Functionalization of silicene and silicane with benzaldehyde.

Organic functionalization of nanomaterials offers exceptional flexibility in materials design, and applications in molecular sensors and molecular electronics are expected. However, more studies should be conducted to understand the interaction between nanomaterials and organic molecules. In this work, we studied the functionalization of silicene and silicane with benzaldehyde, performing nudged elastic band calculations within density functional theory. We calculated the structural changes of the adsorption process, electronic properties of the main states, and the energetics. In silicene, the adsorption of benzaldehyde on the top site was found to be the most stable, with an adsorption energy of -0.55 eV. For silicane, the functionalization proceeds through a self-propagating reaction on a highly reactive dangling bond generated by a hydrogen atom vacancy. Benzaldehyde adsorbed on this site depicts an adsorption energy of -1.39 eV, which is larger than in bare silicene. Upon attaching, the double C=O bond breaks down turning the molecule into a highly reactive radical, which in this case, abstracts a neighboring H atom of the sheet. This process is highly achievable since the energy barrier to abstract the H atoms is 0.81 eV, whereas the one needed to desorb the molecule is 1.39 eV. After H abstraction, a new dangling bond is generated at the substrate, making a chain reaction possible to potentially form benzaldehyde monolayers. Organic functionalization is an excellent tool to engineer properties of 2D systems, and having a deeper understanding of the adsorption processes is the first step toward the development of new generation devices. Graphical abstract Benzaldehyde adsorbed on silicene and silicane.