Control over cathodic deposition of continuous UiO-66 films for ion-selective transport
Sijie Xie, Wouter Monnens, Wei Zhang, Wei Guo, Ning Han, Zhenyu Zhou, Zhenhong Xue, Ivo F.J. Vankelecom, Xuan Zhang, Jan Fransaer
Abstract
Continuous UiO-66 films are promising for ion sieving because of their sub-nanometer-sized apertures and high chemical stability, but their preparation is challenging. Here, we report a direct cathodic deposition of UiO-66 films, which is fast, convenient, and controllable. Electrochemical measurements suggest that lithium nitrate accelerates deprotonation of carboxylic linkers and yields UiO-66 films within 1 h. Material characterizations reveal that the crystallinity of the deposited UiO-66 films improves with deposition temperature and that the morphology is controlled by the molar ratio of the ditopic linker to the monotopic modulator. Crystalline and continuous UiO-66 films are obtained with a linker-to-modulator ratio of 1:120 at 120°C. The anodic aluminum oxide membrane-supported continuous UiO-66 films display excellent selective ion transport performance with a lithium/magnesium selectivity of 286 and a lithium permeance of 11.2 mol m−2 h−1, placing them among the best metal-organic framework (MOF) membranes reported in literature.