Ultra-high gas sensing properties of porous Cr2O3@SnO2 composite toward NOx based on the p-p heterostructure

Abstract

In recent years, environmental pollution and industrial accidents caused by the leakage of harmful gas are ever-increasing, and advanced gas sensors have been considered to be one of the main strategies for environmental monitoring and industrial safety control. Herein, Cr2O3 film decorated disordered porous SnO2 (Cr2O3@SnO2) composite was synthesized as an effective gas sensor toward NOx gas. The response of the Cr2O3@SnO2 gas sensor toward 100 ppm NOx gas could reach 71 % and the response time is 2.5 s. Meanwhile, the minimum detection level toward NOx gas is only 0.3 ppm, which is pretty lower compared to other materials reported before. The excellent gas-sensitive performance is attributed to the unique heterostructure formed between the Cr2O3 film and the SnO2 matrix, and electrons in this area can migrate to overcome the barrier with less energy. As a result, O2 and NOx gas can draw electrons from the Cr2O3@SnO2 gas sensor easily, thus leading to improved gas-sensitive performance. More importantly, this research provides a new idea to synthesize effective NOx gas-sensitive materials based on the p-p heterostructure.