Document Type

Article

Publication Date

3-30-2026

Department

Department of Chemical Engineering

Abstract

The demand for sub-ppm hydrogen (H) sensing is growing across emerging applications such as environmental monitoring, breath-based disease diagnostics, and early-stage battery failure detection. However, achieving reliable ppb-level detection with chemiresistive metal oxide sensors remains challenging. At trace gas concentrations, resistance modulation is often insufficient, particularly in the absence of noble metal catalysts. Here, we report samarium-doped tin dioxide (Sm-SnO) nanofibers in which electronic trap-state modulation is exploited to enable ultrasensitive hydrogen sensing. The 2 at% Sm-doped SnO nanofibers exhibited markedly enhanced H sensitivity, achieving clear detection down to 25 ppb H at 200 °C, with a theoretical limit of detection of 4.5 ppb, placing this material among the most sensitive noble-metal-free SnO-based H sensors reported to date. Mechanistic investigations through X-ray photoelectron spectroscopy and electron energy loss spectroscopy revealed that Sm doping introduces deep trap states associated with charge-compensating defect complexes. These states reduce free carrier density, increase baseline resistance, and enable trap-assisted charge release during H exposure, thereby amplifying the sensing response. Trap-state engineering via rare-earth doping, exemplified by Sm-SnO, provides an effective pathway for achieving ppb-level hydrogen detection in noble-metal-free chemiresistive sensors.

Publisher's Statement

© 2026 The Authors. Published by American Chemical Society. Publisher’s version of record:  https://doi.org/10.1021/acssensors.5c04957

Publication Title

ACS sensors

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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