Promoted room temperature NH3 gas sensitivity using interstitial Na dopant and structure distortion in Fe0.2Ni0.8WO4

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 3 gas-sensing materials, which are activated through electron doping and crystal structure distortion effect in Fe 0.2 Ni 0.8 WO 4 . The base material, synthesized through solid-state synthesis, involves Fe cations substitutionally located at the Ni sites of the NiWO 4 crystal structure and shows no gas-sensing response at room temperature. However, doping Na into the interstitial sites of Fe 0.2 Ni 0.8 WO 4 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 Fe 0.2 Ni 0.8 WO 4 powder significantly enhances gas sensitivity, resulting in a 4-times increase in NH 3 gas response (R g /R a ). Photoluminescence and XPS results indicate negligible oxygen vacancies, demonstrating that cation contributions are crucial for gas-sensing activities in Na-doped Fe 0.2 Ni 0.8 WO 4 . 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.