Hierarchical Co3O4@NiMoO4 core-shell nanowires for chemiresistive sensing of xylene vapor

Hierarchical Co 3 O 4 @NiMoO 4 core-shell nanowires (NWs) were synthesized utilizing a two-step hydrothermal method. The NWs show a high chemiresistive response (at a temperature of 255 °C) to xylene, with an R gas /R air ratio of 24.6 at 100 ppm xylene, while the response towards toluene, benzene, ethanol, and acetone, CO, H 2 S and NO 2 is much weaker. In contrast, pure Co 3 O 4 nanowires exhibit weak responses to all the vapors/gases and poor selectivity. The new NW sensor displays an almost linear response (1–100 ppm) to xylene and a lower detection limit of 424 ppb. The remarkable gas sensing characteristics are attributed to the synergistic catalytic effect and the formation of a heterostructure between Co 3 O 4 and NiMoO 4 . Schematic presentation of a xylene vapor chemiresistive sensor based on Co3O4@NiMoO4 core-shell nanowires. The Co3O4@NiMoO4 core-shell nanowires-based sensor exhibits a high response (24.6) to 100 ppm xylene at 255 °C and high response/recovery speed (13–15 and 25–29 s).