Electrochemical synthesis of metal organic framework films with proton conductive property

Abstract

It is a big challenge to construct proton-conductive metal organic framework (MOF) films for successful utilization of MOF materials in proton-conducting devices. Herein, we propose an electrochemical strategy for the preparation of highly porous NENU-3 films on the conductive copper substrates. The Keggin-type heteropolyacid of phosphotungstic acid (PTA) as the molecular clusters is integrated into Cu3(BTC)2 cavities by the one-step electrochemical approach. The PTA plays a dual role of guest molecules in the cages as well as a strong electrolyte in the synthesis solution. Further, as-prepared NENU-3 films exhibit a fascinating proton conductivity under ~97% RH and at 24°C, possibly originating from the Keggin PTA clusters, as proton carriers and the hydrophilic framework of Cu2 (BTC)3. This study may offer a new strategy to assemble the proton-conductive MOF films, and the good combination of heteropolyacids and MOF host materials presents a promising platform for expanding the applications of MOFs in electrochemical devices.