(Invited) Role of Surface p-n Heterojunctions in the Gas Sensing with Smox Based Devices - Operando Studies Insights

摘要

Resistive gas sensors based on semiconducting metal oxides (SMOX), such as SnO_2, WO_3 and In_2O_3, are widely applied for the detection of flammable or toxic gases such as hydrogen, methane or carbon monoxide. Because of their good sensitivity and stability, simplicity of use, low power consumption, ease of integration and low cost they are also obvious candidates to provide the IoT with the sense of smell. In their pristine form they have, however, inherent disadvantages such as strong interference with water vapour and poor stability. To overcome them, the semiconducting oxides are loaded with catalytically active metals, such as Pd, Pt, Rh or Au; this procedure is often referred to as doping. The understanding of the way in which these additives are impacting the sensor performance is crucial for the further improvement. The models that are generally used were established more than 25 years ago and are not in line with the wealth of new information acquired by applying the newest investigation approaches.