Pd nanoparticles-sensitized hierarchically nanoflower-like SnO2/SnS2 assembled from nanosheets for ultrasensitive hydrogen detection

Controlling the morphology to modify the properties of materials is an effective strategy to enhance the response performance of gas sensing materials. Herein, a three-dimensional (3D) nanoflower-like tin disulfide (SnS 2 ) structure assembled from nanosheets was synthesized. Subsequent annealing treatment partially oxidizes the nanosheets, inducing random stacking of the nanosheets, thereby increasing the structural disorder analogous to opened hair cuticle. This structure was further decorated by zero-dimension (0D) palladium nanoparticles (Pd NPs) to construct 0D-3D hierarchical structure for hydrogen (H 2 ) detecting. The H 2 sensing experiment results showed that optimized Pd/SnO 2 /SnS 2 gas sensor exhibits a high response of 1260% to 1000 H 2 at 275 °C, along with fast response/recovery time of 18/67 s. The gas sensor exhibited a low limit of detection (1.74 ppm). The above sensing performance is attributed to the unique hierarchical assembled nanoflower-like architecture, which was transformed from an initial closed hair-cuticle-like morphology into an open one by annealing. This newly formed open structure, coupled with the composite formation with Pd NPs, collectively facilitates both the carrier charge transfer process and the adsorption/desorption reaction of H 2 . This work demonstrates a promising strategy for developing high-performance H 2 sensors through morphology-engineered and noble metal-functionalized transition metal dichalcogenides.