Density Functional Theory Study Of Gas?O₂,H₂S? Sensing On Hexagonal WO₃?001?surface

The huge threat to human health and safety caused by gas pollution has caused people to invest a lot of energy and funds in the development of sensors for gas detection,monitoring and early warning.Resistance gas sensors based on metal oxide semiconductors have been widely used in the fields of environmental monitoring,agriculture,biomedicine,and industrial production due to their advantages of easy manufacturing,fast response,low price,and long-term stability.At present,there are still problems of unclear sensing mechanism and insufficient sensor sensitivity in the field of metal oxide sensing.Therefore,developing high-performance sensing materials and exploring the sensing mechanism has always been the pursuit of the sensing field.In this work,based on density functional theory,the O₂ sensing potential of the hexagonal tungsten trioxide?h-WO₃??001?surface and?001?monolayer was studied,and the H₂S sensing mechanism of the Pt deposited h-WO₃?001?surface has been studied in depth.?1?The density functional theory was used to systematically study the O₂ adsorption on hexagonal WO₃?001?surfaces,and the influence of surface oxygen density on oxygen sensing was also explored in depth.The calculation results show that WO-terminated surface has considerable sensitivity to O₂.On the perfect WO-termination surface,the maximum adsorption energy and charge transfer reached 1.65eV and 0.392e,respectively.On the WO-terminated surface with oxygen vacancy,the maximum adsorption energy reaches 7.30eV and the charge transfer reaches 0.466e.On the O-terminated surface,regardless of with or without oxygen vacancies,the adsorption energy and charge transfer are not as significant as on the WO-terminated surface,but effective sensing can still be achieved.The study found that the oxygen sensing ability of WO₃ has a negative correlation with the surface oxygen density.It shows that the adsorption sensing of O₂ on h-WO₃?001?surface still obeys the oxygen density mechanism we found in the CO/h-WO₃?001?surface sensing research.The exposed h-WO₃?001?with the WO-terminated surface can be used as a high-sensitivity sensing material for O₂ detection in a low oxygen concentration environment.In addition,the discovery of barrier-less switching from low oxygen density to high oxygen density provides a profound basic understanding of the functional understanding and potential exploration of WO₃ materials.?2?Using density functional theory to explore the electronic properties and O₂ sensing potential of h-WO₃?001?monolayer.The study found that the h-WO₃?001?monolayer still keeps the bulk n-type semiconductor characteristics?band gap is about 0.39eV?,and has a relatively high carrier mobility(about 886cm²V^-1s^-1),so it is a very promising semiconductor electronic material.On this basis,the adsorption sensing characteristics of O₂ gas and six interference gases?H₂,H₂O,CO,CO₂,CH₄,NH₃?on h-WO₃?001?monolayer were studied.The study found that the h-WO₃ monolayer has ultra-high sensitivity and high selectivity for O₂ sensing.The adsorption energy of O₂ on the h-WO₃ monolayer is as high as 7.67eV,and the charge transfer can reach 0.829e,which are greatly improved compared with the bulk phase.In addition,the single layer has a strong adsorption capacity for O₂.At a distance of5.2?,O₂ can still be adsorbed to the surface to achieve dissociation,and adsorption is a barrier-less process.The results show that the h-WO₃?001?monolayer is a promising ultra-sensitive and highly selective O₂ sensing material.?3?The density functional theory was used to study the growth and clustering of Ptn?n=1-5?on h-WO₃?001?O-terminated surfaces with and without oxygen vacancies,and explored the mechanism of improving the H₂S sensing capability.Studies have shown that compared with the O-terminated surface with oxygen vacancies,the adsorption energy of Pt deposition on the O-terminated surface is greater and the adsorption is more stable.The presence of oxygen vacancies is not conducive to the deposition of Pt.Pt deposition can clearly mention the H₂S sensing ability of h-WO₃ surface.The strong H₂S sensing ability of h-WO₃ surface comes from the strong oxidation ability of Pt cluster to H₂S.The electrons are transferred from the H₂S molecules to the Pt cluster,and a large amount of charge is formed,thereby achieving efficient sensing.The presence of Pt clusters on the h-WO₃?001?surface has the potential for efficient catalysis of H₂S sensing.