Selective Reduction Laser Sintering: A New Strategy for NO ₂ Gas Detection Based on In ₂ O ₃ Nanoparticles

Abstract This study introduces a novel strategy for fabricating flexible nitrogen dioxide (NO ₂ ) gas sensors based on Indium Oxide (In ₂ O ₃ ) nanoparticles (NPs) employing selective reduction laser sintering (SRLS) technology. The SRSL technology utilizes ultraviolet (UV) laser selective reduction sintering to precisely and rapidly create oxygen vacancy (OV) defects in In ₂ O ₃ NPs. These oxygen vacancies (OVs) enhance the active adsorption sites and contribute additional free electrons, significantly improving sensor performance at room temperature. The sensors demonstrate excellent response ( S = 460.9 at 10 ppm), rapid response/recovery times ( τ _resp / τ _reco = 27/570 s), and superior selectivity (response ratio > 400), in addition to robust resistance to light and humidity (under ppm‐level NO ₂ gas). The sensors also exhibit a low detection limit (200 ppb), a high signal‐to‐noise ratio (94.8 dB), and good long‐term stability (25 days). Moreover, under photo‐assisted conditions, the recovery speed of the sensors is further improved. This technology not only provides an innovative strategy for the development of high‐performance flexible NO ₂ gas sensors but also broadens the application potential of laser direct writing (LDW) technology in advanced materials and sensor fabrications.