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-NH2 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.