Self-organization of unimolecular micelles in beam stream for functional mesoporous metal oxide nanofibers

The use of linear amphiphilic block copolymers as templates is an important method for the preparation of mesoporous materials.However,the obtained assemblies are usually sensitive to synthetic conditions,which impedes the preparation of such mesoporous materials in certain environments.Herein,we report a universal strategy applying an amphiphilic multiarm triblock copolymer in the preparation of mesoporous metal oxide nanofibers(NFs)using one metal oxide(TiO_(2),ZrO_(2),WO_(3),CeO_(2)),or two(TiO_(2)/WO 3,TiO_(2)/ZrO_(2),TiO_(2)/CeO_(2))and three(TiO_(2)/WO_(3)/CuO)metal oxides as composites.The template consists of modified β-cyclodextrin as the center of the macromolecule which is attached sequentially to a block of polystyrene,poly(acrylic acid),and poly(ethylene oxide).Under electrospinning conditions,stable unimolecular micelles are formed and effectively co-assemble with metal ions to form fibrous nanostructures.As indicated by various characterization methods,the synthesized TiO_(2) and its derived composite NFs maintain a straight and continuous fibrous structure after calcination,and TiO_(2) NFs exhibit uniform mesopores of 10.8 nm in diameter and a large Brunauer-Emmett-Teller surface area of 143.3 m^(2)g^(−1).Benefiting from the characteristic structure,still present after modification,Pt-decorated mesoporous TiO_(2) NFs display excellent ability in the visible-light photocatalytic degradation of tetracycline,which is superior to the commercial P25 catalyst.This study reveals a promising strategy for the preparation of fibrous mesoporous metal oxides.

Oriented assembly of monomicelles in beam stream enabling bimodal mesoporous metal oxide nanofibers

The assembly of monomicelles along onedimension(1D)to construct tubular or fibrous mesostructures is greatly desired but still challenging.Herein,we have demonstrated a facile strategy to synthesize 1D bimodal mesoporous metal oxides(e.g.,WO_(3),WO_(3)/Pd,WO_(3)/Pd Cu,TiO_(2),and ZrO_(2))nanofibers(NFs)through assembling the organic-inorganic composite monomicelles in a beam stream generated via an electrospinning technique.This facile and repeatable methodology relies on the preparation of copolymer@metal-complex monomicelles in an anisotropic solution and oriented assembly of them in the beam stream by the selective evaporation of solvent.WO_(3)and its derivatives are chosen as the demo,which show a uniform continuous fibrous structure with dual mesopore sizes(~4.0 and 7.6 nm)and large surface area(~93.1 m^(2)g^(-1)).Benefitting from the unique textual structure,gas sensors made by Pd-decorated mesoporous WO_(3)NFs display outstanding comprehensive sensing performance to ethylbenzene,including a high sensitivity(52.5),an ultralow detection limit(50 ppb),and fast response/recovery kinetics(11/16 s)as well as an outstanding selectivity,which render them promising for rapid environmental monitoring.