Preparation Ot Ordered Mesoporous Ferrite And Its Application In Gas Sensors

Environmental problem brought by air pollution have been attracting more and more attention.Hence advanced gas sensors for the detection of toxic and harmful gases are highly desired,where it is important to design gas sensing materials with excellent properties such as high sensitivity,high selectivity,long-term stability.Monometallic oxides such as tin oxide,zinc oxide,hematite,have been extensively investigated for gas sensors,whereas the research on compound metal oxides is relatively rare.In this paper,a series of mesoporous ferrites with high specific surface area and ultrathin framework and the derived composite were synthesized by hard template method,whose mesostructured parameters(such as pore size and specific surface area)and chemical composition were modulated for improving their gas sensing properties.A series of mesoporous nickel-based ferrites were synthesized by using ordered mesoporous silica KIT-6 as hard template,whose pore size were reduced with decreasing their hydrothermal aging temperatures(from 140,130,100,80 to 40?).The resultant mesoporous nickel-based ferrites exhibit relatively high specific surface area(up to 202 m2/g),which gradually increased with decreasing the pore size of KIT-6.It can be found that the ordered mesoporous nickel-based ferrite with largest specific surface area has a higher response(Rgas/Rair=58)to 1 ppm toluene than other gases at the working temperature of 230?.A series of nickel-based ferrite composite with different ratio of Ni2+and Fe3+were also synthesized by using KIT-6 as hard template,whose response to 1 ppm acetone is up to 27.2 when Ni2+/Fe3+?1:2.4Similarly,zinc-based ferrites were also synthesized by using ordered mesoporous silica KIT-6 as hard template,where the highest specific surface area is up to 181 m2/g.Gas sensing testing results show that mesoporous zinc-based ferrite has good selectivity to H2S and the response of mesoporous zinc-based ferrite with the highest specific surface area to 1 ppm H2S is higher than those of other zinc-based ferrite at the working temperature of 200?.Moreover,mesoporous copper-based ferrites were obtained by similar proceduce,which exhibited high specific surface area(up to 134 m2/g).Gas sensing testing results show that mesoporous copper-based ferrite material has good selectivity to H2S at the working temperature of 200?,whose response to 5 ppm H2S could be up to 42.8.