High proton conductivity through angstrom-porous titania

TL;DR

This study demonstrates that vacancy-rich titania monolayers exhibit exceptionally high proton conductivity exceeding 100 S/cm² at 200°C, making them promising for hydrogen technology membranes due to their selectivity and permeability.

Contribution

The paper introduces vacancy-rich titania monolayers as highly permeable and selective proton conductors, surpassing previous 2D materials in conductivity and demonstrating practical potential.

Findings

Proton conductivity exceeds 100 S/cm² at 200°C.

Titania monolayers are impermeable to helium.

High vacancy density enables angstrom-scale sieving.

Abstract

Two dimensional (2D) crystals have attracted strong interest as a new class of proton conducting materials that can block atoms, molecules and ions while allowing proton transport through the atomically thin basal planes. Although 2D materials exhibit this perfect selectivity, the reported proton conductivities have been relatively low. Here we show that vacancy-rich titania monolayers are highly permeable to protons while remaining impermeable to helium with proton conductivity exceeding 100 S cm-2 at 200 C and surpassing targets set by industry roadmaps. The fast and selective proton transport is attributed to an extremely high density of titanium-atom vacancies (one per square nm), which effectively turns titania monolayers into angstrom-scale sieves. Our findings highlight the potential of 2D oxides as membrane materials for hydrogen-based technologies.