Pseudo Single-Atom SiO _<i>x</i> –Co Interfaces for Selectivity Control in Fischer–Tropsch Catalysis

Fischer–Tropsch synthesis (FTS) is a cornerstone catalytic process for converting synthesis gas into liquid hydrocarbons, yet it suffers from limited selectivity and excessive methane formation. Here, we demonstrate that surface modification of cobalt oxide (Co3O4) nanoparticles with trimethylchlorosilane (TMCS), followed by calcination, yields pseudo single-atom SiOx species that form a distinct SiOx–Co interface. Unlike conventional silica coatings, these isolated SiOx moieties are ligand-like, electronically modifying surface cobalt atoms, without forming bulk SiO2 or siloxane domains. This interface enhances π-back-donation to carbon monoxide (CO), increases the heat of adsorption, and promotes CO bond cleavage, as confirmed by CO chemisorption and CO-temperature-programmed desorption (TPD). Catalysts modified in this way show over an order of magnitude increase in turnover frequency (TOF), alongside a marked decrease in methane selectivity and a shift toward C2–C5 hydrocarbons and oxygenates. These findings establish pseudo single-atom SiOx–Co interfaces as a powerful route to engineer activity and selectivity in FTS. Importantly, the approach avoids chlorine residues and is consistent with Cl removal during calcination. Beyond suppressing methane, the SiOx interface selectively promotes aldehydes, aligning with recent reports on oxide-modified Co catalysts. Pseudo single-atom oxide–metal interfaces emerge as a tunable strategy for enhancing both activity and selectivity in cobalt-based FTS catalysts.