Theoretical regulating the M-site composition of Janus MXenes enables the tailoring design for highly active bifunctional ORR/OER catalysts

Rechargeable metal-air batteries generally require efficient, durable, and safe bifunctional electrocatalysts to simultaneously support oxygen reduction/evolution reactions (ORR/OER). Herein, we employed first-principles calculations to explore the structure-activity relationship between the composition control of metal atoms and the catalytic activity of Pt-doped Ti2–xMnxCO2 single-atom catalysts (SACs). The research found a clear linear relationship between the proportion of Mn and bifunctional performance, which can effectively modulate catalytic activity. Additionally, it shows excellent bifunctional catalytic activity at medium concentrations, among which the catalyst of Pt-VO-Ti0.89Mn1.11CO2 displays the lowest overpotential (ηORR/OER = 0.26/0.28 V). Attributed to the modulation of the average magnetism of Mn and the d-band center of Pt by different components, the bonding strength of the active center of Pt to adsorption intermediates is changed, resulting in the enhancement of the catalyst activity. Crucially, the molecular orbital-level bonding between the active site Pt and the adsorbed intermediate OH is clarified, shedding light on the involvement of the partially occupied antibonding state of Pt's d orbital in the activation process. The research extensively explores the control of catalyst activity through composition, offering strong support for designing and optimizing highly active Janus MXene-supported SACs.