In situ modification of discoid a-Fe2O3 nanostructures with Bi2WO6 for high performance n-butanol sensor

Intentionally constructing n-n or p-n heterojunctions in nanostructured metal oxide semiconductor (MOS) has been verified to be one of efficient strategies to develop MOS-based gas sensors with high performance. Here, we demonstrate an n-n & alpha;-Fe2O3-Bi2WO6 heterojunction strategy to boost the gas sensitivity of & alpha;-Fe2O3 towards n-butanol. To construct & alpha;-Fe2O3-Bi2WO6 heterojunction in & alpha;-Fe2O3, a novel discoid nanostructure (DNS) of & alpha;-Fe2O3 that assembled with crystalline nanoparticles with the size around 20 nm was first prepared via a sol-vothermal method. Then, evenly distributed Bi2WO6 nanoparticles were modified on the & alpha;-Fe2O3 DNSs via a simple hydrothermal method. The finally obtained Bi2WO6@& alpha;-Fe2O3 DNSs were about 60-90 nm in center thickness and 250-300 nm in diameter. When applied in gas sensor for detecting volatile organic compounds (VOCs), the Bi2WO6@& alpha;-Fe2O3 sensor, as compared with the bare & alpha;-Fe2O3 sensor, exhibited impressive en-hancements in n-butanol sensing performance, including higher sensitivity (0.225/ppm vs 0.073/ppm for 10-100 ppm n-butanol), better selectivity (Sn-butanol/Sacetone: 15.2 vs 6.4) and faster response speed (8 s vs 10 s for 50 ppm n-butanol). These improvements were considered to benefit from the sensitization effects of Bi2WO6@& alpha;-Fe2O3 heterojunction, whose mechanism is discussed in detail.

Automated summary

Constructing n-n or p-n heterojunctions in nanostructured metal oxide semiconductor (MOS) is an efficient strategy for developing high-performance MOS-based gas sensors. In this study, an n-n and α-Fe2O3-Bi2WO6 heterojunction strategy was used to enhance the gas sensitivity of α-Fe2O3 towards n-butanol. By preparing a discoid nanostructure (DNS) of α-Fe2O3 and modifying it with evenly distributed Bi2WO6 nanoparticles, the resulting Bi2WO6@α-Fe2O3 DNSs showed improved sensing performance for n-butanol compared to bare α-Fe2O3, including higher sensitivity, better selectivity, and faster response speed.