The adsorption of CN− on B-doped carbon nanotubes: The first-principles study

Abstract

The first-principles method based on density functional theory has been used to investigate the adsorption performance of cyanide ions on intrinsic and B-doped carbon nanotubes (CNTs). We first investigate the effect of B-doping on the reactivity of CNTs. It is found that B-doping enhances the reactivity of CNTs while it ensures the structure of the doped CNTs is stable. Then, we perform a comparative analysis of various indices for each adsorption system. The results show that the adsorption effect of intrinsic CNTs on cyanide ions is weak, and there exists only physical adsorption between them. After B-doping, the adsorption energy between CNTs and cyanide ions increases by 87.6–122.8%, and the adsorption distance decreases substantially. The analysis of the energy band structure, partial density of states (PDOS) and charge density shows that the [Formula: see text]-orbital electrons of both C and N atoms in [Formula: see text] are filled into the [Formula: see text]-hybrid orbital of the B atom and the effective overlap of charges of each adsorption system is greatly increased as well. Therefore, the adsorption effect of B-doped CNTs on cyanide ions is greatly enhanced, and there is chemical adsorption formed between them. In addition, through analyzing the geometric structure and PDOS of each adsorption system, it can be seen that the adsorption effect of B-doped CNTs on the C atom in [Formula: see text] is better than that on the N atom. This study shows that B-doped CNTs can be used as an effective adsorbing or sensing material for [Formula: see text] in wastewater.