MOF-Derived 3D SnO2 Nanosheet-Assembled Clusters for Ultrasensitive Room-Temperature H2S Detection

Room-temperature detection of hydrogen sulfide (H2S) using metal oxide sensors is challenged by sluggish reaction kinetics and severe humidity interference, which limit practical deployment in complex environments. To address these issues, we develop a facile on-chip annealing strategy to fabricate MOF-derived 3D SnO2 nanosheet-assembled cluster gas sensors without any external dopants. The optimized sensor (annealed at 400 °C for 1 h) is systematically characterized by electron microscopy, X-ray photoelectron spectroscopy, and gas-sensing measurements. The sensor delivers outstanding room-temperature performance: a high response of 95.7 toward 30 ppm H2S, a low detection limit of 10 ppb, and an ultrafast response time of 1 s under a wide relative humidity range of 40-80%. Notably, it maintains H2S sensitivity across 20-80% RH and displays a humidity-enhanced response. Mechanistic analysis suggests that the performance arises from the synergy between open porous clusters assembled from interconnected SnO2 nanosheets and surface defect engineering: controlled annealing regulates lattice oxygen vacancies (OV) and chemisorbed oxygen (OC), thereby modulating interfacial redox kinetics. Facet-dependent water dissociation and water-assisted H2S conversion are proposed to contribute to the humidity-enhanced response. This work provides a dopant-free strategy for miniaturized SnO2 gas sensors operating in humid environments.