Surface Enhancement Effects of Tiny SnO 2 Nanoparticle Modification on α-Fe 2 O 3 for Room-Temperature NH 3 Sensing.

The development of a gas sensor capable of detecting ammonia with high selectivity and rapid response at room temperature has consistently posed a formidable challenge. To address this issue, the present study utilized a one-step solvothermal method to co-assemble α-Fe 2 O 3 and SnO 2 by evenly covering SnO 2 nanoparticles on the surface of α-Fe 2 O 3 . By controlling the morphology and Fe/Sn mole ratio of the composite, the as-prepared sample exhibits high-performance detection of NH 3 . At room temperature conditions, a gas sensor composed of α-Fe 2 O 3 @3%SnO 2 demonstrates a rapid response time of 14 s and a notable sensitivity of 83.9% when detecting 100 ppm ammonia. Experiments and density functional theory (DFT) calculations suggest that the adsorption capacity of α-Fe 2 O 3 to ammonia is enhanced by the surface effect provided by SnO 2 . Meanwhile, the existence of SnO 2 tailors the pore structure and effective surface area of α-Fe 2 O 3 , creating multiple channels for the diffusion and adsorption of ammonia molecules. Additionally, an N-N heterostructure is formed between α-Fe 2 O 3 and SnO 2 , which enhances the potential energy barrier and improves the ammonia sensing performance. Demonstration experiments have proved that the sensor shows significant advantages over commercial sensors in the process of ammonia detection in agricultural facilities. This work provides new insights into the perspectives on ammonia detection at room temperature.