High-sensitivity formaldehyde gas sensor based on Ce-doped urchin-like SnO2 nanowires derived from calcination of Sn-MOFs

Abstract

Metal–organic frameworks (MOFs) have attracted widespread attention due to their regular structures, multiple material centers, and various ligands. They are always considered as one kind of ideal templates for developing highly sensitive and selective gas sensors. In this study, the advantages of MOFs with the high specific surface area (71.9891 m²·g⁻¹) and uniform morphology were fully utilized, and urchin-like SnO₂ nanowires were obtained by the hydrothermal method followed by the calcination using Sn-MOFs consisting of the ligand of C₉H₆O₆ (H₃BTC) and Sn/Ce center ions as sacrificial templates. This unique urchin-like nanowire structure facilitated gas diffusion and adsorption, resulting in superior gas sensitivity. A series of Ce-doped SnO₂ nanowires with different doping ratios were synthesized, and their gas sensing properties towards formaldehyde were studied. The resulted Ce-SnO₂ was revealed to have high sensitivity (201.2 at 250 °C), rapid response (4 s), long-term stability, and good repeatability for formaldehyde sensing, and the gas sensing mechanism of Ce-SnO₂ exposed to formaldehyde was also systematically discussed.