Modification And Gas Sensing Characteristics Of MoO₃ Nanomaterial

The acceleration of digital and information technology,air pollution,monitoring of poisonous gases in industrial production and gas detection in the micro environment of our daily life are inseparable from gas detection technology.Gas sensors stand out in a variety of gas detection technologies.Because of its unique advantages,gas sensor based on metal oxide semiconductor is the current research hotspot and focus in this field.Molybdenum trioxide?MoO₃?is a typical N-type semiconductor with wide band gap?3.2 eV?.Its unique layered structure and stable physical and chemical properties make it suitable for gas sensing materials.At present,many researches have confirmed the feasibility of MoO₃ as a gas sensor matrix material,but its performance still needs to be improved further.In this paper,a simple solvothermal method was used to prepare MoO₃ sensitive materials with hierarchical structure,and the gas sensitivity of MoO₃sensitive materials was improved by doping metal ions and building heterojunction complex.The specific research contents are as follows:MoO₃ materials with different microstructure were prepared by a simple template free solvothermal method,and modified by doping Ni²⁺with different concentration.Their morphologies and structure were characterized.The results show that the doped material has better dispersion and size homogeneity.Compared with pristine MoO₃,5mol%Ni doped MoO₃ sample has a pompon-like hierarchical structure,with the size of about 200³00 nm.Based on the results of gas sensitivity test,it is found that 5 mol%Ni doped MoO₃ sample has the best xylene response,the response value of 62.6 is 18times of that of pure MoO₃,and the selectivity and response time of xylene are also greatly improved.The change of oxygen composition,specific surface area and crystal size caused by Ni doping may be main reasons for the improvement of sensing performance.The excellent sensing performance of Ni doped MoO₃ makes it a good candidate for xylene sensor.Based on the electronic regulation and catalytic properties of heterojunction,the composite materials with different proportion between MoO₃ and In₂O₃ were successfully prepared by template free hydrothermal method,and the materials were characterized and the corresponding acetone gas sensor was fabricated.The composite with ratio of 1:1 between Mo and In shows a hollow sphere structure with the size of800±50 nm.The surface of the sphere is rough and the specific surface area is large.The sensor based on this sample has a response to acetone of 38.1,far greater than that of pure MoO₃ materials,and much higher than those to other interfering gases.It has excellent cross selectivity,good repeatability and stability.The hierarchical hollow structure introduced by In₂O₃ and the structural characteristics of N-N heterojunctions have greatly improved the gas-sensitive properties of composites.This undoubtedly provides a very feasible scheme for acetone gas sensor.