TiO₂/InVO₄n–n heterojunctions for efficient ammonia gas detection and their sensing mechanisms

In this paper, TiO₂/InVO₄n–n nanoheterojunctions with enhanced gas sensing performance were successfully synthesized. The TiO₂/InVO₄-based sensor exhibits relatively low optimum operating temperature of 250 °C, at which the sensitivity and response/recovery time are 30.5 and 10/10 s, respectively, to 100 ppm ammonia gas. The effective detection (R_a/R_g = 1.7) to 1 ppm ammonia signifies the low detection limit of the sensor. Moreover, the sensor possesses evident room temperature response (R_a/R_g = 3.0, 100 ppm) to ammonia gas. Based on these, the enhanced sensing mechanisms of TiO₂/InVO₄ have been discussed in-depth, which can be ascribed to the synergistic effects of eximious absorption kinetics, outstanding carrier dynamics, unique nanoheterojunction structure and excellent catalytic property. This provides a meaningful guidance for the subsequent nanoheterojunction construction for excellent gas sensor.