A comprehensive comparison study on magnetic behaviour, defects-related emission and Ni substitution to clarify the origin of enhanced acetone detection capabilities

Abstract

• Pure and Ni substituted ZnFe 2 O 4 were produced via microwave-assisted hydrothermal method. • Ni substitution influenced structural, magnetic and sensing properties. • The Ni substituted ZnFe 2 O 4 NPs based sensor demonstrated the highest gas-sensing capabilities. In this work, nickel (Ni) substituted zinc ferrite nanoparticles (NPs) with formula N i x Z n 1 - x F e 2 O 4 ( x = 0 , 0.1 , 0.3 , 0.4 ) were synthesized using a microwave-assisted hydrothermal method. We further evaluated the effects of Ni substitution on structural, defects, magnetic and gas sensing properties of the pure ZnFe 2 O 4 arising from the nickel substitution. The gas sensing findings revealed that the sensor based on 0.1 Ni substituted ZnFe 2 O 4 displayed a high response of 34.5–40 ppm of acetone at an optimal working temperature of 120 °C. All sensors demonstrated an excellent response towards acetone and remarkable selectivity against NO 2 , NH 3 , CH 4 , and CO with the sensor based on Ni 0.1 Zn 0.9 Fe 2 O 4 displaying the best response as compared to the rest. The enhanced sensing capability of the Ni 0.1 Zn 0.9 Fe 2 O 4 based sensor stems from combined effects of high concentration of surface defects and F e 2 + cations in the octahedral sites which promoted greater adsorption of oxygen species and adsorption capacity. The gas sensing mechanism of the Ni 0.1 Zn 0.9 Fe 2 O 4 sensor was therefore explained in consideration of a higher surface reaction which occurs at its surface due to higher adsorbed oxygen molecules serving as direct adsorption sites for oxygen and acetone.