Co-modification of ZnO and Pt nanoparticles on porous nanorod-assembled SnO2 hierarchical structure for highly sensitive and selective detection of sub-ppm-level NO2

Herein, we propose a ZnO and Pt co-modification strategy to boost the NO 2 sensing performance of SnO 2 . Specifically, a ternary Pt/ZnO/SnO 2 composite was prepared by sequentially decorating ZnO and Pt nanoparticles onto a porous nanorod-assembled hierarchical structure (PNRHS) of SnO 2 . The resulting Pt/ZnO/SnO 2 composites were characterized using various techniques, and their sensing properties to NO 2 were investigated. The results reveal that after co-modification with ZnO and Pt, the SnO 2 sensor exhibits remarkable performance enhancements in detecting sub-ppm-level NO 2 , including significantly improved sensitivity, superior gas discrimination capability, and accelerated response kinetics. At its optimal working temperature of 140 °C, the optimized Pt/ZnO/SnO 2 sensor demonstrates a response of 105.6–1 ppm NO 2 , approximately 42.2, 7.4, and 7.9 times than that of the pure SnO 2 (2.5 at 120 °C), ZnO/SnO 2 (14.3 at 150 °C), and Pt/SnO 2 (13.3 at 140 °C) sensors, respectively. The enhanced NO 2 sensitivity of the ternary Pt/ZnO/SnO 2 composite sensor is attributed to the synergistic sensitization effects of the ZnO and Pt modifiers, whose underlying mechanisms are discussed.