氧化还原功能纤维的研究──含醇胺基纤维的制备及其与Au^（3＋）的氧化还原吸附反应

用二乙醇胺、乙醇胺及三乙醇胺与反应性氯甲基化纤维进行胺化反应，得到的功能纤维Ⅰ、Ⅱ和Ⅲ的含氮量分别为２．２６、２．７１和１．８６ｍｍｏ１／ｇ．吸附实验结果表明，纤维Ⅰ、Ⅱ和Ⅲ对Ａｕ^（３＋）的最大吸附量分别为５５０、６２０、４０９ｍｇ／ｇ，且能将部分吸附态Ａｕ^（３＋）还原成单质金．通过元素分析、红外光谱、核磁共振谱以及光电子能谱证实纤维中与氮原子相邻的羟基碳原子先被氧化成了羰基而氮原子未被氧化．

氧化还原功能纤维的研究(IV)——含醇胺基功能纤维对Au^(3+)的氧化还原反应机理

通过元素分析、红外光谱、广角Ｘ－射线衍射、核磁共振波谱及光电子能谱等分析手段证实含醇胺基功纤维与Ａｕ３＋的氧化还原反应过程中，约有３３％的吸附态金被还原成单质，纤维上约有５．７％Ｃ＝Ｏ键形成，而氮原子未被氧化．即纤维上氮原子附近的羟基碳原子先被氧化生成了羰基．同时以氯甲基化纤维为基体的三甲胺基纤维对Ａｕ３＋无还原作用。

氧化还原功能纤维的研究（Ⅲ）──含醇胺基纤维的制备及其对Au^（3＋）的吸附性能

用二乙醇胺、乙醇胺及三乙醇胺与反应性氯甲基化纤维进行胺化反应，得到含氮量分别为２．２６、２．７１、１．８６ｍｍｏｌ／ｇ的功能纤维（编号依次为Ⅰ、Ⅱ、Ⅲ）．静态吸附实验结果表明，纤维Ⅰ在ｐＨ＝２．５对Ａｎ３＋的吸附量达最大（５５０ｍｇ／ｇ），纤维Ⅱ和Ⅲ在ｐＨ＝２．０对Ａｎ３＋的吸附量分别为６２０和４０９ｍｇ／ｇ它们都能将部分吸附态Ａｎ３＋还原成单质．纤维Ⅰ对吸附态Ａｎ３＋的还原百分率随ｐＨ值的升高而提高，ｐＨ。５．０时达８７％．ｐＨ＝２．０时纤维Ⅱ和Ⅲ对Ａｎ３＋的还原百分率达１００％；纤维Ⅰ、Ⅱ对Ａｎ３＋的吸附量随溶液温度升高而提高，另外，随溶液离子强度升高纤维Ⅰ对Ａｎ３＋的吸附量减小；在非水介质中，纤维Ⅰ、Ⅱ对Ａｕ３＋的吸附量比在水中小，但也能将部分吸附态金属离子还原成单质．吸附动力学实验结果表明，纤维Ⅰ对Ａｕ３＋的吸附在５０ｍｉｎ可达饱和吸附量的一半（即ｔ１／２＝５０ｍｉｎ）．用扫描电子显微镜观察到吸附在纤维Ⅰ上的金聚集成粒状．

热塑性纤维素与PVA混溶性的分子动力学模拟

首次提出了将氧化还原改性纤维素(Oxidation-reduction modified cellulose,ORC)与聚乙烯醇(Poly(vinyl alcohol),PVA)共混进行制备复合材料,并采用分子动力学模拟研究了ORC与PVA的混溶性.对分子链间相互作用能和氢键数量分析发现,随着改性程度增加,ORC与PVA会产生更强烈的相互作用,这促进了组分间的混溶.当ORC的改性程度达到40%后,ORC与PVA的溶解度参数差值为2.02(J/cm^(3))^(1/2),达到混溶条件.根据Flory-Huggins理论确定了醇解度为88%和99%的PVA与ORC的混溶性,结果表明PVA(88%)与ORC的混溶性更好.对共混体系中形成氢键原子的径向分布函数分析发现,醋酸乙烯酯重复单元上的羰基更倾向与ORC形成分子链间氢键,而乙烯醇重复单元上的羟基更倾向形成分子链内氢键,这促使PVA(88%)/ORC共混体系中形成更多的分子链间氢键,从而混溶性更好.研究结果可为ORC/PVA复合材料的制备提供理论指导.

Electrochemical performance of interfacially polymerized polyaniline nanofibres as electrode materials for non-aqueous redox supercapacitors

H+ doped polyaniline nanofibre(PH) was synthesized by interfacial polymerization and polyanilines doped with Li salt(PLI and PHLI) were prepared by immersing emeraldine base(EB) and H+ doped polyaniline in 1 mol/L LiPF6/(EC-EMC-DMC),respectively.PH,PLI and PHLI were all characterized by scanning electron microscopy(SEM) and Fourier transform infrared(FT-IR) spectrometry.With 1 mol/L LiPF6/(EC-EMC-DMC) as electrolyte,PH,PHLI and PLI were used as the active materials of symmetric non-aqueous redox supercapacitors.PLI shows the highest initial specific capacitance of 120 F/g(47 F/g for PH and 66 F/g for PHLI) among three samples.After 500 cycles,the specific capacitance of PLI remains 75 F/g,indicating the good cycleability.

Kinetics of reductive leaching of manganese oxide ore using cellulose as reductant

The kinetics of reductive leaching of manganese from a low-grade manganese oxide ore were studied using cellulose as reductant in dilute sulfuric acid medium.It was found that when the stirring speed was higher than 200 r/min,the effect of gas film diffusion on manganese extraction efficiency could be neglected,and the kinetic behavior was investigated under the condition of elimination of external diffusion influence on the leaching process.Effects of leaching temperature,mass ratio of cellulose and ore,and the sulfuric acid concentration on manganese extraction efficiency were discussed.The kinetic data were analyzed based on the shrinking core model,which indicated that the leaching process was dominated by both ash layer diffusion and chemical reaction at the initial stage,with the progress of leaching reaction,the rate-controlling step switched to the ash layer diffusion.It was also concluded that the sulfuric acid concentration had the most significant influence on the leaching rate,the reaction orders with respect to the sulfuric acid concentration were 2.102 in the first 60 min,and 3.642 in the later 90 min,while the reaction orders for mass ratio of cellulose and ore were 0.660 and 0.724,respectively.An Arrhenius relationship was used to relate the temperature to the rate of leaching,from which apparent activation energies were calculated to be 46.487 kJ/mol and 62.290 kJ/mol at the two stages,respectively.Finally,the overall leaching rate equations for the manganese dissolution reaction with cellulose in sulphuric acid solution were developed.The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of SEM and XRD analyses.

2,3-二醛基纤维素还原反应条件的优化及产物表征

利用高碘酸钠选择性氧化微晶纤维素,制备了氧化度(DO)为1.588的2,3-二醛基纤维素(DAC)。醛基在一定条件下可转换为羟基,本研究以硼氢化钠为还原剂,采用Box-Behnken方法对研究的变量进行响应曲面建模,以反应时间、固液比、反应温度为变量,以产物还原2,3-二醛基纤维素(R-DAC)的DO为因变量,优化R-DAC的制备条件。ANOVA证实了数学模型的充分性。结果表明:在优化条件下,可制备氧化度接近于0的R-DAC。采用红外光谱、同步热分析仪、X射线衍射仪等对R-DAC的结构、热稳定性、结晶性等进行了表征。

N‐doped porous carbon nanofibers inlaid with hollow Co_(3)O_(4) nanoparticles as an efficient bifunctional catalyst for rechargeable Li‐O_(2) batteries

Stable and high‐efficiency bifunctional catalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desired for the practical application of Li‐O_(2)batteries with excellent rate performance and cycle stability.Herein,a novel hybrid bifunctional catalyst with carbon nanofibers inlaid with hollow Co_(3)O_(4)nanoparticles and separate active sites for ORR and OER were prepared and applied in Li‐O_(2)batteries.Benefiting from the synergistic effect of unique porous structural features and high electrocatalytic activity of hollow Co3O4 intimately bound to N‐doped carbon nanofibers,the assembled Li‐O_(2)batteries with novel catalyst exhibited high specific capacity,excellent rate capability,and cycle stability up to 150 cycles under a capacity limitation of 500 mAh g^(–1)at a current density of 100 mA g^(–1).The facile synthesis and preliminary results in this work show the as‐prepared catalyst as a promising bifunctional electrocatalyst for applications in metal‐air batteries,fuel cells,and electrocatalysis.

Encapsulated MnO in N-doping carbon nanofibers as efficient ORR electrocatalysts

Development of cheap,abundant and noblemetal-free materials as high efficient oxygen reduction electrocatalysts is crucial for future energy storage system. Here,one-dimensional（1D） MnO N-doped carbon nanofibers（MnO-NCNFs） were successfully developed by electrospinning combined with high temperature pyrolysis. The MnO-NCNFs exhibit promising electrochemical performance,methanol tolerance,and durability in alkaline medium. The outstanding electrocatalytic activity is mainly attributed to several issues.First of all,the uniform 1D fiber structure and the conductive network could facilitate the electron transport. Besides,the introduction of Mn into the precursor can catalyze the transformation of amorphous carbon to graphite carbon,while the improved graphitization means better conductivity,beneficial for the enhancement of catalytic activity for oxygen reduction reaction（ORR）. Furthermore,the porous structure and high surface area can effectively decrease the mass transport resistance and increase the exposed ORR active sites,thus improve utilization efficiency and raise the quantity of exposed ORR active sites. The synergistic effect of MnO and NCNFs matrix,which enhances charge transfer,adsorbent transport,and delivers efficiency in the electrolyte solution,ensures the high ORR performance of MnO-NCNFs.

Bacterial cellulose-regulated synthesis of metallic Ni catalysts for high-efficiency electrosynthesis of hydrogen peroxide

The decentralized production of H_(2)O_(2) via a twoelectron oxygen reduction reaction(2e^(-)ORR)has emerged as a promising alternative to the energy-intensive anthraquinone(AQ)process.However,its practical application requires 2eORR electrocatalysts with high activity and selectivity.Herein,we report the synthesis of metallic Ni nanoparticles anchored on bacterial cellulose-derived carbon fibers(Ni-NPs/BCCF)via a facile impregnation-pyrolysis method as efficient electrocatalysts for 2 e-ORR to H_(2)O_(2).By tuning the amount of Ni precursor,the best electrocatalytic performance toward 2 eORR was achieved for Ni-NPs/BCCF-20.7,affording a high H_(2)O_(2) selectivity of ~90% and an onset potential of 0.75 V vs.reversible hydrogen electrode(RHE)in an alkaline electrolyte.Ni-NPs/BCCF-20.7 achieved the largest H_(2)O_(2) yield rate of 162.7±13.7 mmol gcat^(-1)h^(-1) and the highest Faradaic efficiency of 93.9%±4.2% at 0.2 and 0.5 V vs.RHE from the bulk ORR system,respectively.Theoretical calculations revealed the more favorable"end-on"adsorption configuration of molecular oxygen on the exposed Ni(111)plane,which can effectively suppress the O-O bond dissociation,resulting in high selectivity for H_(2)O_(2) generation.