Process Regulation And Hydrogen Sensing Properties Of Pd Nano-ring/TiO₂ Nanotube Composite Structures

With the air pollution serious,the fossil energy reducing,hydrogen as a kind of new energy,will play an increasing important role in the future life.However,when hydrogen content in air ranges from 4%to 74.2%,and if there is fire in the atmosphere,it will explode easily.In order to ensure the security of the hydrogen in the process of utilization and storage,it is necessary for us to research the hydrogen sensor with high sensitivity and reproducibility.In our work,we fabricated the titania nanotubes?TNTs?by anodic oxidation at different electrolyte temperature?0?-80??.We analyzed the the effects of the electrolyte temperature on the morphology of the TNTs.We also studied the effects of the electrolyte temperature on the performance of the hydrogen sensor,which is based on Pd nano-rings supported by the TNTs.It was found that when the temperature of the electrolyte was at 30?,the TNTs had the most regular form,and the hydrogen sensor had excellent performance.It presented a high sensitivity at 1.9%hydrogen concentration.Hydrogen sensor based on Pd nano-rings supported by TNTs has been investigated at different electrolyte temperature.The temperature varied from 0?to80?,which affected the morphology of the TNTs and the sensitivity of the hydrogen sensor.When the TNTs was prepared at 30?,it had the most regular nanotube structure,and presented a high sensitivity of 97.49%at 1.9vol%hydrogen concentration.Next,we combined the structure of TiO₂ nanotubes with our proposed‘Break-Junction'effect and explained the experimental results.At present,there is no report on the hydrogen sensor based on titanium wire for the preparation of TiO₂ nanotubes.In this dissertation,the structure of TiO₂ nanotubes prepared on titanium wire substrate will be studied based on the water content of the electrolyte.It was found that when the mass fraction of water in the electrolyte is7.5wt%,the hydrogen sensor has the best performance,and the sensitivity of the hydrogen sensor is 94.8%when the hydrogen concentration is 1.9vol%.There are many factors that affect the structure of TNTs,such as anodizing voltage,anodizing time,electrolyte composition,electrolyte temperature,etc.In addition,we used Ag nanoparticles to modify the hydrogen sensor of the Pd nanoparticle/TiO₂nanotube composite structure.We took the catalytic action of Ag as a breakthrough,and explored the effect of Ag nanoparticle modification on the sensitivity of the hydrogen sensor.It has been proved that Ag nanoparticles with thick sputtered thickness are not conducive to obtaining hydrogen sensors with higher sensitivity and shorter response time.