Interconnected hollow metal–organic framework network towards excellent proton transfer for proton exchange membrane

Abstract

Interconnected hollow metal–organic framework (MOF) network (GO@HZIF-8) was designed as an efficient proton transfer accelerator in Nafion membrane. GO@HZIF-8 was constructed by in situ synthesis of ZIF-8 onto graphene oxide (GO) and succedent etching with tannic acid (TA). The hollow construction and surface TA functionalization of hollow ZIF-8 (HZIF-8) bestowed composite membrane with superior water retention. This was highly beneficial to the rapid proton transfer. Besides, the hollow construction could effectively reduce the proton transfer resistance onto GO@HZIF-8. More importantly, the interconnective architecture between HZIF-8 by the tethering function of GO and the interfacial hydrogen bond interaction between GO@HZIF-8 and Nafion resulted in connective proton transfer routes at GO@HZIF-8 surfaces and GO@HZIF-8/Nafion interfaces. These dramatically accelerated the proton transfer of GO@HZIF-8/Nafion composite membrane, enabling a considerable proton conductivity (PC) of 0.301 S cm−1 under 90 °C, 95 % RH, ∼1.33-fold greater than that of the pure Nafion membrane (RN). Moreover, the composite membrane exhibited a peak power density of 45.8 mW cm−2, ∼1.22-fold higher than that of RN. These results menifest that constructing hollow MOF network possesses grand prospect in the construction of high performance proton exchange membranes (PEMs).