Pt Nanoparticle-Modified SnO₂–ZnO Core–Shell Nanosheets on Microelectromechanical Systems for Enhanced H₂S Detection

Pt nanoparticle (NP)-modified SnO2–ZnO (SnO2–ZnO–Pt) core–shell nanosheets (NSs) for hydrogen sulfide (H2S) gas sensing were successfully synthesized via atomic layer deposition, hydrothermal method, and magnetron sputtering. More importantly, the SnO2–ZnO–Pt NS sensing materials were synthesized in situ on microelectromechanical system (MEMS) devices, which are expected to be high-performance gas sensors with superior sensitivity, great selectivity, good reproducibility, and low power consumption. To be specific, the SnO2–ZnO–Pt NSs displayed a high sensitivity (Ra/Rg) of 30.43 and an excellent selectivity when detecting 5 ppm H2S at an operating temperature of 375 °C. Their rate of resistance change was 29.43, which was about 24 and 9 times those of the pristine SnO2 NS (∼1.25) and SnO2–ZnO core–shell NS (∼3.43) sensors, respectively. These substantially improved sensing properties could be mainly attributed to the formation of heterojunctions, catalytic sensitization effect, and increased specific surface area of Pt NP modification. Thus, the proposed SnO2–ZnO–Pt NS gas sensors demonstrate great potential as a high-performance sensing material for application in H2S gas sensors.