pH-tuned SnSOx nanostructures for ultralow humidity sensing with high-temperature sensor operation

초록

In this work, pristine SnO2 and pH-tuned SnSOx nanostructures were synthesized via a hydrothermal method. Among the synthesized samples, the pH-3 SnSOx nanostructure exhibited enhanced humidity-sensing performance over a wide humidity range, including ultralow trace-level humidity down to 55.64 ppm, while maintaining stable operation at an elevated sensor temperature of 250°C. The hierarchical interconnected microsphere architecture provides abundant adsorption sites and facilitates effective transport of water molecules. In addition, sulfur-induced defects and oxygen vacancies in the SnO2 framework enhance surface reactivity and promote strong chemisorption. These combined features lead to a humidity-sensing mechanism dominated by modulation of electronic charge carriers through surface redox reactions at elevated temperatures. As a result, the pH-3 SnSOx sensor exhibits a sensitivity of 0.0229 μA/% RH, response and recovery times of 26.1 and 17.9 s, respectively, a hysteresis of ∼1.5%, and stable operation over 30 days. These results demonstrate that pH-tuned SnSOx nanostructures are promising candidates for ultralow-humidity sensing using high-temperature-operated sensors in demanding environments. Copyright © 2026. Published by Elsevier B.V.

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