Abstract:
Graphene oxide (GO) contains randomly distributed nonconductive sp3-C domains with planar acidity, making it simultaneously an electrical insulator and a proton conductor. GO’s ability for in-plane and through-plane cationic transport together with its impermeability to molecular fuels projected them as inexpensive and sustainable membranes for proton exchange membrane fuel cells (PEMFCs). Nevertheless, the room-temperature proton transport in bulk GO is at least an order lower than that of the state of the art Nafion membrane, challenging the construction of a practical energy conversion device with the former. We show that the proton flux in GO along the H-bonded network projected outward of the carbon planes can be significantly amplified by thinning the 2D carbon layer stacking of carbon nanosheets in GO. The noticeably higher room-temperature fuel cell performance metrics of a thin-layer GO proton conductor compared to the commercial Nafion membrane with ∼410 mW/cm2 of peak power at ∼1300 mA/cm2 of peak current demonstrates distinct progress in the sustainable energy landscape.