Hydrogen-Bonded Metal-Organic Framework Nanosheet as a Proton Conducting Membrane for an H2 /O2 Fuel Cell.

Abstract

Proton-conducting metal-organic frameworks (MOFs) have attracted attention as potential electrolytes for fuel cells. However, research progress in utilizing MOFs as electrolytes for fuel cells has been limited, mainly due to challenges associated with issues such as the fabrication of MOF membranes, and hydrogen crossover through the MOF's pores. Here, we report proton conductivity and fuel cell performance of a self-standing membrane prepared from of a bismuth subgallateMOF nanosheets with non-porous structure are reported. The fabricated MOF nanosheet membrane with no binding agent exhibitsed structural anisotropy. The proton conductivity in the membrane thickness direction (4.4×10-3 Scm-1 ) at 90°C and RH 100% is observed to be higher than that in the in-plane direction of the membrane (3.3×10-5 Scm-1 ). The open circuit voltage (OCV) of a fuel cell with ≈120µm proton conducting membrane is 1.0V. The non-porous nature of the MOF nanosheets contributes to the relatively high OCV. A fuel cell using ≈40µm membrane as proton conducting electrolyte records a maximum of 25mWcm-2 power density and a maximum of 109mAcm-2 current density with 0.91V OCV at 80°C in humid conditions.