Static Disorder Approach in Friction Force Microscopy of Catalyst Powder in Ethanol Reveals High Corrugation Energy

We study catalyst powder involved in reverse water-gas-shift (RWGS) reaction, Fe-Al-O spinel, using Friction Force Microscopy (FFM) in ethanol. The catalyst is synthesized as aggregates of nanoparticles of Fe-Oxide phase produced from the Fe-Al-O spinel, and its powder was immobilized in Tempfix adhesive, in order to perform lateral friction force measurements. The FFM measurements resulted with intermittent stick-slip events with large variance in the slip forces and in their spatial distribution, indicating amorphous arrangement of the surface structure. The activity of the surface was manifested through the load dependent friction force. Motivated by the stochastic nature of the stick slip patterns, we estimated the corrugation potential energy of the measured catalyst with a static disorder (SD) based model and compared it to an averaged version of the Prandtl-Tomlinson (PT) model. The two models showed close proximity of the energy values and their trend with the applied normal load. The reconstructed values revealed high corrugation surface potential for the catalyst.