Enhanced adsorption sites in monolayer MoS<inf>2</inf> pyramid structures for highly sensitive and fast hydrogen sensor

Here, we present a highly sensitive and fast hydrogen (H2) sensor for 1% H2, well below the critical limit of explosion ignite in air, in a temperature range of 28–150 °C by using monolayer MoS2 pyramid structures with enhanced adsorption sites. The monolayer MoS2 pyramid structures is synthesized by modified chemical vapor deposition technique and characterized by field emission scanning electron microscopy, Raman, photoluminescence and atomic force microscopy. The highest sensitivity of 69.1% was achieved at a moderate temperature with a response time of 32.9 s for the monolayer MoS2 pyramid structures. At room temperature (RT), the sensor showed a sensitivity of 6% with a faster response of 11.3 s and recovery time of 125.3 s. The availability of favourable adsorption sites on in-plane MoS2 and edges of MoS2 in monolayer MoS2 structures provide enhanced adsorption sites for gas sensing and resulted in the high sensitivity and low response time compared to that of bare MoS2 and other nanostructures-based H2 sensor. The detailed gas sensing mechanism is proposed in the light of detail surface morphology and density function theory (DFT). This study reveals that tailoring the favourable adsorption sites in 2D materials is helpful to develop the highly sensitive and fast H2 sensor for next generation safety devices for H2 fueled vehicle and clean energy applications.