Sulfate-modified BiFeO3 nanostructure for high-response H2S chemiresistive sensing

Abstract

Sulfate-engineered bismuth ferrite nanostructures (BiFeO₃–S_x, x = 10, 15, and 20%) were fabricated via a glycine-assisted sol–gel combustion route and systematically evaluated as chemiresistive sensors for hydrogen sulfide (H₂S) detection. Structural and spectroscopic characterization confirmed the presence of sulfate species in all modified samples; BiFeO₃–S₁₅ retained the single-phase rhombohedral structure, whereas secondary phases were detected at 10 and 20% sulfate. Among the compositions studied, BiFeO₃–S₁₅ displayed the most favorable textural properties, combining a larger specific surface area with a well-developed porous morphology, as verified by BET and AFM analyses. At an optimized operating temperature of 200 °C, BiFeO₃–S₁₅ achieved a peak sensing response of 98 toward 60 ppm H₂S, substantially outperforming both pristine BiFeO₃ and the other sulfate-modified samples. The optimized sensor further exhibited rapid, reversible response–recovery kinetics, robust repeatability, and pronounced selectivity over interfering gases, including NO₂, SO₂, CO, and NO, at equivalent concentrations, while retaining stable output over a 14-day continuous monitoring period. Collectively, these findings establish sulfate modification as an effective route to enhancing the gas-sensing performance of BiFeO₃-based perovskites, underscoring their promise for real-time air-quality monitoring and environmental pollution control.