Surface potential energy of spinel catalyst from atomic friction measurements

Itai Shahar, Chemical Engeneering, Ben Gurion University of the Negev, Tel Aviv, Israel

 

Surface potential is related to many physical and chemical processes including catalysis, adhesion and many more. Friction force microscopy (FFM) can provide high-resolution information, which can give insight on the interfacial interaction potential.  One key challenge is that most surface-active materials are not in a pure crystalline state but rather in an amorphous phase or in a powder state. Here we propose an elegant method for quantifying the surface potential, using the Prandtl-Tomlinson model under static hindrance. This is done by measuring the friction forces along the surface of a spinel catalyst, which is used in RWGS reaction in the process of producing fuel out of CO₂, and its different phases. Accompanied by an estimation of the surface free energy corrugation from force friction measurements we show atomic stick-slip pattern of an amorphous powder. Following by scaling the estimation of the surface energy with different normal loads and extrapolating the surface potential amplitude. We demonstrate that this established catalyst exhibits, as expected, a very high surface potential amplitude with comparison to a non-surface-active material such as NaCl. This provides a proof of concept for the application of FFM in the field of catalyst characterization and design.