A nanoscale Co3O4–WO3 p–n junction sensor with enhanced acetone responsivity

A nanoscale Co 3 O 4 –WO 3 p–n junction sensor was established here. Via a two-step procedure (hydrothermal reaction/calcination), p-type Co 3 O 4 nanoparticles were decorated on the surface of n-type WO 3 nanorods (NRs). Characterization by SEM, TEM and XRD showed they contact intimately with each other. Via gas sensing test, the Co 3 O 4 –WO 3 sensor displayed two times of response (R a /R g ) than that of pure WO 3 NRs sensor (toward 100 ppm acetone, 280 °C). Moreover, it also had a better selectivity towards acetone than that of pure WO 3 NRs sensor. The mechanism analysis showed that its enhanced sensing performance was due to the extension of depletion layer in the p–n junction.