Quantitative Structure–Activity Relationship of Nanowire Adsorption to SO₂ Revealed by <i>In Situ</i> TEM Technique

Abstract

A quantitative structure-activity relationship (QSAR) is revealed based on the real-time sulfurization processes of ZnO nanowires observed via gas-cell <i>in situ</i> transmission electron microscopy (<i>in situ</i> TEM). According to the <i>in situ</i> TEM observations, the ZnO nanowires with a diameter of 100 nm (ZnO-100 nm) gradually transform into a core-shell nanostructure under SO₂ atmosphere, and the shell formation kinetics are quantitatively determined. However, only sparse nanoparticles can be observed on the surface of the ZnO-500 nm sample, which implies a weak solid-gas interaction between SO₂ and ZnO-500 nm. The QSAR model is verified with heat of adsorption (-Δ<i>H</i>°) and aberration-corrected TEM characterization. With the guidance of the QSAR model, the following adsorbing/sensing applications of ZnO nanomaterials are explored: (i) breakthrough experiment demonstrates the application potential of the ZnO-100 nm sample for SO₂ capture/storage; (ii) the ZnO-500 nm sample features good reversibility (RSD = 1.5%, <i>n</i> = 3) for SO₂ sensing, and the detection limit reaches 70 ppb.