A novel Ba_1.15La_1.85In₂O_7-δ-based amperometric sensor for hydrogen and steam analysis at reduced operating...

Precise monitoring of water vapor and hydrogen in industrial gas streams is critical for the efficiency, safety, and control of processes in chemical synthesis, energy conversion, and fuel cell technologies. Current solid-state electrochemical sensors are often limited by insufficient sensitivity at lower operating temperatures, cross-sensitivity in complex gas mixtures, and material degradation under humid conditions. This work addresses these gaps by introducing a new sensor material that overcomes the stability-selectivity trade-off common to existing devices.

To overcome these challenges, a novel amperometric solid-state sensor was developed. This sensor employs a newly engineered proton-conducting electrolyte, Ba_1.15La_1.85In₂O_7-δ. This complex oxide material was selected for its high proton conductivity at temperatures below 500 °C and its exceptional chemical stability. The fabricated sensor demonstrated a distinct quantitative limiting current response to both H₂ and H₂O, with minimal cross-interference between these species. The sensor exhibited a consistent ability to analyze water vapor across a concentration range of 1.3 to 10.0 vol% in nitrogen and hydrogen from 0.8 to 6.0 vol% in N₂-H₂ mixtures. The key performance metrics included high signal stability, a linear response to target gas concentrations, and relatively fast response and recovery times, confirming its operational robustness for continuous monitoring.

The novelty of this work lies in the first application of a Ba_1.15La_1.85In₂O_7-δ -based electrochemical cell as a dual-function (H₂/H₂O) amperometric sensor validated under industrially relevant conditions (350-450 °C). This finding is significant as it provides a direct pathway for reliable in-situ analysis in complex streams. More broadly, this finding validates the potential shift from conventional single-perovskite electrolytes to new tailored material classes for electrochemical sensing. The results demonstrate that this material class enables a stable, linear, and selective responses, allowing the fabrication of high-performance amperometric-type sensors.