Jichao Wei

Novel polysiloxane resin functionalized with dicyclohexano-18-crown-6 (DCH18C6): Synthesis, characterization and extraction of Sr(II) in high acidity HNO3 medium

A novel kind of polysiloxane resin functionalized with dicyclohexano-18-crown-6 (DCH18C6) was synthesized through a post-modification approach. The DCH18C6 moieties bearing amino groups were firstly prepared, followed by covalent grafting to a silica precursor P-(CH(2))(3)-Cl (Where P represents a 3-dimentional polymerized silica matrix) based on nucleophilic substitution reaction. (29)Si and (13)C solid-state NMR, FT-IR, XPS, TGA, ESEM and elemental analysis were employed to systematically characterize the structure, thermal property and surface morphology of the functionalized resin. The results indicated that the DCH18C6 ligands were successfully bonded to the polysiloxane resin with a satisfactory grafting degree (33.6wt.%). Due to the robust organosilica framework and the covalent immobilization of the ligands, the functionalized resin had excellent thermal stability and acid resistance. Batch experiments showed that the resin could effectively separate Sr(II) in high acidity mediums. The distribution coefficient (K(d)) of 43.6cm(3)/g could be achieved in 5.0mol/L HNO(3) solution. The influences of contact time and acidity of HNO(3) on the resins extraction performance were examined. The reusability and the selectivity to Sr(II) over interference ions were investigated. The DCH18C6-functionalized resin might be potentially applied for the radiostrontium removal in the high level liquid waste (HLLW).

High performance of stretchable carbon nanotube–polypyrrole fiber supercapacitors under dynamic deformation and temperature variation

Flexible fiber-shaped supercapacitors have great potential in wearable electronic devices. Here, we fabricate CNT–PPy composite films by an electrochemical deposition method from macroscopic CNT films. The composite films are transformed into flexible fibers with ultralow density by drawing through several diamond wire-drawing dies. The CNT–PPy fibers have outstanding electrochemical properties with a high specific capacitance of 302 F g−1 in 1 M H2SO4 liquid electrolyte. Flexible, stretchable, all-solid-state, fiber-shaped supercapacitors are then fabricated from the CNT–PPy fibers using H3PO4–poly(vinyl alcohol) as gel electrolyte. The supercapacitor has a high specific capacitance of 69 F g−1, a high power density and an energy density of 3.8 kW kg−1 and 3.6 W h kg−1, respectively. The fiber-shaped supercapacitor also exhibits high stability and reliability under static and dynamic stretching, and also in a wide temperature range from −27 °C to 61 °C.

Fabrication of high quality perovskite films by modulating the Pb–O bonds in Lewis acid–base adducts

High efficiency perovskite solar cells can be made through the Lewis adduct approach. The interaction between PbI2 and the Lewis base is a key factor to make high quality perovskite films. Here, we combine a two-step method with the Lewis adduct approach to fabricate high quality organometallic perovskite films by tuning the strength of the Pb–O bond in Lewis acid–base adducts via adding different Lewis base additives. By optimizing the strength of the Pb–O bond, smooth CH3NH3PbI3 films with large perovskite grains are prepared. The high quality CH3NH3PbI3 films lead to a low recombination rate, long carrier life time and highly efficient charge transfer process. As a result, the power conversion efficiency of the best perovskite solar cell increases from 12.79% to 17.26%.

Synthesis of new silica gel adsorbent anchored with macrocyclic receptors for specific recognition of cesium cation

In this article, a new class of silica gel adsorbent functionalized with macrocyclic receptors was developed for cesium recognition. A calixcrown molecule, with strong affinity to cesium cation, was decorated precisely at the 1,3-alternate benzene rings with reactive amino substituents, followed by the anchoring to the silica matrix to obtain a high functionalization degree. Structural characterization of the monomers and the organosilicas was carried out by 1H/13C NMR, 29Si/13C solid-state NMR, and FT-IR spectra. Besides, XPS survey, BET, TGA and ESEM were employed to investigate the surface property, thermal stability and micro-morphology of the organosilicas. Due to the host–guest interaction between the calixcrown receptor and cesium cation, efficient separation of cesium in the presence of competing alkali metals including sodium and potassium was realized. Mechanism regarding the recognition effect was discussed. The calixcrown-grafted organosilica material possesses the potential to be applied for the separation of cesium in radioactive liquid waste.

A novel well-ordered mesoporous organosilica specialized for highly selective recognition of Pb(II) by host–guest interactions

The first example of well-ordered mesoporous organosilica with high selectivity towards Pb(II) based on host–guest interactions was developed. Due to the high functionalization of a specific macrocyclic host, DCH18C6, with easy accessibility, the mesoporous organosilica showed remarkable recognition and efficient adsorption of Pb(II) in a multicomponent system.

Site‐Selective Functionalization of Periodic Mesoporous Organosilica (PMO) with Macrocyclic Host for Specific and Reversible Recognition of Heavy Metal

A novel kind of macrocyclic-host-functionalized periodic mesoporous organosilica (PMO) with excellent and reversible recognition of Pb(II) was developed. The macrocyclic host molecule cis-dicyclohexano[18]crown-6, with strong affinity to Pb(II), was carefully modified as a bridged precursor to build the PMO material. To break down the limit of the functionalization degree for PMOs incorporated with large-sized moieties, a site-selective post-functionalization method was proposed to further decorate the external surface of the PMO material. The selective recognition ability of the upgraded PMO material towards Pb(II) was remarkably enhanced without destroying the mesoporous ordering. Solid-state (13)C and (29)Si NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), XRD, TEM, and nitrogen adsorption-desorption isotherm measurements were utilized for a full characterization of the structure, micromorphology, and surface properties. Reversible binding of Pb(II) was realized in the binding-elution cycle experiments. The mechanism of the supramolecular interaction between the macrocyclic host and metal ion was discussed. The synthetic strategy can be considered a general way to optimize the properties of PMOs as binding materials for practical use while preserving the mesostructure.