Hydrogen Sensors Based on Cobalt-Modified Molybdenum Oxide

Hydrogen (H 2 ) is one of the most promising clean energy sources, and hydrogen leak detection plays a crucial role in ensuring the safe use of hydrogen. In this work, Co-modified porous MoO 3 nanosheets are synthesized using a microwave-assisted hydrothermal method and an in situ reduction method and are fabricated into a high-performance hydrogen gas sensor. The morphology, elemental composition, and valence states of the sensing material are characterized using SEM, BET, and XPS techniques. The sensor exhibits a response of 41.3% to 500 ppm hydrogen at an optimum operating temperature of 220 °C with a response/recovery time of 12/6 s, which is superior to the response value (13.3%) and response/recovery time (17/21 s) of pristine MoO 3 nanosheets. Additionally, the sensor demonstrates excellent repeatability, selectivity, and long-term stability. Density functional theory (DFT) is used to reveal the performance advantages of Co-modified MoO 3 compared with pristine MoO 3 and to explain the mechanism of Co-modified sensitization. This study confirms that Co-modified porous MoO 3 nanosheets are excellent candidates as sensitive materials for efficient hydrogen sensors.