# Boosting Bulk‐to‐Surface Electron Transfer in CeO2 via Oxygen Vacancy Channels for Ultrafast NO2 Sensing

## TL;DR

Researchers improved electron transfer in CeO2 to enable ultra-fast detection of NO2 at room temperature.

## Contribution

A novel strategy to form electron transfer channels in CeO2 via oxygen vacancy migration for enhanced gas sensing.

## Key findings

- Electron transfer channels in CeO2 improve surface electron concentration and reaction activity.
- The sensor detects 20 ppb NO2 within 5 seconds at room temperature.
- The strategy resolves the kinetic contradiction between bulk electron transport and surface reactions.

## Abstract

Modulating the electron transport dynamics in gas sensors is crucial for achieving rapid‐response gas detection. However, polaron localization causes sluggish electron migration from the bulk to the surface, severely limiting surface electron concentration and reaction activity. In this work, we leverage the difference in migration barriers of surface Vo in CeO2 to drive the directional migration of surface Vo into the bulk via precisely controlled thermal treatment, thereby forming electron transfer channels bridging the bulk and the surface. Experiment result confirm that the formation of electron channels enhances electron transfer efficiency from bulk to surface, leading to a dual improvement in both electron concentration and reaction activity at surface Vo sites, which further promotes the adsorption and activation of O2 and NO2. Enabled by this strategy, CeO2 achieves long‐term stability and new benchmark for ultra‐fast detection of 20 ppb NO2 in 5 s at room temperature. This work provides a new strategy to resolve the kinetic contradiction between bulk electron transport and surface reactions.

The formation of electron transport channels overcomes the sluggish electron migration caused by polaron localization, significantly enhancing surface electron concentration and reaction activity, thereby promoting the adsorption and activation of O2 and NO2. Enabled by this strategy, the CeO2‐based sensor achieves ultra‐fast detection of 20 ppb NO2 within 5 s at room temperature.