Catalytic Impedance Spectroscopy: Concept and Application on CO2 Methanation

Complex modeling of periodic excitation combined with time-resolved product detection is used to describe the complex response function of a catalytic system. We describe this concept of catalytic impedance spectroscopy (CIS) and the underlying general experimental approach and a concrete setup. The feasibility of CIS is experimentally demonstrated along the catalytic CO2 methanation reaction. The measurements confirm the theoretically anticipated rate-determining step of HCO* -> CH* on Ni catalysts. Limitations and prospects of CIS to unravel reaction mechanisms are discussed.