High Performance Room‐Temperature Acetone Sensors Enabled by Fermi‐Level Engineering in Au‐Decorated n‐Type SnS ₂ Layers

ABSTRACT Non‐invasive monitoring of diabetes through exhaled acetone detection remains a challenging goal, as energy‐demanding metal oxide sensors operate at elevated temperatures (>150°C). Here, we report on a room‐temperature acetone sensor that harnesses interfacial Fermi‐level modulation in gold nanoparticle (Au NP)‐decorated n‐type SnS 2 layers. In contrast with pristine SnS 2 , which exhibits negative sensitivity due to indirect electron generation from acetone adsorption–induced band (E D ), Au NP decoration effectively repositions the Fermi level below the E D . This realignment facilitates direct charge transfer between acetone molecules and the Au NP–SnS 2 interface, yielding a pronounced positive sensing response. The device exhibits excellent sensitivities of 910% at 7 ppm and 344% at 0.5 ppm under zero gate voltage, with additional tunability enabled through electrostatic gating. This study demonstrates a new material‐engineering strategy for achieving low‐power, room‐temperature molecular diagnostics, advancing the integration of breath‐based sensors into future medical and wearable device technologies.