Study On Structure Regulations Of Functionalized Graphene And Their Organic Catalytic Properties

Graphene is a single-atom layer two-dimensional structural of sp2 hybridized carbon material.The specical structural of graphene endows with unique physical and chemical properties,which was making them as promising catalysts for various organic catalytic processes.In addition,though theoretical computational chemistry combining with surface science technology,graphene can serve as an ideal model to understand the real active sites and surface reaction process of catalysts.Therefore,the study graphene-based catalysts have the significance obviously for both of fundamental research and practical application.In this paper,several graphene based catalysts were designed and synthesized,various characterization methods were used to systematically analyze the accurate microstructure of the catalysts.The catalytic active site and structure-activity relationship was studied by measurement the catalytic activity of the obtained catalysts for a verious organic reaction process,and then the surface catalytic behavior and reaction mechanism of the catalysts were also proposed.At first,the Cu nanoparticles loaded N-doped graphene(Cu-N-rGO)catalyst was obtained through a very simple one-pot solvothermal process,which was demonstrated as a high-efficient green protocol for catalytic oxidation of inert Csp3-H bonds functionalization only with oxygen as the only oxidant.Remarkably,the newly-prepared Cu-N-rGO shown 34.5%conversion and 89.2%selectivity for the catalytic oxidation of cyclohexane to KA oil in a single cycle.The Cu-N-rGO possessed good stability because of the doped nitrogen-atoms leads to a strong interaction between the Cu species and graphene,so that the conversion and selectivity maintained well after 5 runs.The delicate relationship of Cu NPs and nitrogen has been investigated by accurately control the ratio of the nitrogen and Cu in the doped graphene,and the synergistic effect of Cu NPs and N-doped graphene on facilitating the oxidation process also has been elucidated.It is critical to find a purposeful control on the synthetic process on the Cu NPs of the catalyst with accurately difference Cu phases,but it still remains a challenge.As a result,a simple,efficient and scientific Cu-MOFs derived synthetic strategy for uniformly dispersed two phases Cu/Cu2O-rGO was introduced.The strategy mainly includes an innovative MOFs jacket-structure "take" and "off" process.The newly fabricated Cu/Cu2O-rGO catalyst allows the Cu species to be reversibly oxidized and reduced through electron transfer between Cu phase and Cu2O phase.The synergistic effect of between Cu/Cu2O phases and graphene to lead the material works as excellent heterogeneous noble metal free catalysts for the Sonogashira cross-coupling reactionsNon-noble metal catalyzed hydrogen atom transfer(HAT)process for immediate CSp2-H bond activation has been a distinct approach to the synthesis of functionalized aromatic compounds.First of all,the Cu2O nanoparticles(Cu2O NPs)doped graphene(Cu2O-rGO)catalyst was successfully synthesized via a MOF-derived strategy.In summary,we have introduced a radical capture mechanism which which involvement of Benzene-centered radical(·C)and Oxygen-centered radical(-OH)for immediate catalytic oxidation of benzene to phenol at mild conditions.By using the heterogeneous Cu2O-rGO catalyst,there are two key roles of the Cu2O NPs in this catalytic protocol:(i)to generate-OH,and(ii)to capture the ·C which could as a potential approach to overcome the C·H bond activation problem and provide a general paradigm to the development of carbocatalysis reactionsCu has been considered as a potential catalyst for direct functionalization of unactuated alkane C-H bond to the largely improved utility value of fine chemistry.Here,we outline a stepwise dual-radical mechanism which involvement of Carbon-centered radical(·C)and Oxygen-centered radical(·OH)to overcome the sluggish Cu oxidative addition problem.The·OH generate form the H2O2 activation of the heterogeneous Cu2O-graphene nanocomposite(Cu2O/G)catalyst with significant peroxidase-like activity,then the·OH could initiate a HAT process to form the·C.This·C/·OH dual radical-mediated fragment coupling strategy was applied to allow for the development of a general approach for the direct construction of alkane C-O bond via the heterogeneous Cu2O/G catalyst.Nitrogen-doped carbon graphene(N-rGO)have shown great application potential in the catalyst and materials science fields.In this paper,a heterogeneous N-rGO based catalytic process for H2O2 activation and evergreen and environmentally Dakin reaction was designed,completely without using any transition metals and homogeneous bases.The heterogeneous catalyst shown excellent structure and chemical stability,could be reused for several cycles with only a minor decrease in catalytic efficiency.The study of catalyst structure and catalytic activities indicated that the specific enhanced active sites were mainly created by graphitic N The C-(HOOH)and C-O*(C-O-)species on the o-carbon mediated by the graphitic N was the key transition state for catalysing H2O2 activation and Dakin reaction.