CO<sub>2</sub> Hydrogenation with High Selectivity by Single Bi Atoms on MXenes Enabled by a Concerted Mechanism
Kaifeng Niu, Lin Chen, Johanna Rosén, Jonas Björk
Abstract
High Resolution Image Download MS PowerPoint Slide Developing efficient catalysts for the capture and direct conversion of CO 2 into various chemicals is essential to alleviate CO 2 emissions and minimize the negative environmental effects of fossil fuels. Combining density functional theory calculations and microkinetic analysis, we propose that single Bi atoms supported on V 2 CO 2 MXenes (Bi@V 2 CO 2 ) are promising single-atom catalysts (SAC) for CO 2 hydrogenation. The catalytic performance of Bi SACs is ensured by the stable single-atom dispersion of Bi atoms on V 2 CO 2 and enhanced adsorption of CO 2 . Of importance, Bi@V 2 CO 2 exhibits remarkable selectivity toward the synthesis of formic acid (HCOOH), in which the main competing reaction, namely, the reverse water gas shift (RWGS) and the formation of CO, is strictly prohibited. In contrast to conventional Cu or In 2 O 3 catalysts, CO 2 hydrogenation exhibits a unique mechanism on Bi@V 2 CO 2, in which the formic acid is directly generated via a concerted pathway. As a result, the formation of both intermediate HCOO and COOH is prevented, leading to high selectivity (nearly 100%) toward HCOOH on Bi@V 2 CO 2 . Moreover, analysis of the kinetic behavior suggests that the stabilization of HCOOH adsorption would be an effective approach to promote catalyst performance toward methanol synthesis.