Enhanced Selectivity of NiP2-Ni2P Polymorphs for NO2 Gas Sensing
To date, various materials have been widely investigated for developing highly selective and sensitive sensors for NO 2 , a common hazardous gas. However, the associated NO 2 -gas-sensor fabrication methods exhibit several drawbacks, which hinder the development of NO 2 -sensitive gas sensors with excellent selectivity. In this study, NiP 2 -Ni 2 P polymorphs with observable heterointerfaces were prepared using metalloid NiP 2 and metallic Ni 2 P for NO 2 gas sensing, and the characteristics of the synthesized polymorphs were evaluated through X-ray diffraction and energy-dispersive spectrometry. At 160 °C, the fabricated sensor exhibited a response of 1.5%-93.14% for NO 2 gas over a concentration range of 0.5-60 ppm; its response and recovery times were 16 and 55 s, respectively. In addition, the sensor exhibited excellent NO 2 selectivity and long-term stability. Density functional theory calculations revealed the adsorption sites of NO 2 molecules on NiP 2 , and the gas-sensing mechanism was elucidated. The findings of this study establish NiP 2 -Ni 2 P, which is currently employed as an outstanding electrocatalyst for hydrogen evolution, as a potential NO 2 sensor platform with excellent selectivity and efficient recovery characteristics.
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