Electrocatalytic CO Reduction Empowered by 2D Hexagonal Transition Metal Borides.

Electrocatalysis holds immense promise for producing high-value chemicals and fuels through the carbon dioxide reduction reaction (CORR), advancing global sustainability and carbon neutrality. However, conventional electrocatalysts based on transition metals are often limited by significant overpotentials. Since the discovery of the first hexagonal MAB (h-MAB) phase, TiInB, and its 2D derivative in 2019, 2D hexagonal transition metal borides (h-MBenes) have emerged as promising candidates for various electrochemical applications. This study presents the first theoretical investigation into the CORR catalytic properties of pristine h-MBenes (h-MB) and their ─O (h-MBO) and ─OH (h-MBOH) terminated counterparts, focusing on metals such as Sc, Ti, V, Zr, Nb, Hf, and Ta. These results reveal while h-MB and h-MBO exhibit poor catalytic performance due to overly strong or weak interactions with CO, h-MBOH shows great promise. Notably, ScBOH, TiBOH, and ZrBOH display exceptionally low limiting potentials (U) of -0.46, -0.53, and -0.64 V, respectively. These findings uncover the unique role of ─OH in tuning the electronic properties of h-MBenes, thereby optimizing intermediate adsorption, which prevents excessive binding and enhances catalytic efficiency. This research offers valuable insights into the potential of h-MBenes as highly efficient CORR catalysts, underscoring their versatility and significant prospects for electrochemical applications.