Hydrogen gas sensing properties of WO3 sputter-deposited thin films enhanced by on-top deposited CuO nanoclusters.

Abstract Magnetron-based gas aggregation cluster source (GAS) was used to prepare high-purity CuO (cupric oxide) nanoclusters on top of sputter-deposited thin film of tungsten trioxide (WO 3). The material was assembled as a conductometric hydrogen gas sensor and its response was tested and evaluated. It is demonstrated that addition of CuO clusters noticeably enhances the sensitivity of the pure WO 3 thin film. With an increasing amount of CuO clusters the sensitivity of CuO/WO 3 system rises further. When CuO clusters form a sufficiently thick and compact layer, the resistance response is reversed. Based on the sensorial behavior, conventional and near-ambient pressure X-Ray photoemission spectroscopies, and resistivity measurements, we propose that the sensing mechanism is based on the formation of nano-sized p - n junctions in between p -type CuO and n -type WO 3. The advantages of the GAS technique for preparing sensorial and/or catalytically active materials are emphasized. Graphical abstract Image 1 Highlights • Magnetron based gas aggregation cluster source was used for making a hydrogen gas sensor. • CuO nanocluster were combined with a WO 3 thin film. • Addition of CuO clusters noticeably enhances the sensitivity in comparison with a pure WO 3 thin film. • Sensing mechanism based on the formation of nano-sized p-n junction is proposed. • No noble metal was needed to enhance the WO 3 response. [ABSTRACT FROM AUTHOR]