Single Cr atom supported on boron nitride nanotubes for the reaction of N2O reduction by CO: A density functional theory study

Abstract

The removal of harmful N2O and CO in one step has attracted extensive research interest. Here, we studied the feasibility of N2O + CO reaction on single atom catalysts (SACs) supported on defective boron nitride nanotube (BNNT) by means of density functional theory (DFT) calculations. The Cr single atom catalyst which can avoid catalyst poisoning was screened from five low-price transition metal atoms (Ti, Cr, Mn, Fe, and Co) based on the adsorption strength of reactant and product on catalyst. The stepwise mechanism was considered which reveals the reaction path involves N2O decomposition, CO oxidation and CO2 desorption. The rate-limiting step is CO2 desorption with the desorption barrier of 0.42 eV. Along the reaction path, optimized structures and electronic property analyses indicate Cr atom acts as bridge to transfer electron due to its 3d orbital, which plays an important role in activation of N2O and CO molecules. Meanwhile, BNNT support with high redox stability acts as electron reservoir, withdrawing or donating electron, to facilitate the whole reaction. Therefore, Cr/BNNT is proposed to be a promising and highly efficient catalyst for eliminating environmentally unfriendly N2O and CO gases simultaneously.