Understanding bond formation and its impact on the capacitive properties of SiW12 polyoxometalates adsorbed on functionalized carbon nanotubes

摘要

Recently, a large number of studies at the experimental level in electrochemical systems for energy storage devices have been performed. However, theoretical approaches are highly desirable to understand the physicochemical properties giving rise to energy storage phenomena. This work was intended to provide insights into the in silico design of novel nanocomposite materials formed by the Keggin polyoxometalate SiW12 anchored to an organic functional group phi - X (where phi corresponds to the phenyl group and X = NH2, OH, COH and COOH) linked to a carbon nanotube. In these systems, the Density of States around the Fermi level is enhanced, giving the composite material the capacity of facile electron transport that may be determinant at the charge/discharge cycling performed in energy storage devices. Charge transfer at the composite materials under study is greatest for the phi - COOH functional group, yielding an enhanced attraction similar to a covalent-type bonding with the SiW12 cluster. The rest of the functional groups induce weak interactions, mediated by van der Waals attractions. Our proposed methodology may represent a tool to develop novel electrode materials based on the composite, that may improve the performance on energy storage devices, such as supercapacitors or Li-ion batteries. (c) 2018 Elsevier Ltd. All rights reserved.