Room-Temperature Hydrogen-Sensing Capabilities of Pt-SnO2 and Pt-ZnO Composite Nanoceramics Occur via Two Different Mechanisms.

Ming Liu,Yongming Hu,Pengcheng Li,Wanping Chen,Liang Cheng,Zilong Tang,Yong Huang

doi:10.3390/nano11020504

Ming Liu, Yongming Hu + Show 5 more

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https://doi.org/10.3390/nano11020504

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Abstract

Impressive room-temperature gas-sensing capabilities have been reported for nanomaterials of many metal oxides, including SnO2, ZnO, TiO2, WO3, and Fe2O3, while little attention has been paid to the intrinsic difference among them. Pt-SnO2 and Pt-ZnO composite nanoceramics have been prepared through convenient pressing and sintering. The former shows strong and stable responses to hydrogen in 20% O2-N2 (synthetic air) at room temperature, while the responses to hydrogen in N2 cannot be stabilized in limited times; the latter shows strong and stable responses to hydrogen in N2, while the responses to hydrogen in synthetic air are greatly depressed. Further analyses reveal that for Pt-ZnO, the responses result from the reaction between hydrogen and oxygen chemisorbed on ZnO; while for Pt-SnO2, the responses result from two reactions of hydrogen, one is that with oxygen chemisorbed on SnO2 and the other is hydrogen chemisorption on SnO2. These results reveal two different room-temperature hydrogen-sensing mechanisms among MOXs, which results in highly contrasting room-temperature hydrogen-sensing capabilities attractive for sensing hydrogen in oxygen-contained and oxygen-free environments, separately.

Highlights

Because of their high sensitivity, simple preparation, good stability, low production cost, and controllable morphology, gas sensors based on SnO2 thick films have been successfully commercialized for several decades
A series of sintering temperatures were investigated for both kinds of nanoceramics, and the pellets of Pt-SnO2 sintered at 825 ◦ C in air for 2 h showed the best performance among the Pt-SnO2 nanoceramics, and the Pt-ZnO pellets sintered at 700 ◦ C
1 wt% Pt sintered at 825 ◦ C and (b) Pt-ZnO composite nanoceramics with 1 wt% Pt sintered at 700 ◦ C

Summary

Introduction

Because of their high sensitivity, simple preparation, good stability, low production cost, and controllable morphology, gas sensors based on SnO2 thick films have been successfully commercialized for several decades. They all have to work at elevated temperatures (~500 ◦ C) [1], which leads to increased energy consumption, shortened service life, and increased safety risks [2]. As for the advantages of nano-structured MOXs, their large number of point defects, especially oxygen vacancies, have been found to play a vital role in enhancing their room-temperature gas sensitivities [17,18]

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