Functionalized metal-organic frameworks (MOFs) are being extensively developed as viable fillers to enhance the proton conductivity of proton exchange membranes . Herein, an amino-pendant sulfonic acid bi-functionalized MOFs material (UNCS)-doped SPEEK membrane with low degree of sulfonation (DS) can improve the proton conductivity as well as maintain the membrane dimensional stability. UNCS can act as bridges of proton donors and acceptors to reduce the activation energy barrier and shorten the distance of long-range proton conduction. Among all as-prepared membranes, SPEEK/UNCS-3 exhibited the highest proton conductivity of 186.4 mS·cm −1 at 75 °C and 100% relative humidity (RH), which is much greater than that of pristine SPEEK and Nafion 117. Benefiting from the acid-base pair interaction between the amino groups of UNCS and the sulfonic acid groups of SPEEK, the dimensional stability and mechanical properties of the composite membranes were enhanced. More interestingly, STEM-HAADF and SAXS characterization consistently revealed that UNCS served as bridges among proton channels in the composite membranes for continuous proton transport.
Bingying Jia,Miaojiang Wu,Hua Zhang,Yi Zeng,Gongying Wang
Titanates are frequently used as precursors to prepare transesterification catalysts with TiIV species. Unfortunately, it is challenging to control the dispersity of TiIV active sites on supports. Herein, a series of TiIV species is anchored on abundant linker vacancy sites by introducing point and large scale defects in UiO-66(Zr/Ti) with hierarchical-pore structure. The catalyst functionalized by titanium(IV) oxide bis(2,4-pentanedionate) shows excellent catalytic performance in the transesterification of dimethyl carbonate with phenyl acetate. The catalysts are characterized by XRD, FT-IR, N2 adsorption–desorption, XPS, SEM and STEM-HAADF techniques. The results demonstrate that the delicate mesopores in the support can not only exhibit a large surface area for the distribution of the active sites, but also provide better mass transfer performance. Meanwhile, the introduction of octahedral TiIV ions raises the activity of the catalyst via more coordinatively unsaturated ZrIV sites. Furthermore, using titanium(IV) oxide bis(2,4-pentanedionate) as a Ti source can effectively prevent the condensation of tetrahedral TiIV species anchored on the hierarchical-pore UiO-66(Zr/Ti) support.
危险品化学品经营许可证（带存储）