Department of Chemical and Biomolecular Engineering , University of Connecticut , Storrs , Connecticut 06269 , United States.
ACS Appl Mater Interfaces. 2018 Apr 25;10(16):13542-13551. doi: 10.1021/acsami.7b14308. Epub 2018 Apr 12.
Thin-shelled hollow silica particles are synthesized using an aerosol-based process where the concentration of a silica precursor tetraethyl orthosilicate (TEOS) determines the shell thickness. The synthesis involves a novel concept of the salt bridging of an iron salt, FeCl, to a cationic surfactant, cetyltrimethylammonium bromide (CTAB), which modulates the templating effect of the surfactant on silica porosity. The salt bridging leads to a sequestration of the surfactant in the interior of the droplet with the formation of a dense silica shell around the organic material. Subsequent calcination consistently results in hollow particles with encapsulated iron oxides. Control of the TEOS levels leads to the generation of ultrathin-shelled (∼10 nm) particles which become susceptible to rupture upon exposure to ultrasound. The dense silica shell that is formed is impervious to entry of chemical species. Mesoporosity is restored to the shell through desilication and reassembly, again using CTAB as a template. The mesoporous-shelled hollow particles show good reactivity toward the reductive dichlorination of trichloroethylene (TCE), indicating access of TCE to the particle interior. The ordered mesoporous thin-shelled particles containing active iron species are viable systems for chemical reaction and catalysis.
采用气溶胶法合成了具有薄壳的中空硅纳米颗粒，其中二氧化硅前驱体正硅酸乙酯（TEOS）的浓度决定了壳层厚度。该合成方法涉及到一种新颖的概念，即铁盐（FeCl）与阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）的盐桥作用，这调节了表面活性剂对二氧化硅孔隙率的模板效应。盐桥作用导致表面活性剂在液滴内部被隔离，在有机材料周围形成致密的二氧化硅壳。随后的煅烧过程始终会生成包裹氧化铁的中空颗粒。通过控制 TEOS 的浓度，可以生成超薄壳（约 10nm）的颗粒，这些颗粒在超声作用下容易破裂。形成的致密二氧化硅壳无法进入化学物质。通过脱硅和再组装，可以恢复壳的介孔性，再次使用 CTAB 作为模板。具有介孔壳的中空纳米颗粒对三氯乙烯（TCE）的还原脱氯反应具有良好的反应活性，表明 TCE 可以进入颗粒内部。含有活性铁物种的有序介孔薄壳颗粒是用于化学反应和催化的可行体系。
