WO₃Nanostructure: Preparation With Block Copolymer Template And Hydrogen Sensitivity Properties

Hydrogen has been the most potential energy source in the future, especiallyunder the background of energy crisis. But given the characteristic of be unstable andexplosive, there is still so much limitation to hydrogen widespread application. Toavoid with these tragedy such as explosion, hydrogen sensors could be used to giveprediction of gas leak effectively. As the core of hydrogen sensor device, hydrogensensitivity material is significant to its performance. The metal-oxide semiconductorsuch as WO₃has excellent hydrogen sensitivity performance which includes goodsensitivity and circling stability, also have attracted great attentions. But the WO₃synthesized through traditional methods still have great shortages: on one side, it ishard to get WO₃with highly ordered nanostructures and regulate its nano-size andnanostructure; on the other side, the WO₃hydrogen sensors got in traditional waysmust work in high temperature, which raises the safety loophole. The low SNR （Signalto Noise Ratio） also reduce the stability of sensors. Thus, we present a new methodsynthesizing WO₃hydrogen sensors with the help of highly ordered block copolymertemplate which could have various nanostructures. This new WO₃hydrogen sensorscould work at room temperature, have high sensitivity and high SNR, meanwhile, wediscuss the different factor which influence the hydrogen sensitivity. The specific workis as follows:Firstly, we synthesized WO₃with highly ordered nanostructure of particles androds with the help of PS-b-P4VP block copolymer template. The effects ofnanostructure of template, immersing period, UV exposure period, and the rate ofcalcinations were also investigated. The different nanostructure formation of templateis due to micro phase separation when block copolymer appears self-assemble, whilethe P4VP phase could attract H₂WO₄which could make WO₃the same structure astemplate. It is demonstrated that the WO₃synthesized by block copolymer appearshighly ordered nanostructure, and could be changed with template’s structure.Secondly, WO₃fabricated with template was tested hydrogen sensitivity. Theeffect of substrate, calcinations temperature, and nanostructure were also investigated.Response time, working temperature and sensitivity were used to measure itsperformance when exposure to6%and0.01%concentration H₂. It is demonstrated that the WO₃synthesized through block copolymer template could be more sensitive, stableand higher SNR when compared to traditional WO₃working at room temperature.Thirdly, the mechanism of WO₃hydrogen sensor fabricated by block copolymertemplate was investigated, and the other factor which effects. We present the principlethat the heterojunction between WO₃nanoparticles and the conductive carbon filmwhich was changed from block polymer template after calcination, and it wasdemonstrated by experiment.