Effect of the Preparation Method on Oxidation Over Time of Supported Cu ⁰ Nanoparticles

ABSTRACT Given the recognized instability of copper in air and the propensity of metal nanoparticles to undergo oxidation under ambient conditions, this study compares the stability of Cu nanoparticles supported on TiO 2 synthesized by two methods: the aqueous reduction method and the wet impregnation followed by H 2 reduction method. Over a period of four months, the solids were subjected to extensive characterization by x‐ray diffraction (XRD), N 2 O chemisorption, H 2 ‐TPR and x‐ray photoelectron spectroscopy (XPS). Raman analysis and electron energy loss spectroscopy (EELS) were also employed to map the oxidation states of Cu. Catalytic activity in acceptor‐less dehydrogenation of 2‐octanol was evaluated. The results demonstrate that the Cu nanoparticles prepared by aqueous reduction with NaBH 4 are not fully reduced after synthesis, compared to the one reduced with H 2 . The oxidation occurs first in the outer layer, then progressively extend to the core. The catalyst prepared by aqueous reduction showed a higher Cu dispersion which resulted in higher 2‐octanone productivity.