Enhanced Catalytic Hydrogenation Performance of Rh-CoO Heteroaggregate Nanostructures by in Situ Transformation of Rh@Co Core-Shell Nanoparticles.

In this work, poly(vinylpyrrolidone)-stabilized 3-5 nm Rh@Co core-shell nanoparticles were synthesized by a sequential reduction method, which was further in situ transformed into Rh-CoO heteroaggregate nanostructures on alumina supports. The studies of XRD, HAADF-STEM images with phase mappings, XPS, TPR, and DRIFT-IR with CO probes confirm that the as-synthesized Rh@Co nanoparticles were core-shell-like structures with Rh cores and Co-rich shells, and Rh-CoO heteroaggregate nanostructures are obtained by calcination of Rh@Co nanoparticles and subsequent selective H reduction. The Rh-CoO/AlO nanostructures demonstrated enhanced catalytic performance for hydrogenations of various substituted nitroaromatics relative to individual Rh/AlO and illustrated a high catalytic stability during recycling experiments for -nitrophenol hydrogenation reactions. The catalytic performance enhancement of Rh-CoO/AlO nanocatalysts is ascribed to the Rh-CoO interfaces where the Rh-CoO interaction not only prevents the active Rh particles from agglomeration but also promotes the catalytic hydrogenation performance.