Fig. 1: Operando transmission electron microscopy (TEM) of Pd nanocube and nano-octahedron catalysts during a CO oxidation reaction.
From: Periodic structural changes in Pd nanoparticles during oscillatory CO oxidation reaction
STEM and TEM images of a cuboidal and b octahedron Pd nanoparticles (NPs) at different temperatures and under 760 Torr of 10% CO, 18% O2, and 72% He gas environment corresponding to a gas pressure ratio of \({p}_{{{{{{\rm{CO}}}}}}}/{p}_{{{{{{{\rm{O}}}}}}}_{2}}\approx 0.5\)). Changes in gas compositions during the CO oxidation reaction over c nanocubes and d nano-octahedrons at different temperatures as indicated by orange step curves. The reaction oscillates for the nano-octahedrons, while the nanocubes do not show such oscillatory reactivity. In terms of the NP morphology, the sharp corners of nano-octahedrons in b become rounded as they switch to a high-activity state at 360 °C, whereas the nanocubes in a remain unchanged, and their activity increases very little at elevated temperatures.
