Instability phenomena in catalytic hydrogen oxidation studied on a nano-scale by a field electron microscope

Abstract

A nm-sized field emitter tip made of Rh resembles a Rh nanoparticle typically employed in industrial catalysis. Such a tip can be imaged in a field emission microscope (FEM) allowing thus studying catalytic reactions in situ. Due to the high applied electric voltages (up to 10000 V) inherent in FEM, the problem of the sample temperature control which is crucial in performing catalytic experiments, arises. A novel temperature control and sample heating system based on wireless data transmission was constructed and built, and studies of hydrogen oxidation on Rh were performed to demonstrate the advantages of the new technique. Oscillations as well as catalytic ignitions and extinctions in the hydrogen oxidation reaction on a nm-sized Rh sample were observed by FEM for the first time. Collected data were used for the construction of the kinetic phase diagram of the catalytic hydrogen oxidation reaction on nm-sized Rh sample.