Band-Engineered Activation of Lattice Oxygen in In₂O₃ via Nitrogen Doping for Advanced Gas Sensing

The reliance of conventional gas sensing on surface-adsorbed oxygen limits both performance and mechanistic understanding. This work breaks from this paradigm by establishing lattice oxygen as an intrinsic reactive species in the sensing process. Herein, we developed a one-step solvothermal synthesis where benzimidazole serves as a dual-function agent: its weak coordination acts as a structural director to steer the formation of a square-shaped In₂O₃ architecture, while its in-situ released nitrogen atoms incorporate into the lattice. This synergistic design not only tailors the electronic structure but, more pivotally, enhances the reactivity of lattice oxygen to promote its efficient participation in gas-sensing reactions. The optimized sensor achieves exceptional ethanol-sensing performance, such as a high response of 715 toward 200 ppm ethanol, representing an 8.5-fold enhancement over pristine In₂O₃, along with fast response/recovery (2 s/24 s), excellent selectivity, and outstanding long-term stability. This work demonstrates that this synergistic doping strategy for enhancing lattice oxygen activity provides a distinct and effective pathway to advanced metal-oxide sensors.