Synthesis of Numerous Edge Sites in MoS₂ via SiO₂ Nanorods Platform for Highly Sensitive Gas Sensor

The utilization of edge sites in two-dimensional materials including transition-metal dichalcogenides (TMDs) is an effective strategy to realize high-performance gas sensors because of their high catalytic activity. Herein, we demonstrate a facile strategy to synthesize the numerous edge sites of vertically aligned MoS₂ and larger surface area via SiO₂ nanorod (NRs) platforms for highly sensitive NO₂ gas sensor. The SiO₂ NRs encapsulated by MoS₂ film with numerous edge sites and partially vertical-aligned regions synthesized using simple thermolysis process of [(NH₄)₂MoS₄]. Especially, the vertically aligned MoS₂ prepared on 500 nm thick SiO₂ NRs (500MoS₂) shows approximately 90 times higher gas-sensing response to 50 ppm NO₂ at room temperature than the MoS₂ film prepared on flat SiO₂, and the theoretical detection limit is as low as 2.3 ppb. Additionally, it shows reliable operation with reversible response to NO₂ gas without degradation at an operating temperature of 100 °C. The use of the proposed facile approach to synthesize vertically aligned TMDs using nanostructured platform can be extended for various TMD-based devices including sensors, water splitting catalysts, and batteries.