Strategic hierarchical improvement of superprotonic conductivity in a stable metal-organic framework system

Identification of proton-exchange membranes (PEMs) with high proton conductivity and long-term durability is highly important for the development of fuel cells. Herein, an efficient and feasible strategy that features different proton sources and hopping site modifications on the stable UiO-66-NH 2 framework for hierarchically improving the proton conductivity is demonstrated. As a result, IM-UiO-66-AS showed the highest superprotonic conductivity of 1.54 × 10 −1 S cm −1 (80 °C, 98% RH) and outstanding long-term durability of at least 100 h, which surpass those of all the reported proton-conducting MOF materials without guest loading. Furthermore, the manufactured membrane could maintain a high proton conductivity of 1.19 × 10 −2 S cm −1 even with continuous work for at least 40 h under the same conditions, suggesting its great potential for further application in devices. An efficient strategy to hierarchically improve the proton conductivity of MOFs by increasing the number of proton sources and hopping sites has been proposed.