Orbital-Level Chemical Coding for Exclusive Detection of VOCs Gases in Chemiresistive Sensors

Cost-effective chemiresistive gas sensors are widely applicated in the commercial detection of volatile organic compounds (VOCs). However, their poor selectivity towards a target VOC within chemically similar mixtures impedes both qualitative and quantitative accuracy. This arises from the absence of intrinsic chemical criteria for designing selective sensing systems. This research emphasizes the importance of orbital engineering to achieve selectivity in chemiresistive materials. We tailor O 2p-band center (ε_{O‑2 p}) of the model material SnO₂, achieving near 100% selectivity towards triethylamine (C₆H₁₅N) and exceptional selectivity towards formaldehyde (CH₂O), respectively, and maintaining these selectivity performances in gas mixtures. Specifically, tailoring the ε_{O‑2 p} enables energy-level matching between O 2p orbitals and frontier molecular orbitals (FMOs) of distinct VOCs gases, thereby inducing selective orbital hybridizations. Such hybridization drives specific adsorption-reaction processes and provides the electron-transfer channel, ultimately triggering the exclusive electrical response. These findings not only unveil the origin of sensing selectivity but also establish a chemical coding strategy for the rational design of exclusive gas sensors based on an orbital-energy-matching framework.