The binding properties of single noble metal atoms (Pd, Pt and Ir) anchored Janus MoSSe monolayers (MLs), the catalytic activity of Pd- and Pt-MoSSe in oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as well as the adsorption behaviors of Ir-MoSSe for harmful NO, CO and NH3 molecules are systematically studied from the first-principles calculations. Current results reflect the ascending order (Pd-MoSSe < Pt-MoSSe < Ir-MoSSe) of stability and binding strength as well as the tunable electronic properties of Janus MoSSe ML by anchoring single Pd, Pt and Ir atoms. Pd- and Pt-MoSSe exhibit excellent bifunctional catalytic performance, especially the former having lower overpotentials 0.43 and 0.50 V for ORR and OER, which are better than the well-known Pt (1 1 1) (0.45 V) and IrO2 (0.56 V) electrocatalysts, respectively. The adsorption nature for NO, CO and NH3 molecules changes from physisorption (on pristine MoSSe) to chemisorption (on Ir-MoSSe), especially for NO and CO molecules due to their ultra-low adsorption energies (-3.72 and -2.91 eV, respectively). Thus, Pd- and Pt-MoSSe (particularly the former) may act as promising highly-efficient ORR/OER bifunctional electrocatalysts, and Ir-MoSSe may serve as a potential sensitive harmful gas detector for NO and CO molecules. (C) 2022 Elsevier Inc. All rights reserved.
