One-Step Reductive Electrodeposition of MOF Film on Polymer Membrane

Reductive electrodeposition is a technique for the preparation of substrate-supported MOF films but is generally incompatible with poorly or nonconductive substrates like polymers and suffers from the possible codeposition of metallic impurities. Here, we report a facile and inexpensive strategy that achieves one-step reductive electrodeposition of impurity-free MOF films (i.e., HKUST-1 film) on nonconducting poly(ether sulfone) (PES) membranes. Unlike previously reported reductive electrodeposition configurations, which only contain the electrode–electrolyte interface near the working electrode, there are two tandem interfaces in the proposed approach, namely, the electrode–membrane interface and the membrane–electrolyte interface. Owing to the counter-diffusion of ions across the polymer membrane, this strategy allows the generation of MOF units on the membrane–electrolyte interface, while the codeposition of metal happens on the other, resulting in the deposition of a pure MOF film on untreated polymer membranes. Importantly, thanks to the inherent “self-closing” ability of the proposed electrochemical approach, a compact polycrystalline HKUST-1 film supported on PES membrane was obtained under mild conditions, which exhibited a rejection of 98.7% for rose bengal in an aqueous solution with a permeance of 7.4 L m–2 h–1 bar–1.