Singular room-temperature hydrogen sensing characteristics with ultrafast recovery of PtNb2O5 porous composite ceramics

Pt Nb 2 O 5 porous composite ceramics have been prepared from Pt and Nb 2 O 5 particles through convenient pressing and sintering. Extraordinary room-temperature hydrogen sensing capabilities have been revealed for Pt Nb 2 O 5 composite ceramics of 1 wt% Pt, including a sensitivity over 165, response time and recovery time of 7s and 39s, respectively, for 1% H 2 in air. For 0.25% and lower concentrations of H 2 in air, ultrafast recoveries, such as a recovery time of 8s for 0.04% H 2 in air, are observed, which are singular for room-temperature hydrogen sensing. We further found a strong correlation between the resistance of Pt Nb 2 O 5 composite ceramics and hydrogen concentration in ambient oxygen-free atmospheres, and a negative temperature dependence of hydrogen sensitivity, from which a hydrogen sensing mechanism rooted in hydrogen chemisorption on Nb 2 O 5 has been established, while the ultrafast recoveries are explained in terms of a highly mobile and reactive state of chemisorbed hydrogen ions on Nb 2 O 5 .