Enhanced Room-Temperature Acetone Detection Enabled by Ba- and Pb-Doped SnO ₂ : A Scanning Kelvin Probe Study

Volatile organic compounds (VOCs), particularly acetone (CH 3 COCH 3 ), pose significant risks to human health and industrial safety, necessitating the development of sensitive, reliable, and low-power detection technologies. Conventional analytical methods such as gas chromatography and mass spectrometry offer high accuracy but are limited by high cost, bulky instrumentation, and unsuitability for real-time monitoring. Metal oxide semiconductor (MOS)-based sensors, especially SnO 2, have attracted considerable attention due to their excellent chemical stability, high carrier mobility, and strong surface reactivity. However, their dependence on elevated operating temperatures results in high power consumption and restricts their applicability in portable and wearable systems. In this study, Ba- and Pb-doped SnO 2 thin films were synthesized via a homogeneous precipitation method and investigated for room-temperature acetone detection using the scanning Kelvin probe (SKP) technique. SKP enables noncontact probing of surface work function (ϕ) and contact potential difference (CPD), providing direct insight into gas-induced surface charge transfer processes without external heating. The doped SnO 2 films exhibited significantly enhanced CPD response and acetone adsorption compared to pristine SnO 2, attributed to dopant-induced surface defects and improved charge transfer dynamics. This work demonstrates the effectiveness of dopant engineering combined with SKP as an energy-efficient and highly sensitive approach for room-temperature VOC detection, offering a promising platform for next-generation low-power gas sensing applications.