Effects Of Noble Metal Modification And Heterostructure Construction On Gas Sensitivity Of MoO₃

With the improvement of living standards and the development of science and technology,people’s awareness of safety and health is becoming stronger and stronger,and the demand for detection of gas composition and concentration in the living environment is increasing.Therefore,the requirements for gas sensors and gas detection technology are becoming higher and higher.Improving the gas sensitive performance of gas sensors is the only way to cope with the increasingly complex application environment and higher performance requirements.MoO₃ is a wide band gap semiconductor,which has a wide application prospect in the field of gas sensors due to its unique structure and stable properties.Some studies have confirmed the feasibility of MoO₃ as a basic material for gas sensors,but its gas-sensitive performance still needs to be further improved before practical application.In this paper,MoO₃ with low dimensional structure was synthesized by hydrothermal method,and its gas sensitive properties were modified by noble metal modification and heterostructure construction strategy in view of its existing problems as a gas sensitive material.MoO₃ with nanoribbon structure was prepared by hydrothermal method.MoO₃was modified by doping Au with different concentrations.Through morphology and structure testing,it was found that Au was attached to the surface of MoO₃ nanoribbon in the form of nanoparticles,with the particle size less than 10 nm.Gas sensitive performance test results show that MoO₃ sample has the best response to ethanol gas when Au doping concentration is 3 at.%,and the response to 100 PPM ethanol reaches38,5 times that of pure MoO₃.The sensor has good repeatability,and can output response stably with very little buoyancy.On the basis of Au modification,Au-Pt and Au-Ru bimetallic catalysts have been modified on MoO₃ nanobands.Au-pt bimetal modification improves the selectivity of the sensor,but with the increase of Pt doping concentration,the response of the sensor decreases.After Au-Ru bimetal doping,MoO₃ nanoribbons show better gas sensitivity than Au single metal modification.When Au doping concentration is 3 at.%and Ru doping concentration is 2 at.%,the sensor has 107 response to 100 ppm ethanol at175℃,and the selectivity is greatly improved.The detection limit is as low as 27 ppb,which provides new possibilities for detection of ethanol at very low concentrations.Mo S₂-MoO₃ heterostructure complex was constructed by a simple method of partial oxidation after vulcanization.Compared with pure MoO₃ nanoribbons,the response of the composite to 100 ppm ethanol reaches 12 at 140℃,the response and selectivity of the material are improved,and the optimal operating temperature is greatly reduced.It is found that the composite Mo S₂ reduces the resistance of the material,and reduces the detection difficulty and energy consumption in testing and application.