Preparation And Catalytic Performance Of Boron Nitride Nanosheets Supported Cu₂O Nanoparticles

Despite Cu₂O nanoparticles(Cu₂O NPs)active in the reduction of p-nitrophenol(4-NP)to p-aminophenol(4-AP),their obviously lower catalytic efficiency than noble metal catalysts(Au,Ag,Pt,etc)make them limited for practical application.Size control of Cu₂O NPs is the crucial factor for exhibiting excellent catalytic activity.The weak stability limits its widespread and practical application.Therefore,increasing efforts have been devoted by dispersing Cu₂O NPs on various supporting substrates.Boron nitride nanosheets(BNNSs),a structural analogue of graphene,is a robust supporting substrate owing to its advantages of unique physical and chemical properties.The d_z²orbital of Cu₂O overlaps with the p_zorbital of B and N in BNNS,which enhance the surface binding ability of them.BNNSs as a two-dimensional supporter is appealing candidates due to its high surface area which exposing more high active sites.BNNSs has different electronic structures from graphene.In the Na BH₄reduction 4-NP reaction,the adsorption of hydrogen on BNNSs surface can change its physical properties,which can prevent Cu₂O NPs from being oxidized into Cu O.Thus,boron nitride nanosheets is an ideal support to immobilize Cu₂O NPs with good dispersion.In this study,a novel kind of Cu₂O/BNNSs-OH supported catalyst with high dispersity,highly catalytic efficiency,and stability was facilely fabricated via a controllable liquid phase reduction of ascorbic acid and combining with an annealing process.Moreover,the catalytic activity was investigated by the reduction reaction of 4-nitrophenol.(1)a gentle water freeze-thaw technique,with a particular focus on the use and efficacy of polyvinylpyrrolidone(PVP)as a dispersant,is put forth as a novel and efficient approach for exfoliation of BNNSs in a large yield and high concentration.Structure and morphology of the samples were characterized by scanning electron microscopy(SEM),high resolution transmission electronic microscopy(HRTEM),atomic force microscopy(AFM),x-ray powder diffraction(XRD),x-ray photoelectron spectroscopy(XPS)and Raman spectroscopy.Five vital factors,surfactant type,initial parent material concentration,PVP ratio,centrifugation(CF)rate and freeze-thaw cycle mainly influence the final concentration of inorganic nanosheets.What's more,the exfoliated h-BN nanosheets were found to be stably dispersed by low-temperature storage.(2)this wild freeze-thaw method not only paves the way for wide applications,but also can be versatile,having been used to produce dozens of different 2D nanosheets,such as Mo S₂and Mo O₃nanoflakes,in large yields.The structure and morphology of the 2D matrials were characterized by various characterization methods.Therefore,the PVP assisted freeze-thaw method opened up a potential way for large scale production of high quality 2D nanosheets.(3)High performance Cu₂O/BNNSs-OH catalysts were obtained by dispersing Cu₂O NPs on BNNSs via functionalized modifications,liquid phase reduction of ascorbic acid and combining with an annealing process.Meantime,the morphology and particle size of Cu₂O NPs were controlled by p H value and mixing ways.Moreover,the catalytic activity was investigated by the reduction reaction of 4-nitrophenol.It is found that Cu₂O/BNNSs-OH with high catalytic activity similar to the noble metal catalyst.