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

Abstract

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 CeO₂. Herein, in order to search for non-noble COOR catalysts that are more active than CeO₂, 18 oxygen-functionalized MBenes with orthorhombic and hexagonal crystal structures, denoted as orth-M₂B₂O₂ and hex-M₂B₂O₂ (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-Mo₂B₂O₂, orth-Mo₂B₂O₂, hex-V₂B₂O₂ and hex-Cr₂B₂O₂ were found to be more active than CeO₂ and possess structural stability below 1000 K, showing the potential to replace CeO₂ as the substrates of COOR catalysts. Moreover, orth-Mo₂B₂O₂, hex-V₂B₂O₂ and hex-Cr₂B₂O₂ exhibit even higher COOR catalytic activity than Pt–CeO₂ and Au–CeO₂, 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.