Selective ion transport of nonlinear resistive switching by hierarchical nanometer-to-angstrom channels for nanofluidic transistors.

Nanoconfined selective ion transport shows promise for achieving biomimetic ion separation and iontronics information transmission. However, exploration of tunable nonlinearity of ion transport is formidable due to the challenge in fabrication of nanochannel devices of exquisite nanoconfined architectures. Here, we report a hierarchical metal-organic framework (MOF)-based nanofluidic device of multiscale heterogeneous channel junctions to achieve unprecedented triode-like nonlinear proton transport, in contrast with diode-like rectifying transport for metal ions. Through experiments and theoretical simulations, we unveil the underlying mechanism for this unique nonlinear proton transport property, i.e., the gating effect from the built-in electric potential across the MOF phase junctions enabled by voltage bias above a threshold. As a proof-of-concept application demonstration, the nanofluidic device exhibits an ionic memory property as a nanofluidic memristor. This finding of proton-specific nonlinear resistive switching and memristive phenomenon can inspire future studies into nanofluidic iontronics and mass transport by rational design of coupled nanometric and angstrom-sized confinement.