用循环伏安法研究烷氧基聚紫精的电氧化还原性能

利用循环伏安法研究了烷氧基聚紫精(PAoV)的电氧化还原性能,测定了它们的两步还原电位、峰电流和表现扩散系数(D),结果表明:D随着PAoV结构中所含醚键的增加而减小;并对第一步还原反应的可逆性进行了研究,发现第一步还原反应的可逆性优于第二步还原反应,同时证明电极反应是由扩散步骤控制的;PAoV具有良好的抗电疲劳性能;并研究了体系pH值和扫描范围对PAoV的电氧化还原性能的影响。

铜纤维毡的模板-热还原法制备及二氧化碳电还原性能

为了研究人工碳纳米材料模板对铜纤维毡制备及结构的影响,应用模板-热还原法,以3种碳材料为模板,通过优化前驱体中CuCl_(2)·2H_(2)O与模板的质量比尝试制备铜纤维毡。使用X射线衍射仪、扫描电子显微镜和能量色散谱仪分析了试样的结构和化学组成。结果表明,石墨烯可发挥模板作用,得到橙红色厘米级铜纤维毡,铜纤维毡中铜纤维的直径约5μm,且铜纤维表面分布亚微米级台阶。将铜纤维毡制成自支撑电极,应用在线气相色谱仪和核磁共振波谱仪评价了铜纤维毡的CO_(2)电化学还原性能。相对于泡沫铜,铜纤维毡作为CO_(2)电还原反应的催化剂,展现了对甲酸生成较高的选择性。

Carbon Foam Anode Modified by Urea and Its Higher Electrochemical Performance in Marine Benthic Microbial Fuel Cell

Electrode materials have an important effect on the property of microbial fuel cell(MFC). Carbon foam is utilized as an anode and further modified by urea to improve its performance in marine benthic microbial fuel cell(BMFC) with higher voltage and output power. The electrochemical properties of plain carbon foam(PC) and urea-modified carbon foam(UC) are measured respectively. Results show that the UC obtains better wettability after its modification and higher anti-polarization ability than the PC. A novel phenomenon has been found that the electrical potential of the modified UC anode is nearly 100 m V lower than that of the PC, reaching-570 ±10 m V(vs. SCE), and that it also has a much higher electron transfer kinetic activity, reaching 9399.4 m W m-2, which is 566.2-fold higher than that from plain graphite anode(PG). The fuel cell containing the UC anode has the maximum power density(256.0 m W m-2) among the three different BMFCs. Urea would enhance the bacteria biofilm formation with a more diverse microbial community and maintain more electrons, leading to a lower anodic redox potential and higher power output. The paper primarily analyzes why the electrical potential of the modified anode becomes much lower than that of others after urea modification. These results can be utilized to construct a novel BMFC with higher output power and to design the conditioner of voltage booster with a higher conversion ratio. Finally, the carbon foam with a bigger pore size would be a potential anodic material in conventional MFC.

Oxygen Electroreduction Performance of Ultrasmall Gold Nanoclusters

Ultrasmall gold nanoclusters consisting of 2-4 Au atoms were synthesized and their per- formance in electrocatalytic oxygen reduction reactions （ORR） was examined. These clus- ters were synthesized by exposing AuPPh3Cl to the aqueous ammonia medium for one week. Electrospray ionization mass spectrometry （ESI-MS）, X-ray absorption fihe struc- ture （XAFS）, and X-ray photoelectron spectroscopy （XPS） analyses indicate that the as- synthesized gold clusters （abbreviated as Aux） consist of 2-4 Au atoms coordinated by the triphenylphosphine, hydroxyl, and adsorbed oxygen ligands. A glassy carbon disk electrode loaded with the Aux clusters （Aux/GC） was characterized by the cyclic and linear-sweep voltammetry for ORR. The cyclic voltammogram vs. RHE shows the onset potential of 0.87 V, and the kinetic parameters of JK at 0.47 V and the electron-transfer mmlber per oxygen molecule were calculated to be 14.28 mA/cm2 and 3.96 via the Koutecky-Levich equations, respectively.

TEMPO-substituted polyacrylamide for an aqueous electrolyte-typed and organic-based rechargeable device

A hydrophilic radical polymer, poly（2,2,6,6-teteramethylpiperidinyloxyl-4-yl acrylamide） （PTAm）, was synthesized via oxidation of the corresponding precursor polymer, poly（2,2,6,6-teteramethylpiperidine-4-yl acrylamide）. Electrochemical properties of the PTAm layer were characterized in three aqueous electrolytes of sodium chloride （NaCl）, sodium tetrafluoroborate （NaBF4）, and sodium hexafluorophosphate （NaPF6） to optimize its activity as an organic cathode. The counter anion species significantly affected the capacity and the cycle performance of the PTAm layer. The PTAm layer in the presence of BF4？ displayed quantitative redox capacity beyond 1 μm layer thickness and maintained the discharging capacity of 110 mAh g-1 （97% vs. the calculated capacity） even after 1000 cycle charging/discharging, which could be ascribed to its appropriate affinity to the aqueous electrolyte without any dissolution into the electrolyte. A totally organic-based rechargeable cell was fabricated using PTAm and poly（N-4,4＇-bipyridinium-N-decamethylene dibromide） as the cathode and the anode, respectively, and the aqueous electrolyte of NaBF4. The cell gave a plateau voltage at 1.2 V both on charging and discharging and an excellent charging/discharging cyclability of ＆gt;2000 with high coulombic efficiency of ＆gt;95%.

Towards unlocking high-performance of supercapacitors: From layered transition-metal hydroxide electrode to redox electrolyte.

Both energy density and power density are crucial for a supereapacitor device, where the trade-off must be made between the two factors towards a practical application. Herein we focus on pseudocapacitance produced from the electrode and the electrolyte of supercapacitors to simultaneously achieve high energy density and power density. On the one hand, layered transition metal hydroxides （Ni（OH）2 and Co（OH）,,） are introduced as electrodes, followed with exploration of the effect of the active materials and the substrate on the electrochemical behavior. On the other hand, various redox electrolytes are utilized to improve the specific capacitance of an electrolyte. The roadmap is to select an appropriate electrode and a dedicated electrolyte in order to achieve high electrochemical performance of the supercapacitors.

Two-dimensional titanium carbide MXenes as efficient non-noble metal electrocatalysts for oxygen reduction reaction

MXenes, a new family of multifunctional two dimensional(2D) solid crystals integrating high electroconductivity and rich surface chemistries, are promising candidates for electrolysis, which, however, have rarely been reported. Herein, free-standing ultrathin 2D MXene nanosheets were successfully fabricated from bulky and rigid MAX phase ceramics by liquid exfoliation with HF etching(delamination) and TPAOH intercalation(disintegration).The high oxygen reduction reaction(ORR) performance has been obtained, due to the extremely small thickness of the asfabricated Ti3C2 around 0.5–2.0 nm, equivalent to the dimensions of single-layer or double-layer Ti3C2 nanosheets in thickness. The ORR performance of the obtained Ti3C2 MXene-based catalyst exhibits desirable activity and stability in alkaline media. This study demonstrates the potential of earth-abundant 2D MXenes for constructing high-performance and cost-effective electrocatalysts.

Rational design of viologen redox additives for high-performance supercapacitors with organic electrolytes

Introducing redox species into the electrolytes of traditional electric double layer capacitors(EDLCs)is an efficient strategy to enhance their energy density owing to Faradic reactions.However,few studies have elucidated the effect of the molecular structures of organic redox species on the performance of relative supercapacitors,which is important in the development of redox additives for super-capacitors.In this context,we synthesized several viologens and used them as new organic redox additives for super-capacitors with organic electrolytes.The detailed experimental analysis and theoretical calculation results show that the electrochemical performance of viologens relies heavily on their side chains and conjugated cores.Specifically,the side chains of the viologens affect their electronic structures and are consistent with behaviours between the molecules and the electrode pores due to the size effect,thus influencing their specific capacities.In addition,a larger conjugated aromatic core endows viologens with a smaller band gap and a higher degree of electron delocalization,resulting in better rate performance and cycling stability.Consequently,aπ-conjugated viologen derivative is selected as a favourable additive and enables an EDLC-type supercapacitor to exhibit a high energy density(34.0 W h kg^−1 at 856 W kg^−1)and good cycling performance.

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.

Synthesis and Electrocatalytic Oxygen Reduction Properties of Truncated Octahedral Pt3Ni Nanoparticles

Pt3Ni nanoparticles have been obtained by shape-controlled synthesis and employed as oxygen reduction electrocatalysts for proton exchange membrane fuel cells （PEMFC）. The effects of varying the synthesis parameters such as the types of the capping agent and the reducing agent, and the reaction time have been systematically studied. The as-prepared PtBNi nanoparticles were subjected to a butylamine-based surface treatment in order to prepare carbon-supported electrocatalysts. The Pt3Ni electrocatalysts show an area- specific activity of 0.76 mA/cm2（pt） at 0.9 V in an alkaline electrolyte, which is 4.5 times that of a commercial Pt/C catalyst （0.17 mA/cm2 （Pt））. The mass activity reached 0.30 A/mg（Pt） at 0.9 V, which is about twice that of the commercial Pt/C catalyst. Our results also show that the area-specific activities of these carbon-supported Pt3Ni electrocatalysts depend strongly on the （111） surface fraction, which is consistent with the results of a study based on Pt3Ni extended single-crystal surfaces.

Facile synthesis of nickel cobalt selenide hollow nanospheres as efficient bifunctional electrocatalyst for rechargeable Zn-air battery

Designing high active,low cost and bifunctional electrocatalysts is urgent for developing clean energy storage and conversion systems.Transition metal selenides exhibit optimal electronic conductivity and tunable physicochemical properties,which endow them with potential for efficient electrocatalysts to facilitate the oxygen reduction and oxygen evolution reactions(ORR and OER).Herein,hollow NixCo0.85-xSe nanospheres were synthesized using a facile polyol based solution chemical method.The NixCo0.85-xSe exhibits an onset overpotential of 0.89 V for ORR,and an overpotential of 305 mV to achieve 10 mA cm^-2 for OER.Moreover,the NixCo0.85-xSe based Zn-air battery displays remarkable specific capacity and durability.Such superior catalytic performances can be attributed to the synergistic effect,large specific surface area and enhanced electron transfer rate.This approach provides a new way to design highly efficient bifunctional electrocatalysts for electrochemical energy storage and utilization.