Room temperature hydrogen sensing of multiple networked ZnO/WO3 core–shell nanowire sensors under UV illumination

ZnO/WO3 core–shell nanowires were synthesized by thermal evaporation of a mixture of ZnO and graphite powders (ZnO:C = 1:1) followed by sputter-deposition of WO3. The sensing properties of multiple networked ZnO-core/WO3-shell nanorod sensors toward H2 gas was examined. The responses of pristine ZnO and ZnO-core/WO3-shell nanorods to 1000 ppm H2 at room temperature under UV illumination were ∼236% and ∼645%, respectively. The responses of the core–shell nanowires increased from ∼118 to ∼645% with increasing the UV illumination intensity from 0 mW/cm2 to 1.2 mW/cm2. The enhanced sensing performance of the ZnO-core/WO3-shell nanowires induced by encapsulation with WO3 was explained based on a combination of surface depletion and potential barrier-controlled carrier transport models. The origin of the enhanced sensing properties of ZnO-core/WO3-shell nanorods toward H2 under UV illumination was also discussed.