PdRh-functionalized porous In2O3 films to boost NO2 detection at room temperature and mechanistic insights by DFT

To achieve high and fast response at room temperature (RT) has long been a challenge for metal oxide semiconductors (MOS) sensors. Compared to single-metal functionalization, dual-metal modification of MOS offers a viable avenue to high-performance RT sensors. Herein, we employ atomic layer deposition (ALD) technology to deposit Pd and Rh metals on porous In2O3 thin films and investigate their sensitization effects on the NO2 sensing properties. Notably, the Pd/Rh catalysts enable the In2O3 sensor to have a remarkable 13-fold response (31.2) to 10 ppm NO2 at RT compared to that (2.4) of pure In2O3, which is superior to those reported In2O3-based sensors. Meanwhile, the In2O3/Pd/Rh sensor has a very fast response speed of 6.6 s and a low detection limit of 62 ppb. Density functional theory (DFT) calculations reveal that the Pd/Rh catalysts dramatically improve the interaction and charge transfer between NO2 and In2O3. This work will further promote the exploration of RT sensor sensitization strategy.