Preparations And Performance Of Co₃O₄ And ZnO With Special Morphology

Morphology of nanomaterials has an important influence on its performance.The nanomaterials with special morphology and unique structure own more excellent properties compared to common block materials,and have become hot spots of research in the field of material science.C0₃O₄ and ZnO,as two important functional materials of metal oxide semiconductors,have considerable applications in many fields,such as gas sensors,photocatalysis and electrode materials etc.In this paper,Co₃O₄ and ZnO with special morphologies successfully grew on substrates in the absence of template agents,surfactants and seed crystals by hydrothermal or chemical bath methods,and their photocatalysis and gas sensing performances had been investigated in detail.The main contents and results were as follows:?1?The fiber arrays of Co₃O₄?marked as Co₃O₄-FAs?,which has sharp tops and approximately 100nm in diameter was successfully prepared on the substrates of conductive glasses?marked as ITO?and gas sensing ceramic tubes?marked as CT?by hydrothermal process using cobalt nitrate as the source of cobalt.Due to its high ratio of length to diameter and good orientation,the related performance of Co₃O₄-FAs has been enhanced,it possesses remarkable properties in Faradic pseudocapacitance and photocatalysis.In addition,Co₃O₄-FAS directly growing on CT have higher sensitivity and selectivity towards ethanol gas,its sensitivity was 1.5 and 4 times respectively to the gas sensors which used powders of Co₃O₄-FAs and Co₃O₄ particles as sensitive materials by traditional coating process.?2?The urchin-like Co₃O₄?marked as Co₃O₄-UCs?with 10-12?m in size and assembled by 4-5 ?m nanofibers grew on ITO and CT through hydrothermal method.The highly radial and open structure endows Co₃O₄-UCs with larger specific surface area?79.99m2/g?and is beneficial to the efficient injection and transmission of electrons,thus promotes photocatalytic efficiency and gas sensitivity increasing to 1.3 and 5.7 times compared with the powder of Co₃O₄ respectively.?3?The porous rhombus-shaped ZnO nanorod arrays?marked as ZnO-RRs?assembled with nanoplates was prepared on ITO and CT using hydrothermal method.Because of the particular structure and F-doping,the ZnO-RRs possesses higher photocatalysed activity than powder samples under ultraviolet light.In addition,the ZnO-RRs shows high sensitivity and selectivity and quick response towards acetone gas,the sensitivity to 1000ppm acetone gas reaches up to 113.15.?4?The hexagonal flower-like ZnO?marked as ZnO-FLs?was synthesized by chemical bath method and further studied through loading nano-gold?marked as ZnO-AFLs?.The results show that the absorption peak of ZnO-FLs extends to whole visible region,and the efficiency of ultraviolet photocatalysis increases 4 times after loading nano-gold.Gas sensing tests indicate that the sensitivity of ZnO-AFLs reach to 153 towards 1000ppm acetone gas,which was 2.25 times as high as ZnO-FLs,and the corresponding response time is only 0.83s.