Amorphous Pt-Decorated\nNiFe<sub>2</sub>O<sub>4</sub> Nanorods for Acetone Sensing

The decoration of less agglomerated hierarchical semiconducting\nmetal oxides with noble metals is a widely used strategy to obtain\nhigh-performance gas sensors. Beyond conventional approaches, we synthesized\namorphous Pt-decorated NiFe<sub>2</sub>O<sub>4</sub> nanorods as sensing\nmaterials by using a temperature-controlled one-step impregnation\nmethod. This method is characterized by its simplicity and green,\nenergy-efficient, and economical use of noble metals. The Pt-decorated\nNiFe<sub>2</sub>O<sub>4</sub> nanorods show unusual resistance behavior\nin air, and their operating temperature–resistance curve exhibits\ntwo transitions. This phenomenon results from the enhanced chemisorption\nof oxygen molecules compared to pristine NiFe<sub>2</sub>O<sub>4</sub>, which was proven by the operating temperature-dependent resistance\nbehavior in N<sub>2</sub>. The synergistic effects between the amorphous\nnoble metal and less agglomerated structure lead to significantly\nimproved sensing performance to acetone, especially the 5 wt % Pt-decorated\nNiFe<sub>2</sub>O<sub>4</sub>. It shows a 37-fold increase in gas\nresponse, a lower optimal operating temperature, and enhanced selectivity\ncompared to its counterpart. This research offers an efficient method\nfor designing noble metal-decorated, high-performance metal oxide\nsensing materials and provides insights into the baseline resistance\nof oxygen chemisorption onto the surface sensing materials.