青霉素在硼掺杂金刚石薄膜电极上的电化学行为研究

采用直流等离子体化学气相沉积法制备了硼掺杂金刚石(BDD)薄膜电极。利用循环伏安法(CV)和电化学交流阻抗谱(EIS)研究青霉素在BDD电极上的电化学过程,并利用等效电路对相关的电极动力学参数进行了拟合。研究表明,青霉素G钠在电极上的电化学氧化过程为不可逆过程,氧化峰电位为2.2 V,没有还原峰出现,电极表面有中间产物的吸附,但在高于水分解电压下氧化能够恢复原来的活性。当电极电位在开路电位(OCP)至1.5 V时,电极过程由电荷传递过程和传质扩散过程共同控制,即电化学极化与浓差极化同时存在;当电极电位在1.8～2.5 V时,电极过程由电荷传递过程控制。     

青霉素在硼掺杂金刚石薄膜电极上的电化学行为研究

采用直流等离子体化学气相沉积法制备了硼掺杂金刚石(BDD)薄膜电极。利用循环伏安法(CV)和电化学交流阻抗谱(EIS)研究青霉素在BDD电极上的电化学过程,并利用等效电路对相关的电极动力学参数进行了拟合。研究表明,青霉素G钠在电极上的电化学氧化过程为不可逆过程,氧化峰电位为2.2 V,没有还原峰出现,电极表面有中间产物的吸附,但在高于水分解电压下氧化能够恢复原来的活性。当电极电位在开路电位(OCP)至1.5 V时,电极过程由电荷传递过程和传质扩散过程共同控制,即电化学极化与浓差极化同时存在;当电极电位在1.8～2.5 V时,电极过程由电荷传递过程控制。     

Pt-Ir共沉积电位对电解氨水制氢的性能影响

为研究在线电解氨水为氢燃料电池供氢的可行性,采用电化学共沉积法,在不同沉积条件下制备了Pt-Ir催化电极,用循环伏安法（CV）与计时安培法（I-t）结合电镜、XPS和XRD结构分析,研究了电极对氨水的电解催化性能。结果表明,沉积电位影响了合金催化剂的组成、晶型、晶粒尺寸等,从而进一步影响了电极在氨催化过程中的性能。当沉积电位固定,电极上的催化剂负载量、氨水电解过程中催化剂的形貌、结构、组成基本稳定。其中,-0.05 V（vs. SCE）沉积电位下制备的催化剂在氨的电解催化过程中持续性和稳定性好,催化剂的负载量和过电位也最低。利用电化学上电解氨和生成水电位上的差异,将氨电解为燃料电池供氢,在低电流密度下(<10 mA/cm²)燃料电池为氨电解池提供能量的同时仍然有40%以上的额外功率用于其他负载。     

RF-PCVD法制备纳米碳化钨微晶的研究

采用高频等离子体化学气相沉积法(RF-PCVD),以WCl6 C2H2 H2的反应体系来制备纳米碳化钨微晶,实验制得了粒径小于100nm,平均粒径为50nm的纳米碳化钨微晶样品。理论分析和实验结果都表明:RF-PCVD法制备的碳化钨样品比较复杂,含有WC,W2C,WC1-x等三种碳化钨。其中WC的硬度较高,而W2C,WC1-x的催化活性较好。     

顺丁烯二酸在锡电极上的动力学参数研究

采用稳态极化法和不同温度下稳态极化曲线法研究了酸性介质中顺丁烯二酸在锡电极上阴极还原的动力学过程,计算了相关的动力学参数,结果表明：顺丁烯二酸在锡电极上的交换电流密度i0为0．0024A／cm2,传递系数仅为0．288,表观活化能为19．266kJ／mol,低于顺丁烯二酸在铅电极上电还原反应的表观活化能,证明顺丁烯二酸在锡电极上更容易被还原。     

多孔锡电极的制备及其用于CO_2电化学还原性能

用氢气泡动态模板法在铜基底上沉积锡制备了一种新型锡电极。采用SEM、EDS和XRD对多孔锡沉积层进行表征,并对其催化CO_2电化学还原制甲酸的性能进行了研究。SEM结果表明多孔锡沉积层具有自组织的蜂窝状三维多孔结构,同时EDS分析表明电极表面无杂质。XRD表征表明在基底和Sn沉积层交界处有Cu_5Sn_6合金生成,加强了两者之间的连接。采用不同扫描速率下循环伏安曲线法测试电化学表面积,多孔锡电极的电化学表面积大约是普通锡片电极的6倍。电极的循环伏安测试结果表明,多孔锡电极比普通锡片电极具有更高的电流密度,更正的起峰电位,说明具有多孔结构的电极对CO_2电化学还原反应具有更高的活性。通过考察KHCO_3浓度、还原电位对还原过程的影响,确定KHCO_3浓度为0.5 mol/L,还原电位为-1.7 V vs.SCE时,甲酸的电流效率可达73.9%。由此可见,多孔结构电极材料能有效地提高CO_2电还原的催化效果。     

类金刚石薄膜在模拟体液中的电化学阻抗

利用双放电腔微波等离子体源全方位离子注入设备,分别采用等离子体增强化学气相沉积技术、等离子体源离子注入和等离子体增强化学气相沉积复合技术两种工艺对医用3161,不锈钢进行类会刚石薄膜表面改性。利用电化学阻抗谱法考察了两种工艺制备的类金刚石薄膜在模拟体液中的抗腐蚀性能。结果表明：与采用等离子体增强化学气相沉积技术制备的类金刚石薄膜相比,在72h的浸泡时间内,采用等离子体源离子注入和等离子体增强化学气相沉积复合技术制备的类金刚石薄膜防腐蚀性能明显增高,腐蚀阻抗较高,碳注入层可有效抑制溶液渗入薄膜和基体之间的界面,起到了腐蚀防护层的作用。动电位极化测试表明：采用复合技术制备的类金刚石薄膜在模拟体液中的腐蚀倾向性更低,钝态稳定性更好。     

电沉积MnO_2薄膜及其性能研究

以纸质电池的正极为研究目标,采用恒电位电沉积的方法,于柔性纸质膜上电沉积了γ-MnO2纳米薄层.经测试,电极表面形貌呈现五敛子状.研究了沉积电位对其电化学性能的影响,发现在0.8 V,vs SCE电位下,恒电位电沉积制得的γ-MnO2电极电化学性能最优.     

N,N-二甲基甲酰胺体系电沉积铋−碲热电薄膜

在N,N-二甲基甲酰胺(DMF)有机溶剂中先通过阴极极化曲线和循环伏安曲线测试研究了Bi(III)、Te(IV)离子及二者混合时在金电极上电沉积的电化学行为.再在不同电位下电沉积制备了Bi-Te热电薄膜,研究了沉积电位对Bi-Te薄膜性能的影响.结果表明,Bi(III)、Te(IV)及Bi-Te在金电极上的电沉积均属于...     

WC/MMT纳米复合材料制备及其对PNP的电催化活性

以剥离后的蒙脱石(MMT)为载体,将浸渍法与原位还原技术相结合制备了碳化钨/蒙脱石(WC/MMT)纳米复合材料。采用X射线衍射、扫描电子显微镜和透射电子显微镜等手段对样品进行了表征。结果表明,剥离后蒙脱石的片层厚度为10～15 nm,层间距增大,边缘发生卷曲;复合材料由碳化钨(WC)、碳化二钨(W₂C)和蒙脱石组成,碳化钨颗粒均匀地分布于蒙脱石外表面。采用循环伏安法测试了样品对对硝基苯酚(PNP)的电化学还原性能,结果表明,WC/MMT纳米复合材料对对硝基苯酚具有良好的电催化活性,且具有较好的稳定性。蒙脱石是碳化钨基复合电催化材料良好的载体。     

WC/C制备条件对甲醇电氧化特性的影响研究

以钨酸铵为前躯体,采用程序升温控制还原法（TPR）制备了WC／C纳米颗粒,在碳载体存在的情况下,研究了钨源前躯体碳化过程中CH4与H2流量比对单-WC晶相以及Pt／WC／C电催化氧化甲醇性能的影响。XRD测试结果发现：仅在CH4：H2流量比为2时可获得单一WC多晶,其平均粒径为11．3nm。循环伏安实验结果证实：10wt％Pt-10wt％WC／C电催化氧化cH,OH的比质量活性达到875mA·mg^-1,远远高于10wt％Pt／C的658mA·mg^-1,且起始氧化电位负移80mV。计时电流法实验表明Pt／WC／C在酸性介值中稳定性高于Pt／C催化剂。     

活性炭载碳化钨复合材料的制备及其对对硝基苯酚的电催化性能

以浓度为10%的偏钨酸铵溶液为前驱体、CH4/H2为还原碳化气氛,采用表面修饰技术和还原碳化技术制备了碳化钨(WC)/活性炭(C)复合材料。通过FT-IR、XRD、SEM等对制备的WC/C材料进行表征,结果表明,酸处理后的活性炭外表面大幅度增加了羟基和羰基,WC/C复合材料是由WC、W2C和C三相组成,碳化钨均匀地分散于活性炭表面,粒径约50～100nm。采用循环伏安法研究了碱性介质中WC/C-PME对对硝基苯酚的电还原行为,结果表明,该材料对对硝基苯酚的电催化活性优于WC和C,且WC/C材料在对硝基苯酚电还原过程中保持良好的化学稳定性。     

碳化钨纳米晶薄膜电极的制备及其对甲醇电氧化性能

引　言碳化钨具有与金属铂相类似的表面电子结构[1], 因此, 人们一直在探索碳化钨在化学领域中的催化性能, 期望利用矿藏丰富、价格低廉的钨矿优势, 用碳化钨来替代资源稀缺、价格昂贵的铂及铂基合金催化剂. 研究表明, 碳化钨在烷烃重整、异构化反应以及在氢析出反应等方面具有     

Nucleation and growth of diamond films on aluminum nitride by hot filament chemical vapor deposition

Nucleation and growth of diamond films on aluminum nitride (ALN) coatings were investigated by scanning electron microscopy, Raman spectroscopy and scratch test. ALN films were grown in a magnetron sputtering deposition. The substrates were Si(111) and tungsten carbide (WC). Chemical vapor deposition (CVD) diamond films were deposited on ALN films by hot filament CVD. The nucleation density of diamond on ALN films was found to be approximately 10⁵ cm⁻², whereas over 10¹⁰ cm⁻² after negative bias pre-treatment for 35 min was −320 V, and 250 mA. The experimental studies have shown that the stresses were greatly minimized between diamond overlay and ALN films as compared with WC substrate. The results obtained have also confirmed that the ALN, as buffer layers, can notably enhance the adhesion force of diamond films on the WC.     

Specialized Study on Morphological Features of Tungsten Carbide Thin Film Synthesis by HFCVD

Tungsten carbide (WC) thin film was fabricated by the hot filament chemical vapor deposition method for 10 min as time deposition at the substrate temperature of 400 and 600 °C, under vacuum in the atmospheres of 95 % argon and 5 % methane gas mixture. In this work, the substrate temperature dependence of the WC properties was discussed. X-ray diffraction was used to identify the growth of structural properties of WC thin film on the Si (100) substrate. In order to investigate the morphological features of samples; raman scattering, field emission scanning electron microscopy and cross-sectional scanning electron microscopy (cross-sectional SEM) were used. Atomic force microscopy, mountains map premium (64-bit version) and Gwyddion software analysis were also used for further investigation. In this study, the analysis of the Minkowski functionals, the motifs, the depth histograms, the statistical parameters, the texture direction and the peak count histograms of the nanostructure surface of samples were implemented. According to the analyses, the WC films had a good crystal quality without any deformity and a low residual stress. The results of this study can accurately be used for a better comprehension of the WC thin film structures and characteristics.     

纳米碳化钨的合成及其电催化活性研究

以钨酸和丙烯腈为原料,采用共沉淀法合成碳化钨（WC）前驱体,于H₂和Ar混合气氛中高温还原碳化制备纳米WC。采用傅立叶红外光谱、X射线衍射及扫描电镜等对试样进行表征,在酸性介质中采用循环伏安法测试Pt/WC电化学催化活性。结果表明,实验合成了较纯的纳米碳化钨,其颗粒形貌近似球形,粒径80 nm左右。Pt/WC的电化学表面积（ESA）较传统的Pt/C有较大提高,10%Pt/WC电流密度为51.2 mA·cm^-2。     

Nucleation and Growth of Diamond Films on Ni-Cemented Tungsten Carbide: Effects of Substrate Pretreatments

The nucleation and growth of diamond films on Nicemented carbide is investigated. Substrates made of WC with 6 wt% of Ni were submitted to grinding, and then to different pretreatments (scratching, etching, and/or decarburization) before diamond deposition. Diamond synthesis was carried out by hot-filament chemical vapor deposition (HFCVD) using a mixture of CH₄ (1% v/v) and H₂. Depositions were performed for different lengths of time with the substrates at various temperatures. The specimens were analyzed before and after deposition by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffractometry (XRD). Raman spectra showed that the phase purity of the diamond films was not affected by the presence of nickel on the substrate surface. After wet etching pretreatments, the nucleation of diamond was enhanced, mainly at the WC grain boundaries. Continuous films were obtained on scratched and etched substrates. The decarburizing treatment led to the formation of metallic tungsten and of brittle nicke–tungsten carbide phases. These phases reacted in the early stages of diamond film formation with gaseous carbon species with a parallel process which competes with stable diamond nucleus formation. The diamond film formed after long-term deposition on these samples was not continuous.     

The effect of tungsten buffer layer on the stability of diamond with tungsten carbide–cobalt nanocomposite powder during spark plasma sintering

WC–Co nanocomposite powder produced by spray pyrolysis–continuous reduction and carbonization technology, diamond coated with tungsten (W) by vacuum vapor deposition and uncoated diamond were used in this study. This work adopted the spark plasma sintering (SPS) process to prepare diamond-enhanced ultrafine WC–Co cemented carbide composite material. The effects of W buffer on the stability of diamond with WC–Co nanocomposite powder during SPS were investigated. Results showed that the uncoated diamond was mechanically embedded in WC–Co cemented carbide matrix, while the diamond coated with tungsten was combined chemically with WC–Co cemented carbide matrix. Moreover, there was a transitional layer between the diamond and the matrix which could improve the thermal stability of the diamond, prevent carbon atom of the diamond from dissolving in Co phase and increase the bonding strength of the interface between the diamond and the matrix.     

甲醇在碳载纳米Pt电极上的电化学研究

应用循环伏安法制备了nano-Pt/GC修饰电极,优化了铂微粒在电极表面的沉积条件,并用扫描电子显微镜(SEM)和在硫酸中的循环伏安曲线对其进行了表征。结果表明铂微粒较为均匀地分散在玻碳电极表面,粒径约为140nm,电极具有很大的比表面积。循环伏安实验结果表明nano-Pt/GC电极对甲醇电氧化的催化活性明显高于铂片电极,在该修饰电极上甲醇正向扫描和反向扫描时的氧化峰电位分别是0.67V和0.49V,峰电流为61.00mA/cm2和50.50mA/cm2,分别是铂片电极上的3.13倍和3.10倍,有效地提高了金属铂的利用率,铂微粒在电极表面的最佳沉积条件是循环次数为100次和沉积速度为5mV/s。