# Diffusion Dynamics of Volatile Organic Compounds into Integrated Surface-Supported Metal–Organic Frameworks Heterojunctions

## TL;DR

This paper explores how volatile organic compounds diffuse into a type of hybrid material called SURMOFs, which could improve sensing and environmental monitoring technologies.

## Contribution

The study provides new insights into VOC diffusion dynamics in integrated SURMOF heterojunctions using electrical response measurements.

## Key findings

- The diffusion of methanol, ethanol, propanol, and hexane into HKUST-1 SURMOFs was studied using electrical responses.
- Findings align with Gao’s model, revealing diffusivity, permeability, and pore accessibility in thin HKUST-1 films.
- The study advances understanding of molecular transport in monolithically integrated nanoporous materials.

## Abstract

Surface-supported
metal–organic frameworks (SURMOFs) have
emerged as promising hybrid materials across diverse applications,
including gas separation, energy storage, catalysis, and sensing.
These capabilities are primarily associated with their high porosity
and reasonable control over crystallinity. However, the diffusion
of volatile organic compounds (VOCs) in these structures remains poorly
understood, limiting their range in strategic applications. One significant
challenge is developing effective integration approaches that enable
precise control of molecular transport in these structures. In this
work, we investigated the diffusion dynamics of various VOCs (methanol,
ethanol, propanol, and hexane) into two-terminal devices based on
a HKUST-1 thin-film SURMOF, using conventional photolithography and
nanomembrane-origami technology. Systematic electrical responses (DC
and AC) were monitored as precise and tunable tools for VOC differentiation.
Our experimental results align with Gao’s model, offering new
insights into the diffusivity, permeability, pore accessibility, and
intracrystalline diffusion lengths of VOCs within integrated HKUST-1
with thicknesses below 70 nm. These findings represent significant
advances in understanding diffusion processes in monolithically integrated
nanoporous materials, with potential implications for future innovations
in molecular sensing and environmental monitoring technologies.