ZnO-based catalysts have been widely used in hydrogenation reactions,but less attention has been paid to the electrocatalytic hydrogenation process on ZnO electrodes.In this work,the preparation of hydrogen species an...ZnO-based catalysts have been widely used in hydrogenation reactions,but less attention has been paid to the electrocatalytic hydrogenation process on ZnO electrodes.In this work,the preparation of hydrogen species and the associ-ated reduction properties under electrochemi-cal processes in aqueous solutions have been in-vestigated on ZnO and Au/ZnO electrodes.The measurements of cyclic voltammetry(CV),X-ray diffraction,and electron paramagnetic resonance(EPR)confirm the formation of hydro-gen species on the interstitial sites(Hi)or on the oxygen vacancy sites(H_(O)).The hydrogena-tion reaction of p-nitrophenol(pNP)at 40μmol/L occurs on both ZnO and Au/ZnO elec-trodes,and the hydrogenation reduction performance of Au/ZnO electrode is better than that of ZnO electrode.CVs show H_(O)species is much more reactive with pNP than Hi species.Compared with the ZnO electrode,the presence of Au on ZnO promotes the formation of H_(O)species and improves the electro-reduction performance to pNP.These results help us to un-derstand the reaction processes related to the electrochemical hydrogenation on ZnO and Au/ZnO surfaces and shed new light on the design of new catalytic hydrogenation systems.展开更多
采用均匀沉淀法合成Zn O纳米颗粒(Zn O NPs),以Zn O NPs为种子,制备水溶性Au/Zn O异质结构。将Au/Zn O异质结构附着于离子液体功能化石墨烯(GN)复合膜上,形成一种新颖的负载型石墨烯复合材料(Au/Zn O/GN)。所构建的青霉素酶-氧化苏木精...采用均匀沉淀法合成Zn O纳米颗粒(Zn O NPs),以Zn O NPs为种子,制备水溶性Au/Zn O异质结构。将Au/Zn O异质结构附着于离子液体功能化石墨烯(GN)复合膜上,形成一种新颖的负载型石墨烯复合材料(Au/Zn O/GN)。所构建的青霉素酶-氧化苏木精修饰Au/Zn O/GN(PH-AZG)传感器在PBS水溶液(p H=7.0)中对青霉素钠检测线性范围为2.5×10^(-14)~3.3×10^(-6)mol/L,检出限达到1.5×10^(-14)mol/L(S/N≥3)。在相同条件下制备5根PH-AZG电极,其响应电流的相对标准偏差(RSD)小于3.2%。同时,在实际牛奶制品中,本方法的检测线性范围为5×10^(-14)~5×10^(-7)mol/L,加标回收率为99.7%~101.4%,RSD为2.3%~3.5%(n=5)。结果表明,本方法对实际牛奶制品中低浓度青霉素钠的检测具有可行性。展开更多
Au/Zn O/n-type Si device is obtained using atomic layer deposition（ALD） for Zn O layer, and some main electrical parameters are investigated, such as surface/interface state（Nss）, barrier height（Φb）, series res...Au/Zn O/n-type Si device is obtained using atomic layer deposition（ALD） for Zn O layer, and some main electrical parameters are investigated, such as surface/interface state（Nss）, barrier height（Φb）, series resistance（Rs）, donor concentration（Nd）, and dielectric characterization depending on frequency or voltage. These parameters are acquired by use of impedance spectroscopy measurements at frequencies ranging from 10 k Hz to 1 MHz and the direct current（DC） bias voltages in a range from-2 V to ＋2 V at room temperature are used. The main electrical parameters and dielectric parameters,such as dielectric constant（ε＂）, dielectric loss（ε＂）, loss tangent（tan δ）, the real and imaginary parts of electric modulus（M and M）, and alternating current（AC） electrical conductivity（σ） are affected by changing voltage and frequency. The characterizations show that some main electrical parameters usually decrease with increasing frequency because charge carriers at surface states have not enough time to fallow an external AC signal at high frequencies, and all dielectric parameters strongly depend on the voltage and frequency especially in the depletion and accumulation regions. Consequently, it can be concluded that interfacial polarization and interface charges can easily follow AC signal at low frequencies.展开更多
The controlled synthesis of ZnO hollow spheres is successfully achieved through a facile solvothermal method using a Keggin-type silicotungstic acid（H_4 Si（W_3 O_（10））_4：HSW） as structure directing agent. The f...The controlled synthesis of ZnO hollow spheres is successfully achieved through a facile solvothermal method using a Keggin-type silicotungstic acid（H_4 Si（W_3 O_（10））_4：HSW） as structure directing agent. The formation process of these hollow spheres is proposed based on a variety of controlled experiments. In addition, Au nanoparticles are loaded onto the surface of ZnO hollow spheres. It is found that the Au-loaded ZnO（Au/ZnO） composites exhibit greatly enhanced activity on oxidizing Rhodamine B（Rh B） under simulated UV or visible light irradiation, compared to the pristine ZnO hollow spheres. The improved performance of Au/ZnO heterostructures is mainly attributed to the enhanced optical absorption and the accelerated separation and migration of photogenerated charge carriers. Moreover, the photocatalytic reaction mechanisms are proposed based on the results of electron spin resonance（ESR） analysis, photoelectrochemical measurements, and photocatalytic evaluation. The results and findings are expected to provide significance to the synthesis of noble metal-semiconductor hybrids towards water purification.展开更多
基金supported by the National Key Re-search and Development Program of China(No.2021YFA1500403)the National Natural Science Foundation of China(No.21773047 and No.U1832180)partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘ZnO-based catalysts have been widely used in hydrogenation reactions,but less attention has been paid to the electrocatalytic hydrogenation process on ZnO electrodes.In this work,the preparation of hydrogen species and the associ-ated reduction properties under electrochemi-cal processes in aqueous solutions have been in-vestigated on ZnO and Au/ZnO electrodes.The measurements of cyclic voltammetry(CV),X-ray diffraction,and electron paramagnetic resonance(EPR)confirm the formation of hydro-gen species on the interstitial sites(Hi)or on the oxygen vacancy sites(H_(O)).The hydrogena-tion reaction of p-nitrophenol(pNP)at 40μmol/L occurs on both ZnO and Au/ZnO elec-trodes,and the hydrogenation reduction performance of Au/ZnO electrode is better than that of ZnO electrode.CVs show H_(O)species is much more reactive with pNP than Hi species.Compared with the ZnO electrode,the presence of Au on ZnO promotes the formation of H_(O)species and improves the electro-reduction performance to pNP.These results help us to un-derstand the reaction processes related to the electrochemical hydrogenation on ZnO and Au/ZnO surfaces and shed new light on the design of new catalytic hydrogenation systems.
文摘采用水热法结合后期热处理技术制备了Au/ZnO多孔纳米片,并对其气敏性能进行了详细研究。Au/ZnO样品是由厚度约一二十纳米的多孔纳米片组成;气敏性能测试发现,在紫外光照射下Au/ZnO多孔纳米片结构对NO 2气体具有室温响应,检测限为100ppb。Au/ZnO传感器对100ppb NO 2气体的响应时间是21.5s,恢复时间是7s,灵敏度是1.25。当NO 2气体浓度增加到50ppm时,Au/ZnO传感器的灵敏度增加到138.3,是纯ZnO传感器的2.9倍。分析认为,Au/ZnO优异的室温气敏性能是由于在紫外光照射下材料内部产生光生电子-空穴对以及Au颗粒的催化作用。本论文为高性能、低功耗室温气体传感器的构筑提供了一种简易的方法。
文摘Au/Zn O/n-type Si device is obtained using atomic layer deposition（ALD） for Zn O layer, and some main electrical parameters are investigated, such as surface/interface state（Nss）, barrier height（Φb）, series resistance（Rs）, donor concentration（Nd）, and dielectric characterization depending on frequency or voltage. These parameters are acquired by use of impedance spectroscopy measurements at frequencies ranging from 10 k Hz to 1 MHz and the direct current（DC） bias voltages in a range from-2 V to ＋2 V at room temperature are used. The main electrical parameters and dielectric parameters,such as dielectric constant（ε＂）, dielectric loss（ε＂）, loss tangent（tan δ）, the real and imaginary parts of electric modulus（M and M）, and alternating current（AC） electrical conductivity（σ） are affected by changing voltage and frequency. The characterizations show that some main electrical parameters usually decrease with increasing frequency because charge carriers at surface states have not enough time to fallow an external AC signal at high frequencies, and all dielectric parameters strongly depend on the voltage and frequency especially in the depletion and accumulation regions. Consequently, it can be concluded that interfacial polarization and interface charges can easily follow AC signal at low frequencies.
文摘The controlled synthesis of ZnO hollow spheres is successfully achieved through a facile solvothermal method using a Keggin-type silicotungstic acid（H_4 Si（W_3 O_（10））_4：HSW） as structure directing agent. The formation process of these hollow spheres is proposed based on a variety of controlled experiments. In addition, Au nanoparticles are loaded onto the surface of ZnO hollow spheres. It is found that the Au-loaded ZnO（Au/ZnO） composites exhibit greatly enhanced activity on oxidizing Rhodamine B（Rh B） under simulated UV or visible light irradiation, compared to the pristine ZnO hollow spheres. The improved performance of Au/ZnO heterostructures is mainly attributed to the enhanced optical absorption and the accelerated separation and migration of photogenerated charge carriers. Moreover, the photocatalytic reaction mechanisms are proposed based on the results of electron spin resonance（ESR） analysis, photoelectrochemical measurements, and photocatalytic evaluation. The results and findings are expected to provide significance to the synthesis of noble metal-semiconductor hybrids towards water purification.
