Comment on "Understanding the Increasing Trend of Sensor Signal with Decreasing Oxygen Partial Pressure by a Sensing-Reaction Model Based on O 2- Species"

In the original paper, Zhao and co-workers describe a sensing model to explain the response to a reducing gas as a function of the oxygen partial pressure. In this Comment we specifically analyze the basic gas detection mechanisms proposed in such a work and expressed through surface reactions (eqs 1-5). The consequence of these presented mechanisms lead to inconsistencies that are also regularly found in the literature.