MnO Decoration on Co(0001): Charge Transfer, Surface Restructuring, and Enhanced CO Dissociation in Fischer–Tropsch Synthesis

Abstract

Abstract Mn is a well-established promoter of Co-based catalysts for enhancing the production of long-chain hydrocarbons via Fischer–Tropsch synthesis (FTS). Revealing mechanistic insights into metal–promoter interactions requires atomically defined Co surfaces with highly controlled addition of Mn. In this study, Mn was deposited onto Co(0001) single crystals to tune Mn:Co ratios relevant to FTS, while X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy were used to access the electronic and chemical alterations. Scanning tunneling microscopy revealed the MnO decoration on Co(0001) while density functional theory (DFT) was employed to correlate the atomic structure of MnO on Co(0001) and its effect on the valence band spectra. Solid–gas interactions were investigated in various atmospheres enabling in situ correlation among surface composition, structure, and catalytic conditions. We find a substrate-induced growth of MnO clusters on the Co(0001) surface. Valence band spectra and DFT calculations reveal a charge transfer between Mn and Co at the MnO–Co interface and alterations of the chemical structures. Moreover, in the presence of Mn under relevant FT reaction conditions, CO dissociation and formation of carbonaceous intermediates (–C/–CH) are enhanced, which highlights the promotional role of Mn in facilitating key steps of the Fischer–Tropsch reaction.