胶态Pt/C催化剂对甲醇的电催化氧化性能

研究了Pt金属载量为20%的碳载胶态Pt金属催化剂对甲醇的电催化氧化性能,并与E TEK公司同类型催化剂进行了比较。X衍射光谱(XRD)和透射电镜(TEM)研究显示在胶态Pt/C催化剂中,Pt粒子的平均粒径为3.8nm,并且具有良好的均一度。电化学研究显示:尽管胶态Pt/C催化剂拥有相对较小的电化学活性面积,但对甲醇的电催化氧化性能却明显优于E TEK公司的Pt/C催化剂,其原因应归结于利用有机溶胶法制得的胶态Pt/C催化剂拥有更合理的平均粒径。

碳杂Ni（OH）2微球的制备及对葡萄糖电催化氧化性能研究

近年来，Ni（OH）2的制备和应用受到关注，尤其是纳米Ni（OH）2以其高的质子扩散系数及优良的电化学性能而备受关注。利用纳米材料研制无酶型葡萄糖电化学传感器也引起了人们的兴趣，如Zhang等通过电沉积的方法，将MnO2固定在纳米碳管上，制得了MnO2基无酶型葡萄糖电化学传感器。

Pt电极上吸附原子对正丙醇电催化氧化性能的影响

用电化学循环伏安和石英晶体微天平研究了碱性介质中正丙醇在 Pt电极和以 Sb,S吸附原子修饰的 Pt( Pt/Sbad和 Pt/Sad)电极上电催化氧化过程 .结果表明正丙醇的氧化与溶液酸碱性关系密切 .酸性介质中正丙醇在 Pt电极上的 CV曲线有两个正向氧化峰 ,而碱性介质中只有一个正向氧化峰 ,第二个氧化峰的消失可能是由于碱性介质中电极钝化引起的 .与 Pt电极相比较 ,饱和 Sb吸附原子修饰的 Pt电极使碱性介质中正丙醇氧化的峰电位负移了 0 .1 0 V,峰电流增加了 2 .2倍 ,表现出显著的电催化活性 .相反 ,Pt电极表面 S吸附原子抑制了正丙醇的电氧化 .还从表面质量变化提供了吸附原子电催化作用的新数据 .

铂电极上锑吸附原子对1,2-丙二醇电催化氧化性能的影响

运用电化学循环伏安(CV)和电化学原位石英晶体微天平(EQCM)研究了Pt电极表面不可逆吸附Sb原子的电化学特性以及Pt电极上Sb吸附原子对0.1mol·L-1H2SO4溶液中1,2 丙二醇电催化氧化性能的影响.研究发现,当扫描电位的上限Eu≤0.50V(SCE)时,Sb可以稳定地吸附在Pt电极表面,饱和覆盖度为0.34;通过控制电位扫描上限和扫描圈数剥离部份Sb可方便地得到Sbad的不同覆盖度;Pt电极表面Sb吸附原子能在较低的电位下吸附氧,可显著提高1,2 丙二醇电催化氧化活性.与Pt电极相比较,Sb饱和吸附原子修饰的Pt电极使1,2 丙二醇氧化的峰电流增加了近2倍.作者还从表面质量变化提供了吸附原子电催化作用的新数据.

负载氧化物的γ-Al_2O_3粒子电极制备及电催化氧化性能研究

采用浸渍-焙烧法制备一系列不同的负载Cu、Pb和Sn的氧化物为负载层的粒子电极,应用于三维电极法处理工业印染废水研究,通过正交试验设计确定γ-Al2O3负载氧化物粒子电极制备的主要影响因素及最佳制备条件。结果表明:当焙烧时间为6 h,焙烧温度为550℃,浸渍液为四氯化锡,投加量为140 g时,电催化氧化处理印染废水效果最好:COD Cr去除率达到88.33%,色度去除率达到99.41%;并将该条件下制备的粒子进行SEM、XRD检测表征其形貌及晶相组成,结果表明其电催化活性高,稳定性好。

Cu基非晶合金表面结构调控及电催化氧化性能研究

通过调控氢氟酸浓度、腐蚀时间在Cu基非晶合金表面制备出均匀多孔层结构,进而提高其电催化氧化性能,开发出高活性,低成本催化剂。采用X射线衍射及电子能谱对非晶合金条带进行结构表征与成分分析,使用扫描电子显微镜观察腐蚀后条带表面形貌变化,使用电化学工作站对Cu基非晶合金进行循环伏安和计时电流测试,研究腐蚀工艺参数及添加Ni对Cu基非晶合金电催化氧化性能影响。结果表明,HF处理对于Cu基非晶具有活化作用;其对甲醇的电催化氧化作用随腐蚀液浓度的增大和腐蚀时间的延长,呈先增大后减小趋势;改变合金成分,添加Ni元素有助于提高其电催化氧化性能。

氧化铝粒子电极改性的研究

运用浸渍烧结法制备了以Sn氧化物为负载物质的粒子电极,并应用于三维电极法处理模拟甲基橙废水研究,采用正交测试设计确定了粒子电极负载氧化物的最佳制备条件和主要影响因素。结果表明:当焙烧温度为550℃、焙烧时间为6 h、浸渍液为四氯化锡0.1 mol·L^(-1)、浸渍时间为6 h时,染废水效果最好,COD去除率达到60.18%,染料去除率达到80.38%,表明体系降解甲基橙废水性能良好。

Electrosynthesis and physicochemical properties ofα-PbO_2-CeO_2-TiO_2 composite electrodes

In order to investigate the effect of solid particles dopants on physicochemical properties of α-PbO2 electrodes, a-PbO2 composite electrodes doped with nano-TiO2 and nano-CeO2 particles were respectively prepared on A1/conductive coating electrodes in 4 mol/L NaOH solution with addition of PbO until saturation by anodic codeposition. The electrodeposition mechanism, morphology, composition and structure of the composite electrodes were characterized by cyclic voltarnmogram （CV）, SEM, EDAX and XRD. Results show that the doping solid particles can not change reaction mechanism of α-PbO2 electrode in alkaline or acid plating bath, but can improve deposition rate and reduce oxygen evolution potential. The doping solid particles can inhibit the growth of a-PbO2 unit cell and improve specific surface area. The diffraction peak intensity of a-PbO2-CeO2-TiO2 composite electrode is lower than that of pure a-PbO2 electrode. The electrocatalytic activity of a-PbO2-2.12%CEO2-3.71%TIO2 composite electrode is the best. The Guglielmi model for CeO2 and TiO2 codeposition with a-PbO2 is also pronosed.

Enhanced electrocatalytic activity for H_2O_2 production by the oxygen reduction reaction: Rational control of the structure and composition of multi-walled carbon nanotubes

Hydrogen peroxide(H2O2)is a very useful chemical reagent,but the current industrial methods for its production suffer from serious energy consumption problems.Using high-activity and high-selectivity catalysts to electrocatalyze the oxygen reduction reaction(ORR)through a two-electron(2e^-)pathway is a very promising route to produce H2O2.In this work,we obtained partially oxidized multi-walled carbon nanotubes(MWCNTs)with controlled structure and composition by oxidation with concentrated sulfate and potassium permanganate at 40℃ for 1 h(O-CNTs-40-1).The outer layers of O-CNTs-40-1 are damaged with defects and oxygen-containing functional groups,while the inner layers are maintained intact.The optimized structure and composition of the partially oxidized MWCNTs ensure that O-CNTs-40-1 possesses both a sufficient number of catalytic sites and good conductivity.The results of rotating ring disk electrode measurements reveal that,among all oxidized MWCNTs,O-CNTs-40-1 shows the greatest improvement in hydrogen peroxide selectivity(from ~ 30% to ~ 50%)and electron transfer number(from ~ 3.4 to ~ 3.0)compared to those of the raw MWCNTs.The results of electrochemical impedance spectroscopy measurements indicate that both the charge-transfer and intrinsic resistances of O-CNTs-40-1 are lower than those of the raw MWCNTs and of the other oxidized MWCNTs.Finally,direct tests of the H2O2 production confirm the greatly improved catalytic activity of O-CNTs-40-1 relative to that of the raw MWCNTs.

Facile synthesis of 3D nanoporous Pd/Co_2O_3 composites with enhanced catalytic performance for methanol oxidation

To simultaneously reduce noble metal Pd usage and enhance electrocatalytic performance for methanol oxidation,Pd/Co2O3 composites with ultrafine three-dimensional(3D)nanoporous structures were designed and synthesized by simple one-step dealloying of a melt-spun Al-Pd-Co alloy with an alkaline solution.Their electrocatalytic activity in alkaline media was determined by a Versa-STAT MC workstation.The results indicate that the typical sizes of the ligaments and pores of the composites were approximately 8-9 nm.The Co2O3 was uniformly distributed on the Pd ligament surface.Among the as-prepared samples,the nanoporous Pd/Co2O3 composite generated from dealloying of the Al84.5Pd15Co0.5 alloy had the best electrocatalytic activity,and its activity was enhanced by approximately 230%compared with the nanoporous Pd from dealloying of Al85Pd15.The improvement of the electrocatalytic performance was mainly attributed to the electronic modification effect between Pd and Co as well as the bifunctional mechanism between Pd and Co2O3.

Mesoporous Co3O4 as an electrocatalyst for water oxidation

MesoporousCo3O4 has been prepared using porous silica as a hard template via a nanocasting route and its electrocatalytic properties were investigated as an oxygen evolution catalyst for the electrolysis of water. The ordered mesostructured Co3O4 shows dramatically increased catalytic activity compared to that of bulk Co3O4. Enhanced catalytic activity was achieved with high porosity and surface area, and the water oxidation overpotential （η） of the ordered mesoporous Co3O4 decreases significantly as the surface area increases. The mesoporous Co3O4 also shows excellent structural stability in alkaline media. After 100 min under 0.8 V （versus Ag/AgC1） applied bias, the sample maintains the ordered mesoporous structure with little deactivation of the catalytic properties.

Bimetallic oxide coupled with B-doped graphene as highly efficient electrocatalyst for oxygen evolution reaction

Developing electrocatalysts with high performance and low cost for the oxygen evolution reaction(OER)is of great importance for fabricating renewable energy storage and conversion devices.Here,a series of boron-doped graphene(BG)-supported bimetallic oxides of Co and Ni were obtained and served as OER electrocatalysts.Surprisingly,the annealed Co-Ni-Ox/BG with a Co/Ni ratio of 1:1 exhibits high performance toward oxygen evolution in alkaline electrolyte.The overpotential is only 310 mV at the current density of 10 mA cm-2,superior to many mono-metallic oxides reported before,and even comparable to the commercial RuO2.The regulation of charge distribution in bimetallic oxides and the strong synergistic coupling effects together contribute to the superior electrocatalytic performance of the Co-Ni-Ox/BG toward OER.This study also offers several effective ways to design high-performance OER electrocatalysts for water splitting.

Preparation and electrocatalytic properties of triuranium octoxide supported on reduced graphene oxide

Triuranium octoxide-reduced graphene oxide （U3O8/rGO） hybrids have been prepared by a two-step solution-phase method. The presence of GO is essential in order to obtain pure phase U3O8. The U3O8/rGO hybrids exhibited excellent electrocatalytic activity for the oxygen reduction reaction. The electron transfer number was calculated to be -3.9 at -0.7 V （vs. Ag/AgCl） from the slope of the Koutecky-Levich plots. The U3O8/rGO hybrids were more stable than commercial Pt/C catalysts. Furthermore, when methanol was present, the U3O8/rGO hybrids still retained high activity. In addition, the UBO8/rGO hybrids can also catalyze the reduction of hydrogen peroxide.

Greatly promoted oxygen reduction reaction activity of solid catalysts by regulating the stability of superoxide in metal-O_(2)batteries

Oxygen reduction reactions(ORRs)with one-or two-electron-transfer pathways are the essential process for aprotic metal-oxygen batteries,in which the stability of superoxide intermediates/products(O_(2)^(-),LiO_(2),NaO_(2),etc.)mainly dominates the ORR activity/stability and battery performance.However,little success in regulating the stability of the superoxides has been achieved due to their highly reactive characteristics.Herein,we identified and modulated the stability of superoxides by introducing anthraquinone derivatives as cocatalysts which functioned as superoxide trapper adsorbing the superoxides generated via surface-mediated ORR and then transferring them from the solid catalyst surface into electrolyte.Among the studied trappers,1,4-difluoroanthraquinone(DFAQ)with electron-withdrawing groups showed the highest adsorption towards superoxides and could efficiently stabilize LiO_(2)in electrolyte,which greatly promoted the surface-mediated ORR rate and stability.This highlighted the magnitude of adsorption between the trapper and LiO_(2)on the ORR activity/stability.Using an aprotic Li-O_(2)battery as a model metal-O_(2)battery,the overall performance of the cell with DFAQ was substantially improved in terms of cell capacity,rate capability and cyclic stability.These results represent a significant advance in the understanding of ORR mechanisms and promoting the performance of metal-O_(2)batteries.