Pt-Nb₂O₅-SnO₂ Composite Ceramics Competitive for Cost-Effective Room-Temperature Hydrogen Sensing

Abstract Pt-SnO2 binary and Pt-Nb2O5-SnO2 ternary composite ceramics were prepared using SnO2, Nb2O5 and Pt powders through pressing and sintering, separately. For the Pt-SnO2 binary system, samples with 5 wt% Pt typically possess a sensitivity of 145 for 1% H2-20% O2-N2 and a resistance of 3 MΩ at 25 °C in air of 50% relative humidity, which are 5 times and 20 times larger than those of the samples with 1 wt% Pt, respectively. For the Pt-Nb2O5-SnO2 samples with 1 wt% Pt, their sensitivity for 1% H2-20% O2-N2 is 150 and resistance is 7 MΩ, which are comparable to those of Pt-SnO2 samples with 5 wt% Pt, and much larger than those of Pt-SnO2 samples with 1 wt% Pt. These results show that Nb2O5 has profound effects on the room-temperature hydrogen sensing characteristics of Pt-SnO2 binary system through forming Nb2O5-SnO2 heterojunction.