Hydrothermal synthesis and enhanced xylene-sensing properties of pompon-like Cr-doped Co3O4 hierarchical nanostructures

Pompon-like Co3O4 and Cr-doped Co3O4 hierarchical nanostructures were synthesized via a hydrothermal reaction, and a series of different proportions of Cr were doped to investigate the effect of Cr-doping on the gas sensing performance. All the prepared materials were used to fabricate gas sensors, and the result of the gas sensing measurements indicated that the optimum proportion of Cr/Co was 5 at%, whose response (6.38) to xylene (5 ppm) was higher than the others. Further, with increasing Cr ratio, the response to xylene (5 ppm) tended to decline after ascending, with 5 at% (Cr/Co) as the cut-off point, but all sensors made from Cr-doped Co3O4 hierarchical nanostructures showed a higher response to xylene than the pure Co3O4 hierarchical nanostructures, which improved the selectivity of sensors. In addition, it is worth mentioning that all the sensors' optimum working temperatures were low, requiring a smaller heating current and low power consumption.