Amorphous Pt-Decorated NiFe₂O₄ Nanorods for Acetone Sensing

The decoration of less agglomerated hierarchical semiconducting metal oxides with noble metals is a widely used strategy to obtain high-performance gas sensors. Beyond conventional approaches, we synthesized amorphous Pt-decorated NiFe2O4 nanorods as sensing materials by using a temperature-controlled one-step impregnation method. This method is characterized by its simplicity and green, energy-efficient, and economical use of noble metals. The Pt-decorated NiFe2O4 nanorods show unusual resistance behavior in air, and their operating temperature–resistance curve exhibits two transitions. This phenomenon results from the enhanced chemisorption of oxygen molecules compared to pristine NiFe2O4, which was proven by the operating temperature-dependent resistance behavior in N2. The synergistic effects between the amorphous noble metal and less agglomerated structure lead to significantly improved sensing performance to acetone, especially the 5 wt % Pt-decorated NiFe2O4. It shows a 37-fold increase in gas response, a lower optimal operating temperature, and enhanced selectivity compared to its counterpart. This research offers an efficient method for designing noble metal-decorated, high-performance metal oxide sensing materials and provides insights into the baseline resistance of oxygen chemisorption onto the surface sensing materials.