Superiorly sensitive and selective H2 sensor based on p-n heterojunction of WO3–CoO nanohybrids and its sensing mechanism

In this study, an excellent hydrogen gas sensor based on the WO3–CoO nanohybrids (WCNHs) heterojunction structure has been successfully fabricated. The WCNHs device showed superior sensitivity, admirable selectivity as well as excellent long-term stability for target gas. In particular, the considerable gas sensing response of WCNHs (5:4) towards 100 ppm hydrogen gas (H2) concentration was reached 39, which is superior to that of the outstanding candidates. Especially, the detection limit capability was as low as 311 ppb. The remarkable response of WCNHs (5:4) can mainly be ascribed to appropriate morphology characteristics and the promising p-n heterojunction architecture, resulting in efficient absorbing behavior and beneficial charge carrier transportation. As a Result, the aims of improving Ra (intrinsic resistance) and decreasing Rg (test resistance) have been simultaneously achieved ultimately leading to an impressive response value of WCNHs sensing materials. The present results verified that WCNHs heterojunction structure was an outstanding design to enhance the H2 sensing performance for WO3-based gas sensors.