Exploring and Elucidating the CO<sub>2</sub> Reduction Mechanisms on the Surface of Two-Dimensional Nitrogen-Vacancy (V<sub>N</sub>) Hexagonal Boron Nitride
Lokesh Yadav, Srimanta Pakhira
Abstract
The conversion of waste carbon dioxide (CO 2 ) gas into valuable products and fuels through an electrocatalytic CO 2 reduction reaction (CO 2 RR) is a promising approach. The sluggish kinetics of the CO 2 RR require the development of novel strategies for the electrocatalyst design. Two-dimensional (2D) materials emerge as promising candidates for the CO 2 RR due to their distinctive electronic and structural properties. This study follows the first-principles–based DFT-D method to examine the electrocatalytic competences of the defective two-dimensional boron nitride monolayer (d-BN) material toward the CO 2 RR. Introducing a particular defect with nitrogen vacancies in 2D single-layer pristine hexagonal boron nitride (V N _d-BN) can efficiently activate the CO 2 molecules for hydrogenation by reducing the electronic band gap of pristine hBN from 6.23 to 3.0 eV. Therefore, the V N _d-BN material can act as a large band gap semiconductor. Our findings demonstrate that the defective regions in 2D monolayer V N _d-BN serve as active sites (boron) for both the adsorption and activation of CO 2 . The subsequent hydrogenation steps occur sequentially once the CO 2 molecule is adsorbed on the catalytic surface. Our results indicate that the OCHO* path is the most favorable for CH 4 production. Hence, the 2D monolayer V N _d-BN material holds a great promise as a cost-effective catalyst for the CO 2 RR, and it presents a viable alternative to expensive platinum (Pt) catalysts.