Pseudo Single-Atom SiO_{toggle="yes">x} –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 (Co₃ O₄ ) nanoparticles with trimethylchlorosilane (TMCS), followed by calcination, yields pseudo single-atom SiO_x species that form a distinct SiO_x –Co interface. Unlike conventional silica coatings, these isolated SiO_x 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 SiO_x –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 SiO_x 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.