Rich surface Co(iii) ions-enhanced Co nanocatalyst benzene/toluene oxidation performance derived from Co^IICo^IIIlayered double hydroxide

Abstract

A hierarchical CoCo layered double hydroxide (LDH) nanostructure was constructed through a facile topochemical transformation route under a dynamic oxygen atmosphere. Self-assembled coral-like CoAl LDH nanostructures via the homogeneous precipitation method were also inspected under different ammonia-releasing reagents and solvents. Benzene and toluene were chosen as probe molecules to evaluate their catalytic performance over the metal oxide CoCoO and CoAlO calcined from their corresponding LDH precursors. Nanocatalyst of trivalent Co ions replaced Al(3+) ions in the bruited-like layer had a higher catalytic activity (T99(benzene) = 210 °C and T99(toluene) = 220 °C at a space velocity = 60 000 mL g(-1) h(-1)). Raman spectroscopy, XPS and H2-TPR demonstrated the existence of abundant high valence Co ions that serve as active sites. TPD verified the types of active oxygen species and surface acid properties. It was concluded that the high valence Co ions induced excellent low-temperature reducibility. Surface Lewis acid sites and the surface Oads/Olatt molar ratio (0.61) played relevant roles in determining its catalytic oxidation performance. Our design in this work provides a promising approach for the development of nanocatalysts with exposed desirable defects.

Co3O4 Nanoparticles Anchored on Selectively Oxidized Graphene Flakes as Bifunctional Electrocatalysts for Oxygen Reactions

“…Therefore, the components #1, 1’ at lower BE in the two main peaks Co 2p 3/2 and 2p 1/2 are tentatively assigned to Co(III) and the components #2, 2’ at higher BE are correspondingly assigned to Co(II). To the best of our knowledge, this type of Co peak attribution has been also observed in all the published works on Co 3 O 4 ‐based materials ,,,. Considering this assignment, Co(III)/Co(II) atom ratio was estimated to be 2.2 for pure Co 3 O 4 nanoparticles, which is slightly higher than the predicted value of 2 for Co(III)/Co(II) ratio in the Co(II)Co(III) 2 O 4 spinel structure.…”

Insights on the One‐Pot Formation of 1,5‐Pentanediol from Furfural with Co−Al Spinel‐based Nanoparticles as an Alternative to Noble Metal Catalysts

“…Their crystallite size increased from ca. [25,26] Both Al 3 + sites from alumina phases and, according to previous reports, [12,[27][28] Co 3 + cations from the Co 2 AlO 4 spinel phase could be responsible for the absorption of furfural; whereas, the higher dispersion of Co 0 (based on its lower particle size, ca. In addition, TG analyses of the different reduced catalysts were performed to tentatively determine the amount of metallic Co in the catalyst from the mass gain produced through the oxidation of Co 0 to Co 2 O 3 in air ( Figure 4C and D).…”

Integrated Cobalt Oxide Based Nanoarray Catalysts with Hierarchical Architectures: In Situ Raman Spectroscopy Investigation on the Carbon Monoxide Reaction Mechanism

“…Deconvolution of the Co 2p spectra shows that the Co 2p 3/2 spectrumc onsistso ft wo components (Co 3+ + and Co 2+ + ) and two shake-ups atellite peaks (Figure 7a). [27][28][29] The two major peaks of Co 2p 3/2 at ab inding energy (BE) of 779.6 and 781.4 eV correspond to the Co 3+ + and Co 2+ + oxidations tates,r espectively.T he other two peaks at BE = 784.3 and 788.2 eV are associated with the shake-up satellites of Co 3+ + and Co 2+ + ,r espectively.T he surfaceC o 3+ + /Co 2+ + atomic ratios are given in Ta The O1sc urves are asymmetrica nd complicated because of the presence of more than one peak that arises from the overlapping contributions of different chemical oxygen species (Figure 7b). To differentiate between these oxygen species, the O1sc urvesc an be deconvoluted into two peaks (O latt and O ads ).…”

“…Deconvolution of the Co 2p spectra shows that the Co 2p 3/2 spectrumc onsistso ft wo components (Co 3+ + and Co 2+ + ) and two shake-ups atellite peaks ( Figure 7a). [27][28][29] The two major peaks of Co 2p 3/2 at ab inding energy (BE) of 779. 6 The O1sc urves are asymmetrica nd complicated because of the presence of more than one peak that arises from the overlapping contributions of different chemical oxygen species (Figure 7b).…”