电容式铜掺杂氧化锌湿度传感器的特性

通过水热法制备不同原子数分数铜(Cu)掺杂氧化锌(ZnO)纳米棒材料,并通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)和X射线光电子能谱仪(XPS)对所制备样品的结构形貌及表面价态进行表征与测量。采用介电泳(DEP)操控技术将不同材料按照电场的分布均匀排列在叉指电极之间,制成电容式湿度传感器。测试数据表明与未掺杂ZnO样品相比,Cu掺杂ZnO样品尤其是原子数分数2%及5%Cu掺杂ZnO,具有更好的灵敏度等传感特性。Freundlich模型拟合结果表明,Cu掺杂能够有效提高材料的湿度吸附强度与容量。同时结合复阻抗频谱与多层吸附理论对传感机理进行深入讨论,结果表明适量Cu掺杂能够有效提高敏感材料中氧空位浓度,进而提供更多吸附位点,提高湿度传感特性。     

Influence factors on activity of Ru–Zn catalysts in selective hydrogenation of benzene

Selective hydrogenation of benzene is an atom economic green route to produce cyclohexene. The control of Zn species is the key to the catalytic performance of Ru–Zn catalysts. The influences of ZnO crystals on selective hydrogenation of benzene were explored. A series of Ru–Zn catalysts with different Zn contents and ZnO morphologies were prepared by changing the amount of NaOH in the co-precipitation process. The catalysts were characterized by N_2 physisorption, X-ray powder diffraction(XRD), inductively coupled plasma optical emission spectrometer(ICP-OES), scanning electron microscope(SEM), temperature-programmed reduction(H_2-TPR)and Malvern laser particle size analyzer. It is found that with increasing the amount of NaOH, the Zn content first increased then decreased, and the ZnO crystals changed from relatively thicker pyramidal-shaped crystals to slimmer needle-shaped crystals. The catalyst had the highest Zn content(22.1%) and strongest interaction between ZnO crystals and Ru particles at pH 10.6 of the solution after reduction. As a result, it had the lowest activity. The activity of Ru–Zn catalysts is affected by both the Zn content and the interaction between ZnO crystals and Ru particles. The effect of reduction time was also investigated. Prolonging the reduction time caused no significant growth of ZnO crystals but the aggregation of catalyst particles and growth of Ru nanocrystals, thus resulting in the decrease of catalytic activity.     

Catalytic performance of hybrid Pt@ZnO NRs on carbon fibers for methanol electro-oxidation

A novel Pt@ZnO nanorod/carbon fiber (NR/CF) with hierarchical structure was prepared by atomic layer deposition combined with hydrothermal synthesis and magnetron sputtering (MS). The morphology of Pt changes from nanoparticle to nanorod bundle with controlled thickness of Pt between 10 and 50 nm. Significantly, with the increase of voltage from 0 to 0.6 V (vs. standard calomel electrode), the prompt photocurrent generated on ZnO NR/CF increases from 0.235 to 0.725 mA. Besides, the Pt@ZnO NR/CF exhibited higher electrochemical active surface area (ECSA) value, better methanol oxidation ability and CO tolerance than Pt@CF, which demonstrated the importance of the multifunctional ZnO support. As the thickness of Pt increasing from 10 to 50 nm, the ECSA values were improved proportionally, leading to the improvement of methanol oxidation ability. More importantly, UV radiation increased the density of peak current of Pt@ZnO NR/CF towards methanol oxidation by additional 42.4%, which may be due to the synergy catalysis of UV light and electricity.     

Mn掺杂对Al-ZnO吸附剂H2S常温脱除性能的促进作用

采用共沉淀法制备了一系列ZnO、Al-ZnO和x-Mn-Al-ZnO吸附剂,在常温条件下测试样品的H2S脱除性能。通过N2物理吸附、X射线衍射（XRD）、扫描电子显微镜（SEM）、X射线光电子能谱（XPS）对吸附剂进行表征,考察其形貌结构及表面物理化学性质。脱硫性能测试结果显示,随着Mn含量的增加,脱硫性能呈现先增大后减小,再增大再减小的趋势,两个极值点分别出现在0.02Mn-Al-ZnO和0.08Mn-Al-ZnO。结合表征结果发现,不同Mn掺杂量对Al-ZnO吸附剂的脱硫性能表现出不同的促进作用机制。0.02molMn掺杂主要是提高Al-ZnO吸附剂的比表面积至171.4 m2/g,进而促进其H2S脱除性能;随着Mn掺杂量增加,其比表面积下降,但更多的Mn进入ZnO晶格导致Mn和Zn之间相互作用增强,进而促进脱硫性能;然而随着Mn掺杂量进一步增加,吸附剂比表面积继续下降,并且生成ZnMn2O4晶相,导致脱硫性能的下降。0.08Mn-Al-ZnO脱硫性能最佳,在25 oC,空速3000 h-1,H2S浓度1000 ppmv条件下,穿透硫容为7.21g S/100 g sorbent。本研究表明,不同Mn掺杂量会导致吸附剂的形貌结构、晶相和表面物化性质不同程度的变化,而由不同影响因素主导的x-Mn-Al-ZnO吸附剂表现出脱硫性能的差异。     

Mn掺杂对Al-ZnO吸附剂常温脱除H_2S性能的促进作用

采用共沉淀法制备了ZnO、Al-ZnO和一系列xMn-Al-ZnO(x为Mn的物质的量)吸附剂,在常温条件下测试了样品的脱除H_2S性能。通过N_2物理吸附、XRD、SEM、XPS对吸附剂进行了表征,考察了其形貌结构及表面物理化学性质。脱硫性能测试结果显示,随着Mn含量的增加,吸附剂脱硫性能呈现先增大后减小再增大再减小的趋势,两个极值点分别出现在0.02Mn-Al-ZnO和0.08Mn-Al-ZnO。结合表征结果发现,不同Mn掺杂量对AlZnO吸附剂的脱硫性能表现出不同的促进作用。0.02 mol Mn掺杂能提高Al-ZnO吸附剂的比表面积至171.4m~2/g,进而促进其H_2S脱除性能;随着Mn掺杂量增加,吸附剂比表面积下降,但更多Mn进入ZnO晶格导致Mn和Zn之间相互作用增强,进而促进脱硫性能;然而,随着Mn掺杂量进一步增加,吸附剂比表面积继续下降,并且生成ZnMn_2O_4晶相,导致脱硫性能下降。0.08Mn-Al-ZnO的脱硫性能最佳,在25℃,体积空速3 000 h~(-1),H_2S质量浓度1.39×10~(-3)g/L条件下,穿透硫容为7.21%。结果表明,不同Mn掺杂量会导致吸附剂的形貌结构、晶相和表面物化性质发生不同程度的变化,由不同影响因素主导的x Mn-Al-ZnO吸附剂表现出脱硫性能的差异。     

ZnO不同微结构/Cu_4Bi_4S_9异质结光生电荷分离机制与光电性质

采用不同方法分别制备出ZnO纳米颗粒、纳米线、纳米棒、纳米管等4种微结构薄膜,以Cu_4Bi_4S_9(CBS)纳米带为电子给体制备出ZnO不同微结构/CBS异质结。稳态光电压谱结果表明各异质结构都具有优于单一组分的光伏响应,而且光伏性质呈现出,ZnO纳米管/CBS>ZnO纳米棒/CBS>ZnO纳米线/CBS>ZnO纳米颗粒/CBS的特点。较弱正外电场诱导下各异质结构仍然保持稳态下的光伏响应特性。随着外电场逐步提高,ZnO纳米颗粒/CBS光伏性质增加显著,+2 V电压诱导下,ZnO纳米颗粒/CBS已接近ZnO纳米管/CBS光伏响应强度,并明显高于另外2类异质结构光伏性质。从电子受体微结构、异质结厚度、内建电场、能级匹配等方面,分析了关键因素的综合作用对光生电荷分离和收集效率的影响。     

碳微球对中空ZnO结构和药物缓释性能的影响

以碳微球为模板制备中空ZnO微球,接着采用浸渍法将防霉剂填充在中空ZnO微球中,同时对其在水中的缓释效果进行了研究.采用扫描电镜(SEM)和透射电镜(TEM)研究了反应时间和葡萄糖浓度对碳微球形貌的影响,以及不同碳微球模板对中空ZnO微球形貌和结构的影响.SEM和TEM测试结果表明:采用水热法成功地制备了尺寸为50~200nm的碳微球和40nm左右的中空ZnO微球.缓释实验结果表明:载药中空ZnO微球从1h到9h释放的防霉剂浓度从0.008 3mg/mL增加到0.021 4mg/mL,缓释效果明显.     

高压高温制备Sb掺杂的P型ZnO及电致发光

以ZnO和Sb_2O_3为前驱物,在5GPa、1100~1450℃条件下,制备出电学性能稳定的掺Sb的p型ZnO(记作ZnO:Sb)。其中1450℃掺杂4.6%Sb时合成了性能最好的P型ZnO:Sb,电阻率为1.6×10~(-2)Ωcm,载流子浓度为3.3×10~(20)cm~(-3),迁移率为12.1cm/V s。p型导电是由位于Zn位的Sb和两个Zn空位组成的复合受主引起的。测定了受主能级为113meV,讨论了压力对p型ZnO的形成和电性能的影响。此外,以高质量ZnO纳米线作为LED的发射层,通过将p型ZnO:Sb中的空穴注入ZnO纳米线中实现了激光发射。当注入电流达到20mA时,电致发光(EL)的功率可达到10mW。     

Au修饰ZnO纳米带制备及光催化特性研究

通过水热法制备ZnO纳米带,通过溅射的方法在ZnO纳米带进行表面Au修饰.通过扫描电镜、X射线衍射、光致发光等测试手段对样品的形貌、结构和光学性质进行表征.研究ZnO纳米带Au修饰前后的光催化活性的变化.结果表明,Au修饰ZnO纳米带样品对甲基橙降解效果有明显的提高.     

Surface passivation of nanocrystalline silicon powder derived from cryomilling

The surface passivation mechanism of nanocrystalline silicon powder was studied. The liquid nitrogen/argon was used as the medium to prepare the nanocrystalline silicon powder, using a cryomilling technology. The X-ray diffraction, transmission electron microscopy, plasma emission spectroscopy and infrared spectrum were used to analyze the prepared samples, and density functional theory was used to investigate the cryomilling process. For nanocrystalline silicon powder cryomilled with liquid N2, the amorphous outer layer with N element is formed On the surface, and chemisorption caused by the formation of Si-N-Si bond leads to the surface passivation; although physisorpfion also he confirmed, the Si-N bond is steady after exploded in air for 30 days and no new bond is observed. For nanocrystalline silicon powder cryomilled with liquid At, no new chemical bond is Observed, Ar element absorbs on the surface of the prepared powder only through physisorption, and after exploded in air for 30 days, a Si-O bond can be observed obviously.