Computational exploration of borophane-supported single transition metal atoms as potential oxygen reduction and evolution electrocatalysts†
Abstract
Novel monolayer-boron (borophene) is a recent addition to the family of 2D materials. In particular, full surface hydrogenation of triangular borophene (borophane (BH)) to passivate empty p orbitals in boron is identified as producing a new stable 2D material that possesses direction-dependent Dirac cones similar to graphene. By a series of density functional theory (DFT) computations, we investigated the potential of single transition metal atoms supported on borophane with vacancies (the TM–BH system) as an efficient ORR/OER electrocatalyst for applications in renewable energy technologies. In TM–BH systems, the coupling of d-orbitals of the TM dopant with the p-orbitals of surrounding boron atoms results in an increase in the density of states near the Fermi-level generating active sites to facilitate the ORR/OER via an efficient four-electron transfer mechanism. Among the considered TM–BH systems, Fe–BH and Rh–BH were found to be promising ORR electrocatalysts with overpotentials (ηORR) of 0.43 V and 0.47 V, respectively, whereas, for the OER, Rh–BH with 0.24 V has the smallest ηOER value followed by Co–BH (0.37 V), under the equilibrium electrode potential. These ηORR and ηOER values indicate higher activities than the current most active ORR (Pt(111) (0.63 V)) and OER (rutile-type RuO2 (0.37 V)) electrocatalysts.