Study On Controllable Carbon Doping And Sensing Properties Of Boron Nitride Nanotubes

Boron nitride(BN),as a novel nanomaterial with excellent properties,has become one of the most important materials studied today due to its strong oxidation resistance,stable chemical properties and outstanding mechanical properties.The tube itself has a wide band gap and poor conductivity,which limits its application in electronic devices.Humidity sensors and gas sensors are an important part of our lives and have been widely used in industry,agriculture,food processing,and environmental testing.In order to broaden the scope of application of BNNT,this paper uses BNNT as the basic research object,dynamically controls the conductivity of BNNT by doping with carbon,and studies the humidity sensitivity of BNNT composite membrane and the humidity and gas sensitivity of BCNT membrane,characteristic.High-purity intrinsic BNNT was prepared by ball milling annealing method,and it was composited with conductive polymer PEDOT:PSS to form a composite membrane.The BNNT composite membrane was mounted on a sensing electrode to make a humidity sensor,and the humidity sensitivity characteristics were tested and studied.The effect of acid treatment on the sensor performance.The results show that the sensor has good linearity,repeatability,high sensitivity,and its response time and recovery time are 32s and 22s,respectively.Acid treatment can increase the sensitivity of the sensor,but it will increase the response recovery time.The influence of the ratio of the BNNT and PEDOT:PSS on the performance of the sensor was further studied.It was found that increasing the proportion of the BNNT in the composite film can increase the sensitivity of the sensor and the response recovery time.Finally,the moisture sensitivity of BNNT and CNT sensors was compared.The results showed that the sensitivity of BNNT sensors was higher.The project explored a new method to synthesize BCNNT with simple oper ation and high yield.The bubble method can achieve different concentrations of carbon-doping by changing the bubble time and gas flow rate.Through the semi conductor tester test,it was found that by increasing the amount of carbon in th e BNNT,the conductivity of the BCNNT can be improved to have good semico nductor properties;the prepared BCNNT film was mounted on the interdigitated electrode to make a sensor,and its moisture sensitivity was tested.The character istics and gas sensitivity characteristics and humidity sensitivity results showed th at the BCNNT film has good moisture sensing performance.The influence of th e test frequency on the sensor performance was further studied.It was found tha t the resistance of the sensor decreases with the increase of the test frequency;t he gas sensitivity test is different.Concentrations of ethanol,methanol,toluene,a nd formaldehyde were performed in the gas.The sensor's gas sensitivity characte ristics,the effect of the test frequency on the output resistance of the sensor,an d the stability of the sensor were investigated.The experimental results show tha t the sensor has high sensitivity to ethanol,methanol,and formaldehyde gas.The good stability and the resistance of the sensor decrease with the increasing of t he test frequency.The sensor is insensitive to toluene gas.Finally,the gas select ivity of the sensor is studied.It is found that the BCNNT thin film sensor has higher selectivity to formaldehyde gas.