Layer-selective hydrogenation and proton transport in twisted bilayer graphene

TL;DR

This paper demonstrates layer-specific electronic phase transitions and proton transport in twisted bilayer graphene, enabling configurable logic gates through electrochemical control of hydrogenation.

Contribution

It introduces a novel method for layer-selective hydrogenation and proton transport in twisted bilayer graphene driven by electric fields and charge imbalance.

Findings

Layer-selective conductor-insulator transitions achieved.

Proton transport enabled through the bilayer.

Multiple configurable logic gates demonstrated.

Abstract

Recent work investigated graphene's hydrogenation with independent control of the electric field, E, and charge density, n, in the crystal and showed that the process is controlled by n. Here, we demonstrate layer-selective conductor-insulator transitions in twisted bilayer graphene, driven by hydrogenation at fixed n under strong E. This process is accompanied by proton transport through the bilayer, enabling several parallel and configurable logic gates in the devices. Selectivity arises because the large twist angle decouples the two layers' electronic systems, enabling independent control of their charge densities. Polarisation by the field then induces a charge imbalance at fixed total n, triggering hydrogenation when one of the layers' charge densities reaches the threshold for monolayer hydrogenation. Our results introduce a new type of electrode-electrolyte interface in which electrochemical processes are controlled with two decoupled 2D electron gases, opening new design opportunities for energy and information processing devices.