Atomic Two-Dimensional Materials as Solid Proton Conductors: Achieving the Shortest Proton Transfer Distance with High Selectivity for Energy Applications

Solid proton conductors play a crucial role in advancing sustainable energy technologies. Atomic-scale solid proton conductors, only one atom thick, represent the ultimate limit for proton exchange membranes. They offer unique advantages including near-perfect selectivity, precise control over lattice pore size, and the ability to operate under diverse conditions. These features position them as highly promising candidates for next-generation energy applications. Nevertheless, the fundamental mechanism of proton transport through these pristine materials remains a subject of debate, hindering rational material design and limiting the full exploitation of their potential. This article provides a perspective on this emerging field, offering an overview of the unusual proton conductivity, exceptional selectivity, and energy applications of atomic-scale solid proton conductors along with a critical analysis of the contested mechanisms of proton permeation. Particular emphasis is placed on the key discrepancies between the observed phenomenon and the proton transport mechanism.