Gas sensor towards n-butanol at low temperature detection: hierarchical flower-like Ni-doped Co3O4 based on solvent-dependent synthesis

Abstract In this work, hierarchical flower-like Ni-doped Co3O4 was synthesized via a facile one-step coprecipitation method. In the synthesis process, a series of solvent-dependent experiments were carried out to investigate the effect of ethanol/water ratio (R-E/W) on samples. With the increasing ethanol/water ratio, the doping concentration of Ni2+ increased and the microstructure evolved from micro-leaves to micro-flowers. Additionally, gas sensors based on prepared materials were fabricated to evaluate their gas sensing properties. The comparative analysis illustrated that the sensor based on 5.3 mol% Ni-doped Co3O4 microflowers (R-E/W = 3/30) presented the highest response (8.34) to 100 ppm n-butanol at low optimum temperature (165 °C), with a response/recovery time of 59/63 s, and it also exhibited excellent anti-humidity properties and long-term stability. The unique hierarchical flower-like microstructure and the optimized parameters (catalytic sites, carrier concentration, ratio of Co2+, oxygen component) caused by the doping of Ni were responsible for the improved gas sensing performance. Therefore, this work presented a simple solvent-dependent route to controllably synthesize Ni-doped Co3O4 sensing material, and the excellent gas sensing properties of the sensor based on 5.3 mol% Ni-doped Co3O4 microflowers revealed a great application prospect in detecting n-butanol.