Investigation of doped-gadolinium zirconate nanomaterials for high-temperature hydrogen sensor applications

摘要

The incorporation of selective nanomaterials, such as common metal oxide semiconductor compositions, into resistive-type gas sensors has been shown by many researchers to lead to very high sensitivities and response rates, especially for micro-sized chemical sensors for room-temperature applications. The same strategy utilizing sensing nanomaterials has not been demonstrated for hightemperature sensors due to the intrinsic instability of typical metal oxide semiconductor nanomaterials at temperatures[ 500 ℃. Within this work, doped Gd_2Zr_2O_7 (GZO) nanomaterial compositions were investigated for H_2 resistive-type sensors for applications between 600 and 1000 ℃. This paper investigates the mechanism of H_2 sensing for doped GZO nanomaterials and SnO_2/GZO nanocomposites at the elevated temperatures. By integrating 10 vol.% nano-SnO_2 into yttrium-doped GZO nanomaterials, a sensitivity of 4.15 % was retained for 4000 ppm H_2 levels with a low signal drift of 0.42 %/h at 1000 ℃ in a 20 % O_2/N_2 gas stream. The signal drift was reduced by more than half of that compared to pure nano-SnO_2 at the same conditions. The nano-GZO limited the grain growth of the nano-SnO_2 particles and also prevented the nano-SnO_2 from fully reducing to Sn at high temperatures in a low oxygen atmosphere. It is among the first resistive-type sensors operating at 1000 ℃ with sensing times of5 min. This demonstration provided an example of a strategy of combining traditional metal oxide semiconductor and refractory nanomaterial compositions to form sensing nanocomposites with new sensing mechanisms, as well as, enhanced chemical and microstructural stabilities in hightemperature environments.