Facile Fabrication of Room-Temperature Parts-per-Billion-Level Acetone Sensor Driven by In Situ Laser-Induced Oxygen-Vacancy-Rich Cu/Cu ₂ O/CuO Composites

The introduction of oxygen vacancies (OVs) into metal oxide micro/nanostructures significantly enhances both catalytic performance and electrical conductivity, thereby boosting their gas-sensing capabilities. However, conventional approaches for engineering oxygen vacancies typically require specialized equipment (e.g., autoclave reactors) and extreme operational conditions (e.g., high temperature and high vacuum), posing substantial challenges for practical applications. Herein, a novel single-step laser-induced technique is developed for fabricating CuO_<i>x</i>-based room-temperature acetone sensors under ambient conditions. The technique enables mask-free fabrication of tunable sensing films spanning morphologies from porous networks to nanospheres by precisely modulating the film thickness. Furthermore, oxygen-vacancy self-doping is inherently coupled with the micro/nanostructure growth mechanism, bypassing conventional postsynthesis treatments while preserving process simplicity. The as-prepared CuO_<i>x</i> gas sensors with distinct morphologies manifest exceptional room-temperature acetone sensing with a wide response range spanning 0.1-10 ppm. Comparative analysis of nanosphere-based gas sensors conclusively demonstrates that oxygen vacancies constitute a key structural determinant, enabling room-temperature sensing capability in CuO_<i>x</i>-based sensors. Moreover, both gas sensors exhibit outstanding selectivity toward acetone against common interferents (NO₂, H₂, CO₂, and CO) and a low detection limit, highlighting their potential for trace acetone gas detection applications.