New horizons of MBenes: highly active catalysts for the CO oxidation reaction.

The search for materials with high intrinsic carbon monoxide oxidation reaction (COOR) catalytic activity is critical for enhancing the efficiency of reducing CO contamination. COOR catalysts, however, have long relied heavily on noble metals and CeO 2 . Herein, in order to search for non-noble COOR catalysts that are more active than CeO 2 , 18 oxygen-functionalized MBenes with orthorhombic and hexagonal crystal structures, denoted as orth-M 2 B 2 O 2 and hex-M 2 B 2 O 2 (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W), were investigated in terms of their COOR catalytic activity by high-throughput first-principles calculations. Hex-Mo 2 B 2 O 2 , orth-Mo 2 B 2 O 2 , hex-V 2 B 2 O 2 and hex-Cr 2 B 2 O 2 were found to be more active than CeO 2 and possess structural stability below 1000 K, showing the potential to replace CeO 2 as the substrates of COOR catalysts. Moreover, orth-Mo 2 B 2 O 2 , hex-V 2 B 2 O 2 and hex-Cr 2 B 2 O 2 exhibit even higher COOR catalytic activity than Pt-CeO 2 and Au-CeO 2 , and are expected to be applied as COOR catalysts directly. Further investigations showed that the formation energy of oxygen vacancies could be used as the descriptor of COOR catalytic activity, which would help to reduce the amount of calculations significantly during the catalyst screening process. This work not only reports a series of 2D materials with high COOR catalytic activity and opens up a new application area for MBenes, but also provides a reliable strategy for highly efficient screening for COOR catalysts.