earticle

영어

Recently, hydrogen as a renewable energy carrier has attracted attentions for fuel cell vehicles, energy storage and generation, bio and health applications. However, there is a critical issue of hydrogen about safety because hydrogen is colorless, odorless and explosive in 4 % H2 in air. This characteristic has been considered as a bottle-neck to spread hydrogen-based applications.1 In addition, it is essential to monitor hydrogen concentration at high precision over wide range of concentration at ppm- 100%. Hence, the research on hydrogen detecting sensor to ensure hydrogen safety and wide-range concentration control has been actively conducted. In addition to the typical electrical sensing, recent research on hydrogen gas sensors has focused on optical sensor using IR detector but it is subject to critical issues of a high cost, lots of electrical connections2 and accidental errors. Now, visible coloration hydrogen sensor (chemochromic) has been reported with various materials3. This chemochromic sensor is electrical power-free and is available in flexible applications. In this presentation, I report various hydrogen sensing technique based on our group developed active materials such as (1) nanostructure oxides (WO3, MoO3) for reversible and sulfide (CuS) for irreversible for chemochromic sensing, (2) super lattice structure based on Pd alloy for wide range hydrogen dissociation from 100 ppm to 100 %. Chemochromic hydrogen sensor with catalyst can dissociate molecular hydrogen and then, atomic hydrogen diffuse into lattice of nano-columnar WO3 and MoO3. In the diffusion process, the interaction between hydrogen and oxides generates unpaired d-spin providing polaron effect that is formed with ion core and unpaired d electrons. Then, visible coloration that consists of plasmonic effect and a H-defect state appears from transparent to blue. The measurement of coloration is conducted with color difference (ΔE^*). In case of the Pd-WO3, hydrogen detection from 0.1 to 100 % is confirmed with fast response ΔE^*>20 and remarkable selectivity against CH4 and CO. Moreover, the sensor shows a possibility to use multi-modal sensor that involves resistance and chemochromic method. Besides, we discuss a subject to expand hydrogen applications with a precise hydrogen concentration determination by using high precise H2 concentration sensor and with hydrogen associated health applications such as hydrogen containing water.