High catalytic activity of oriented 2.0.0 copper(I) oxide grown on graphene film

Abstract

Metal oxide nanoparticles supported on graphene exhibit high catalytic activity for oxidation, reduction and coupling reactions. Here we show that pyrolysis at 900 °C under inert atmosphere of copper(II) nitrate embedded in chitosan films affords 1.1.1 facet-oriented copper nanoplatelets supported on few-layered graphene. Oriented (1.1.1) copper nanoplatelets on graphene undergo spontaneous oxidation to render oriented (2.0.0) copper(I) oxide nanoplatelets on few-layered graphene. These films containing oriented copper(I) oxide exhibit as catalyst turnover numbers that can be three orders of magnitude higher for the Ullmann-type coupling, dehydrogenative coupling of dimethylphenylsilane with n-butanol and C–N cross-coupling than those of analogous unoriented graphene-supported copper(I) oxide nanoplatelets.

One‐Step Pyrolysis Preparation of 1.1.1 Oriented Gold Nanoplatelets Supported on Graphene and Six Orders of Magnitude Enhancement of the Resulting Catalytic Activity

“…In a related precedent, it has reported that Cu2O nanocrystals supported on G exhibit a much enhanced catalytic activity. [19] It is known that pyrolysis converts chitosan and other filmogenic natural polysaccharides into G. [20] Apparently, the fibrils of chitosan, the carbonaceous residues derived from them and the evolving N-doped G arrest in each step the growth of Au NPs being also formed simultaneously in the process as consequence of the reductive conditions of the G synthesis and the lack of solubility of Au on carbon. [21,22] While many metals form metal carbides upon heating the metal with carbon at high temperatures, the noble character of Au results in a phase segregation leading to the synchronous formation of N-doped G and Au NPs.…”

Iron Nanoparticles Embedded in Graphitic Carbon Matrix as Heterogeneous Catalysts for the Oxidative C−N Coupling of Aromatic N−H Compounds and Amides

“…It is suggested that, as claimed previously, chitosan and the carbonaceous residues derived therefrom during the different phases of the pyrolysis are thwarting and restricting the growth of the Fe/Co NPs by interacting with them . In related precedents, it has been found that Au, Cu, and even TiO 2 and CeO 2 NPs of relatively small size are formed if the procedure starts with the corresponding metal ions embedded in chitosan.…”

Metal–Polysaccharide Interplay: Beyond Metal Immobilization, Graphenization‐Induced‐Anisotropic Growth

“…In line with this orientation issue, a major breakthrough was recently reported by Garcia et al., where the virtues of chitosan were put in practice not only for graphitization but also to direct metal growth anisotropically (Figure ). Instead of the conventional two‐step strategy that consists of i) graphitization of the polysaccharide followed by ii) metal impregnation, a one‐pot pyrolysis of Cu chitosan brings new perspectives to the selective synthesis of preferential faceted metals or metal oxide particulates on heterogeneous support, where oriented (2 0 0) Cu 2 O grown on graphene films were successfully isolated …”

“…Reduction treatment by hydrogen restores the original (1 1 1) Cu 0 from the former phase. In turn, the presence of Cu in the chitosan film affects the chemical composition of the resulting graphene by completely removing doping with N atoms, which is in sharp contrast to Cu‐free chitosan films that afford N‐doped graphene …”

“…Impressive catalytic behavior of graphene‐supported oriented Cu 2 O was revealed in three typical organic transformations (Ullmann‐like coupling, dehydrogenative coupling of hydrosilanes and alcohols, and C−N coupling) . A major discrepancy was showcased by comparing their catalytic activity with that of the conventional randomly oriented nanosized Cu 2 O supported on the same type of graphene.…”