Researchers from The University of Manchester and the University of Warwick finally solved the long-standing puzzle of why graphene is so much more permeable to protons than expected by theory.
A decade ago, scientists at The University of Manchester demonstrated that graphene is permeable to protons, nuclei of hydrogen atoms. The unexpected result started a debate in the community because theory predicted that it would take billions of years for a proton to permeate through graphene’s dense crystalline structure. This had led to suggestions that protons permeate not through the crystal lattice itself, but through the pinholes in its structure.
Now, writing in Nature, a collaboration between the University of Warwick, led by Prof Patrick Unwin, and The University of Manchester, led by Dr. Marcelo Lozada-Hidalgo and Prof Andre Geim, report ultra-high spatial resolution measurements of proton transport through graphene and prove that perfect graphene crystals are permeable to protons. Unexpectedly, protons are strongly accelerated around nanoscale wrinkles and ripples in the crystal.
The discovery has the potential to accelerate the hydrogen economy. Expensive catalysts and membranes, sometimes with significant environmental footprint, currently used to generate and utilize hydrogen could be replaced with more sustainable 2D crystals, reducing carbon emissions, and contributing to Net Zero through the generation of green hydrogen.
The team used a technique known as scanning electrochemical cell microscopy (SECCM) to measure minute proton currents collected from nanometer-sized areas. This allowed the researchers to visualize…