Hydrothermal synthesis of hierarchical CuBi2O4 microspheres with improved gas sensitivity

Spinel CuBi2O4 microspheres with hierarchical structures in terms of compacted nanoblocks and radial nanorods were prepared by a facile hydrothermal process without additives. The diameters of CuBi2O4 microspheres were modulated in the range of 9.1-15.3 mu m, while the nanoblocks and nanorods were self-assembled with increased cross-sections by extending reaction time. XRD and XPS analysis confirmed the preferable crystallization and high purity in all types of CuBi2O4. N2 adsorption and desorption determinations revealed a maximum specific surface area of 6.0512 m2g-1. The optimal sensitivity responses occurred around 240 degrees C as the as-prepared CuBi2O4 were made into gas sensors, where formaldehyde, methanol, ethanol and ammonia were selected as tested gases. High gas selectivity and sensitivity were revealed in detecting formaldehyde, and superior repro-ducibility was obtained after four consecutive tests. Gas sensing mechanisms were discussed with the emphasis on hierarchical structures of CuBi2O4 microspheres.

Automated summary

In this study, spinel CuBi2O4 microspheres with hierarchical structures were synthesized by a hydrothermal process, and their application in gas sensing was investigated. The experimental results showed that the CuBi2O4 microspheres exhibited excellent crystallinity and high purity, and demonstrated high sensitivity and gas selectivity in formaldehyde detection.