Ultra-thin ALD CoO_(x)-ZnO heterogenous films as highly sensitive and environmentally friendly H_(2)S sensor

To obtain environmentally friendly,integrated and miniaturized gas sensors for the increasing request for the Internet of Things industry and other relative areas,the ultra-thin CoO_(x)/Zn O heterogeneous film with active interfacial sites was in-situ deposited on micro-electro-mechanical systems(MEMS)as H_(2)S sensor.Atomic layer deposition(ALD)was employed to in-situ fabricate the uniform Zn O thin film.ALD CoO_(x)was deposited on ZnO surface to obtain CoO_(x)/Zn O heterojunction and active interfacial sites.The ultra-thin film(20 nm)with 50 ALD Co O_(x)decorated on 250 ALD Zn O displays excellent sensing performance,including very high response(4.45@200×10^(-9))and selectivity to H_(2)S with a limit of detection(LOD)of 0.38×10^(-9),long-term sensing stability,high response/recovery performance(7.5 s/15.7 s)and mechanical strength at 230。C.Reasons for the high sensing performance of CoO_(x)/Zn O have been confirmed by series of characterizations and density functional theory(DFT)calculation.Heterojunction film thickness with Debye length,the oxygen vacancies and the synergistic effect of active interfacial sites are main reasons for the high sensing performance.The strategy by fabrication of CoO_(x)/Zn O heterogeneous film within Debye length and employing synergistic effect of active interfacial sites offers a promising route for the design of environmentally friendly gas sensors.Furthermore,the ALD technique offers a facile in-situ strategy and high-throughput fabrication of MEMS gas sensors.

Study on photocatalytic activity of MoS2/ZnO composite in visible light

A series of MoS_2/ZnO compound photocatalysts with different mass ratios were successfully prepared by hydrothermal method. The X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), scanning electron microscope(SEM) and UV-vis absorption were used to characterize the prepared MoS_2/ZnO photocatalysts. It was proved that the combination of Mo S2 and Zn O can increase the content of oxygen vacancies on surface of Zn O, thus improving the light absorption capacity in visible light region and reducing the band gap of Zn O. And the photocatalytic performance of Zn O was improved. Experimental results show that the MoS_2/ZnO(3 wt%) compound has the highest degradation rate for methylene blue(MB) under visible light, which means that it has the best photocatalytic activity among all the prepared samples.

Synthesis,characterization and antioxidant activities of highly functionahzed cyclopentadienes catalyzed by ZnO-nanorod as economic and efficient heterogeneous nano catalyst

A three-component condensation was applied for the preparation of cyclopentadiene derivatives through the reaction of primary amines,alkyl propiolate and dialkyl acetylenedicarboxylate in the presence of catalytic amount of ZnO-nanorods（Zn-NR） under solvent-free conditions at 50 ℃.The method has proved to be synthetically green,simple,and effective with high atom economy and yield.The catalyst also revealed significant reusability.Moreover,the antioxidant activity and free radical scavenging capacity of the newly synthesized derivatives 4a,4b,4c,and 4d was screened using free radical scavenging 2,2-diphenyl-1-picrylhydrazyl（DPPH） and ferric reducing antioxidant power（FRAP）assays and compared with hydroxytoluene（BHT） and tert-butylhydroquinone（TBHQ）.These compounds do not exhibit good DPPH radical scavenging,but they have a desirable FRAP.

Tuning the Microstructural and Magnetic Properties of ZnO Nanopowders through the Simultaneous Doping of Mn and Ni for Biomedical Applications

Undoped and Mn＋Ni doped ZnO nanopowders were synthesized using a simple soft chemical route by varying the Ni doping level （1, 3, 5 and 7 at.%） and keeping the Mn doping level （10 at.%） constant, X-ray diffraction studies reveal that the incorporated Ni^2＋ ions form a secondary phase of cubic NiO beyond the Ni doping level of 3 at.%, which is also confirmed by Fourier transform infrared spectroscopy. The band gap of the nanopowders increases （from 3.32 to 3.44 eV） up to 3 at.% of Ni doping and decreases with further doping. ZnO：Mn：Ni nanopowders with 3 at.% of Ni concentration exhibit good antibacterial efficiency. The variation in the size of the nanoparticles, as observed from the TEM images and hydroxyl radicals as evidenced from the photoluminescence results, clearly substantiate the discussion on the antibacterial efficiency of the synthesized nanopowders. Magnetic properties of the synthesized nanopowders were studied using a vibrating sample magnetometer, and the results showed that the doping of Mn and Ni largely influences the magnetic properties of ZnO nanopowders.