Long range corrected-wPBE based analysis of the H2O adsorption on magnetic BC3 nanosheets

摘要

Density functional theory based methods were used for the analysis of the interaction between BC3 (a graphene nanosheet doped with boron), pristine and with point defects (vacancies of carbon - V-C and boron - V-B), and the H2O molecule. The Perdew-Burke-Ernzerhof (LC-wPBE) functional, which includes long range corrections, combined with the 6-31G(d) basis sets developed by Pople et al. was used. The results from the structural and electronic relaxation indicate that the BC3 nanosheets, pristine and with V-C and V-B defects, present magnetic properties. For the neutral case, they have magnetic moments of 2, 4, and 3 bohr magnetons (mu(B)). Roughly, BC3 and BC3/V-B present metallic character but BC3/V-C exhibits semiconductor behavior. Adsorption of the H2O molecule on the pristine BC3 and BC3/V-C nanolayers is mainly governed by van der Waals forces, yielding adsorption energies of -0.45 and -0.21 eV, respectively. In the BC3-H2O and BC3/V-B-H2O systems, the water molecule is oriented in a parallel manner to the BC3 mesh, presenting equilibrium distances of 1.79 and 2.45 angstrom, respectively. This type of functionalization may produce changes in the hybridization of such bi-dimensional structures. Remarkably, in the BC3/V-C-H2O system, the water molecule is dissociated into hydroxyl and hydrogen moieties. Structural stability is achieved in the three systems (as was confirmed by vibrational analysis) and the magnetic properties are also preserved, or even enhanced. On BC3-H2O (pristine, and with V-C and V-B vacancies), the following was found: an increase in the polarity, low chemical reactivity and low values for the work function. Thus, BC3-H2O, BC3/V-C-H2O and BC3/V-B-H2O may be used for the transportation of pharmaceuticals, in optoelectronics and in the design of magnetic devices.