Direct imaging of catalytic surface reactions in the field‐ion microscope: The oxidation of hydrogen on platinum

A field-ion microscope (FIM) was used in the investigation of hydrogen oxidation at temperatures between 300 K and 430 K and pressures of p(O2) = 5 · 10−4 mbar, p(H2) = 3 · 10−4 to 7 · 10−4 mbar. The H2O molecules produced act as an imaging gas and display the catalytically active surface area. The structure-sensitive H2O formation was studied under steady-state conditions or in the oscillatory regime or in form of chemical waves. The displacement of Pt lattice atoms is spectacular in the Pt(100) plane, where the transformation from (1 × 1) Pt(100) to hex Pt(100) can be directly imaged.