Tantalum-Palladium: hysteresis-free optical hydrogen sensor over 7 orders of magnitude in pressure with sub-second response

TL;DR

This paper introduces a hysteresis-free optical hydrogen sensor using thin film Ta$_{1-y}$Pd$_y$ with a wide detection range over seven orders of magnitude, rapid response times, and tunable sensitivity.

Contribution

It demonstrates a novel nanoconfined Ta$_{1-y}$Pd$_y$ film that eliminates hysteresis and allows easy tuning of the sensing range without sensitivity loss.

Findings

Hysteresis-free sensing response due to nanoconfinement.

Wide detection range covering at least seven orders of magnitude.

Sub-second response times at room temperature.

Abstract

Hydrogen detection in a reliable, fast, and cost-effective manner is a prerequisite for the large-scale implementation of hydrogen in a green economy. We present thin film Ta$_{1-y}$Pd$_y$ as effective optical sensing materials with extremely wide sensing ranges covering at least seven orders of magnitude in hydrogen pressure. Nanoconfinement of the Ta$_{1-y}$Pd$_y$ layer suppresses the first-order phase transitions present in bulk and ensures a sensing response free of any hysteresis. Unlike other sensing materials, Ta$_{1-y}$Pd$_y$ features the special property that the sensing range can be easily tuned by varying the Pd concentration without a reduction of the sensitivity of the sensing material. Combined with a suitable capping layer, sub-second response times can be achieved even at room temperature, faster than any other known thin-film hydrogen sensor.