Screening effective single-atom ORR and OER electrocatalysts from Pt decorated MXenes by first-principles calculations

Abstract

The ORR and OER properties of a series of recombinant single atom catalysts (SACs) prepared by recombining Pt single atoms on 26 representative MXenes were comprehensively studied by first-principles calculations. The stability of Pt atoms on the MXene surface was studied using formation energies and diffusion energy barriers. Charge transfer analysis showed that the Pt atoms not only acted as the catalytic center of the SACs but also behaved as a charge transfer medium between the MXene substrate and the reactants. The catalytic properties of the recombinant SACs were dependent on several interacting factors including the Pt-5d states, the work functions of the recombinant systems, the electronegativity of the submetals, and the vacant electron orbitals of the C/N and O/F elements of the MXenes. In all the recombinant SACs under investigation, V-, Ti-, Nb-, and Cr-based MXenes, including Ti₂CF₂-V_F-Pt, Ti₃C₂F₂-V_F-Pt, V₂CO₂-V_O-Pt, Nb₂CF₂-V_F-Pt, Nb₄C₃F₂-V_F-Pt, Cr₂TiC₂F₂-V_F-Pt, Ti₃(C,N)₂-CO₂-V_O-Pt, and Ti₃(C,N)₂-NO₂-V_O-Pt, were screened as promising ORR catalysts. In particular, three F-terminated ones (Nb₂CF₂-V_F-Pt, Nb₄C₃F₂-V_F-Pt, and Cr₂TiC₂F₂-V_F-Pt) were proposed as effective ORR/OER bifunctional catalysts. The results revealed the highly active nature of the selected SACs and highlighted the great potential of MXenes as efficient ORR and OER catalysts.