Synergistic Heterojunction and Noble-Metal Sensitization in Ag/In2O3/CuO for Enhanced Triethylamine Sensing with Trace Detection Capability

Abstract Triethylamine (TEA) poses a serious threat to human health, necessitating high-performance gas sensors. This work enhances TEA sensing by co-modifying In2O3 with CuO and Ag. A series of In2O3-based composites (binary In2O3/CuO with different ratios of In to Cu, and ternary Ag/In2O3/CuO with 3–9 wt % Ag) was prepared via solvothermal calcination and chemical reduction. Sensing performance progressively improved from pristine In2O3 to binary and ternary composites. The 7 wt % Ag-loaded In2O3/CuO sensor showed a 46.65-fold higher response to 100 ppm TEA than pristine In2O3. Moreover, the optimal working temperature was reduced by 80 °C and it achieved a ppb-level detection limit. The enhanced performance is attributed to the synergistic effects of p–n heterojunction formation, Ag-induced chemical and electronic sensitization, and oxygen-vacancy regulation. This study provides an effective strategy for developing high-performance metal-oxide-semiconductor gas sensors through the cooperative engineering of heterojunctions and noble-metal sensitization.