Defect–regulated Yb–doped WO3 nanoparticles for enhanced H2S sensing

Yb–doped WO 3 nanoparticles with Yb doping ratios of 0.3, 0.5, and 0.8 at% were synthesized by a one-step hydrothermal method followed by calcination. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses suggested that Yb incorporation perturbed the WO 3 lattice, thereby modifying the local electronic environment and increasing the proportion of defect–related and chemisorbed oxygen species, while the monoclinic WO 3 phase was preserved after doping. Gas-sensing measurements demonstrated that 0.5 at% Yb–WO 3 exhibited the optimal H 2 S–sensing performance at 200 °C. Compared with pure WO 3 , its response to 10 ppm H 2 S increased from 4.89 to 8.90, with a response time of 5 s, a recovery time of 36 s, and a theoretical limit of detection (LOD) of 1.97 ppb. The optimized sensor also showed good repeatability, high selectivity, acceptable humidity tolerance, and good long-term stability. The enhanced sensing performance was mainly attributed to Yb–induced lattice distortion, local electronic redistribution, and the modulation of defect–related and chemisorbed oxygen species, which together promoted H 2 S adsorption and interfacial redox reaction. In addition, transient sensing features were used for auxiliary quantitative analysis of H 2 S concentration within the calibrated range. These results demonstrate that low-dose Yb doping is an effective strategy for improving the H 2 S–sensing performance of WO 3 –based sensors.