Figure 5
(a) Reference XAS spectra at the Co L-edge of reduced Co NPs (bottom spectrum) and oxidation states after heating under 100 kPa of O2 at different temperatures. (b) Reduction of the oxidized NPs (bottom spectrum) under 100 kPa of H2 at different temperatures. (c) XAS spectrum of the O K-edge region after first exposing the reduced nanoparticles to a mixture of CO and He and then to pure He or H2. (d) Scanning electron microscope image of the 15 nm cobalt NPs as prepared. |