was observed a sensitivity of about 0.01°/ppb and a detection limit of 0.7 ppb (∼3 nmol L). The combined X-ray photoelectron spectroscopy (XPS) and SPR analysis suggests a permanent interaction of all of the HMIs with the Gr/Au heterointerfaces. The correlation between the theoretical and experimental results indicates that the electron transfer from the graphene-gold heterostructures to the heavy metal ions is the key for correct interpretation of the enhanced sensitivity of the SPR sensors in water.
基于二维材料的异质结构中的最低能量构型能够实现与外部化学物质的相互作用，而这些相互作用在其单片对应物中是无法观察到的。密度泛函理论（DFT）计算表明，与独立石墨烯相关的正值相反，镉、铅和汞等二价有毒金属离子在石墨烯-金异质界面上的结合能为负。表面等离子体共振（SPR）光谱实验证实了理论预测，该实验测量了水中所有重金属离子的强结合亲和力。结果表明在石墨烯-金（Gr/Au）异质界面上形成了重金属离子膜，其中离子的吸附遵循朗缪尔等温线模型。Hg@Gr/Au异质结构的热力学亲和常数最高，为3.1×10 L mol，而Pb@Gr/Au和Cd@Gr/Au的分别为1.1×10 L mol和8.5×10 L mol。对于汞离子而言，观察到灵敏度约为0.01°/ppb，检测限为0.7 ppb（约3 nmol L）。结合X射线光电子能谱（XPS）和SPR分析表明所有重金属离子与Gr/Au异质界面存在永久相互作用。理论与实验结果之间的相关性表明，从石墨烯-金异质结构到重金属离子的电子转移是正确解释SPR传感器在水中增强灵敏度的关键。
