The Preparation And Application Of AgFeO₃and Co₃O₄Semiconductor Nanomaterials

In recent decades, nanomaterials have become the research focus dueto the novel optical, electrical, magnetic, acoustic, thermal, mechanicaland other properties. As the important part of inorganic functionalmaterials, metal oxide semiconductor nanomaterials have been widelyapplied in many research fields, such as surface-enhanced Ramanscattering, gas sensors, supercapacitors, lithium-ion batteries and catalysts.Thus, in this paper, AgFeO2nanoparticles and porous Co3O4ultrathinnanosheets were synthesized and used in SERS, gas sensors andsupercapacitors. The main contents are as follows:(1) AgFeO2nanoparticles were prepared via a facile hydrothermalmethod, and then were employed as SERS substrates using Rhodamine6G and4-mercaptobenzoic acid as probe molecules. The detection insolution has ensured the reproducibility of the substrates and theuniformity of the SERS signals. It was noticed that the substrate revealedhigh SERS effect at1×10-7M R6G with an enhancement factor of1×105, showing the high SERS activity for semiconductor. In addition, theAgFeO2nanoparticles substrate has excellent temporal stability by furthertesting.(2) The synthesized AgFeO2nanoparticles via a facile hydrothermalmethod were irradiated with gamma ray of different doses. Theseproducts were characterized with XRD, UV-vis absorption spectrum andTEM. The results showed that the crystal structure, morphology and sizehad no distinct variation, whereas the UV-vis absorption intensitiesobviously enhanced after irradiation. The non-and irradiated AgFeO2nanoparticles were employed to fabricate gas sensors to detect ethanol.The experimental results showed that the non-irradiated AgFeO2nanoparticles sensor has the highest sensitivity (s=30.2) at180C. Itwas interesting that the irradiated AgFeO2nanoparticles sensor has thehighest sensitivity (s=36.8) at140C. The experimental results suggested that gamma ray irradiation can improve the gas sensingproperties of the AgFeO2nanoparticles.(3) The porous Co3O4ultrathin nanosheets were synthesized viasolvothermal and subsequent thermal decomposition methods, ethyleneglycol and water were used as mixture solvent. The electrochemicaltesting results showed that the specific capacitances were150、136、118and95F g-1at current densities of1,2,4and8A g-1, respectively, andthe specific capacitance retention of78.5%after2000cycles at2A g-1.The gas sensing results showed that the Co3O4sensor has the highestsensitivity (s=14.3) to200ppm at160C. We also investigated thesensitivity of the sensor to200ppm different gases, the result showed thatthe sensor is selective to ethanol and acetone.