Enhanced Catalytic Hydrogenation Performance of Rh-Co₂O₃ Heteroaggregate Nanostructures by in Situ Transformation of Rh@Co Core–Shell Nanoparticles

Abstract

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-Co2O3 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-Co2O3 heteroaggregate nanostructures are obtained by calcination of Rh@Co nanoparticles and subsequent selective H2 reduction. The Rh-Co2O3/Al2O3 nanostructures demonstrated enhanced catalytic performance for hydrogenations of various substituted nitroaromatics relative to individual Rh/Al2O3 and illustrated a high catalytic stability during recycling experiments for o-nitrophenol hydrogenation reactions. The catalytic performance enhancement of Rh-Co2O3/Al2O3 nanocatalysts is ascribed to the Rh-Co2O3 interfaces where the Rh-Co2O3 interaction not only prevents the active Rh particles from agglomeration but also promotes the catalytic hydrogenation performance.

Highly Selective Nitrite Hydrogenation to Ammonia over Iridium Nanoclusters: Competitive Adsorption Mechanism

“…The lattice spacing of Ir nanoclusters was 0.221 nm, matching with the Ir(111) plane. 25 The binding energies at 60.9 and 63.9 eV of X-ray photoelectron spectroscopy (XPS) were assigned to 4f 7/2 and 4f 5/2 of the Ir 0 species (Figure S1), 26 suggesting that most of the surface Ir species existed in the metallic state. The X-ray diffraction (XRD) patterns showed a mixed phase of rutile and anatase of TiO 2 , with no clear characteristic peaks of Ir(111) observed, potentially due to low metal loading and the good dispersion of small Ir nanoclusters (Figure S2).…”

“…High resolution transmission electron microscopy (HRTEM) images of 1 wt % Ir/TiO 2 showed the dispersed Ir nanoclusters on the TiO 2 surface, with an average particle size of 1.63 ± 0.02 nm (Figure a,b). The lattice spacing of Ir nanoclusters was 0.221 nm, matching with the Ir(111) plane . The binding energies at 60.9 and 63.9 eV of X-ray photoelectron spectroscopy (XPS) were assigned to 4f 7/2 and 4f 5/2 of the Ir 0 species (Figure S1), suggesting that most of the surface Ir species existed in the metallic state.…”

A “Green” Concentrated Solar Light Doping Strategy for Significantly Improved Photoelectrochemical Performance

“…The core-level XPS of Co 2p of Co/CSL-TiO 2 NTPCs was presented in Figure b. Two peaks with binding energies of 779.45 and 794.75 eV can be assigned to Co 2p 3/2 and Co 2p 1/2 , respectively, which indicated the formation of Co–O bonds but were slightly differentiated from the reported values of cobalt oxides. − In addition, as shown in Figure c, the core-level XPS of Ti 2p presented Ti 2p 3/2 and Ti 2p 1/2 binding energies at 458.5 and 464.3 eV, respectively, for CSL-TiO 2 NTPCs, and 458.2 and 463.9 eV, respectively, for Co/CSL-TiO 2 NTPCs. The negative shift of Ti 2p binding energy after Co doping can be ascribed to the higher accumulation of electrons on Ti due to the electron donated from cobalt .…”

Formulation of Nanostructured Heteroaggregates by Fluidization Technologies

“…They have shown high potential and superior performance compared to homoaggregates in different fields of application. For instance, in catalysis (e.g., [1][2][3]), sensing [4], drug delivery [5], generation of synthetic bone grafts [6] and anti-cancer therapy [7]. In the field of renewable energies, important advances are attributed to hetero-junctions, e.g., by tuning of the band gap [8][9][10] allowing utilization of a broader range of the solar spectrum in photovoltaic applications.…”