Promoted room temperature NH gas sensitivity using interstitial Na dopant and structure distortion in FeNiWO.

The demand for gas-sensing operations with lower electrical power and guaranteed sensitivity has increased over the decades due to worsening indoor air pollution. In this report, we develop room-temperature operational NH gas-sensing materials, which are activated through electron doping and crystal structure distortion effect in FeNiWO. The base material, synthesized through solid-state synthesis, involves Fe cations substitutionally located at the Ni sites of the NiWO crystal structure and shows no gas-sensing response at room temperature. However, doping Na into the interstitial sites of FeNiWO activates gas adsorption on the surface via electron donation to the cations. Additionally, the hydrothermal method used to achieve a more than 70-fold increase in the surface area of structure-distorted Na-doped FeNiWO powder significantly enhances gas sensitivity, resulting in a 4-times increase in NH gas response (R/R). Photoluminescence and XPS results indicate negligible oxygen vacancies, demonstrating that cation contributions are crucial for gas-sensing activities in Na-doped FeNiWO. This suggests the potential for modulating gas sensitivity through carrier concentration and crystal structure distortion. These findings can be applied to the development of room-temperature operational gas-sensing materials based on the cations.