The catalytic reduction of NO2 with hydrogen on a Pt field emitter tip is investigated using both field electron microscopy (FEM) and field ion microscopy (FIM). A rich variety of nonlinear behavior and unusually high catalytic activity around the {012} facets are observed. Our FEM investigations reveal that the correlation function exhibits damped oscillations with a decaying envelope, showing that molecular noise will influence the dynamics of the oscillations. The dependence of the oscillatory period on the P-H2/P-NO2 pressure ratios is analyzed. Similar patterns are reported under FIM conditions. Corresponding density functional theory (DFT) calculations for the adsorption of NO2 on Pt {012} in the presence of an external electric field are performed in order to gain an atomistic understanding of the underlying nonlinear phenomena.