ZnO QDs sensitized bio-templated In2O3 microtubes for low temperature dependent selective detection of triethylamine and N-butanol

Abstract

Dual-selective gas sensors are highly desirable for developing high-performance, miniaturized, and low-cost sensing devices. Herein, we report a bio-inspired dual-selective gas sensor based on ZnO quantum dot (ZnO QD)-sensitized bio-templated In₂O₃ microtubes (BIN) for low-temperature selective detection of n-butanol and triethylamine (TEA). BIN were synthesized by a facile impregnation and calcination process using waste rose stems as eco-friendly bio-templates, and sol-gel synthesized ZnO QDs were modified on it to obtain the hierarchical porous composites (BIN/ZQ). The composite with 15 wt% ZnO QDs (BIN/ZQ-0.15) exhibited significantly improved sensing properties, and it achieved high response values of 254 to 100 ppm TEA at 100℃ and 108 to 100 ppm n-butanol at 200℃, respectively, demonstrating a dual selectivity with their parts-per-billion (ppb) detection limits and good stability. The study on sensing behavior of the composite sensor to mixed TEA and n-butanol gas proved its ability to detect the concentration of individual gases in their mixture. The enhanced sensing performance was attributed to the synergistic effects of the In₂O₃/ZnO heterojunctions, abundant oxygen vacancies, hierarchical porous structure, combined with the preferential adsorption of TEA and n-butanol molecules on the composite surface, as revealed by density functional theory (DFT) calculations. Molecular dynamics combined with DFT simulations were further employed to study the reason for the dual selectivity of the composite at different temperatures for the first time. This work would inspire strategies for designing gas sensors with dual selectivity, low operational temperatures, and cost-effective fabrication.