Mechanism investigation and suppression of self-discharge in active electrolyte enhanced supercapacitors

National Natural Science Foundation of China [21104041]The self-discharge (SDC) process of active electrolyte enhanced supercapacitors (AEESCs) was investigated systematically. The AEESC with hydroquinone as an active electrolyte showed higher specific capacitance but much faster SDC compared with electronic double layer supercapacitors. The electrode process of the above AEESC was studied, and the mechanism of the SDC process was investigated quantitatively. The migration of the active electrolyte between two electrodes of the device was found to be the primary reason for the fast SDC. Two strategies were designed to suppress the migration of the active electrolyte. Following these strategies, two new AEESCs were fabricated, with a Nafion (R) membrane as the separator and CuSO4 as the active electrolyte. The two AEESCs showed both high specific capacitances and longer SDC times, demonstrating that the problem of poor energy retention of AEESCs was successfully solved

Basic aluminum sulfate@graphene hydrogel composites: preparation and application for removal of fluoride

National Natural Science Foundation of China [21104041]Porous composites based on basic aluminum sulfate and graphene hydrogel (BAS@GHG) were prepared via homogeneous precipitation of BAS in GHG, and used as adsorbents for fluoride removal from water. The BAS@GHG composites have a porous structure with a chemically converted graphene three dimensional network coated by a thin layer of amorphous BAS. These composites showed high adsorption capacities of up to 33.4 mg g(-1) at equilibrium fluoride concentrations of 10.7 mg L-1 and temperatures of 298 K, higher than those of previously reported graphene and aluminum-based adsorbents. The adsorption kinetics and isotherm were analyzed by fitting experimental data with pseudo-first-order kinetics, the Weber-Morris model and Langmuir equations. The effects of temperature, pH value, and co-existing anions on the adsorption of fluoride were also investigated

Synthesis of metal nanoparticle@graphene hydrogel composites by substrate-enhanced electroless deposition and their application in electrochemical sensors

National Natural Science Foundation of China [21104041]In this paper, a green and facile method based on substrate-enhanced electroless deposition is designed for the fabrication of three-dimensional (3D) metal nanoparticle@ graphene hydrogel (MNP@GHG) composites. A galvanic cell was constructed by inducing nickel foam as the substrate of GHG, to enhance the deposition of MNPs via galvanic cell reaction. Various MNPs with redox potential higher than that of Ni, including Au, Pt, Pd and Cu, were successfully deposited onto GHG. The produced gold nanoparticles/GHG composite showed good electrocatalytic activity and was used to fabricate an amperometric sensor towards uric acid with good sensitivity

Electrochemical supercapacitor with polymeric active electrolyte

National Natural Science Foundation of China [21104041]An electrochemical supercapacitor with a polymeric active electrolyte was designed and fabricated in this work. A water-soluble conducting polymer, sulfonated polyaniline (SPAni), was used in the supercapacitor as the active electrolyte and a semipermeable membrane was employed as the separator of the device. It was found that SPAni in the electrolyte can provide pseudocapacitance via its reversible electrochemical redox reaction. Owing to the good stability of SPAni, the supercapacitor has a long cycling life. Moreover, the migration of SPAni between the two electrodes was blocked by the semipermeable membrane separator, thus self-discharge caused by the shuttle effect of SPAni was suppressed. The research in this paper demonstrates the possibility of using a polymer as the active electrolyte in a supercapacitor and has paved a new way to achieve active electrolyte enhanced supercapacitors with high capacitance and good energy retention

A case study of Kashi River: The change of temperature and precipitation near reservoir in the Tianshan Mountains of Xinjiang

在中国西北和西南的大型水电开发过程中，山区各个主要河流上都建造了大型水电工程。新疆天山山区，是新疆主要河流的发源地。 目前， 这些地区已经建成水电基地。而这些水库在高寒山区建立，与中国东部的水库产生的效应不同。本研究以新疆伊犁喀什河吉林台水电站为案例研究，通过站点数据、模式数据和遥感数据进行深入分析。在研究过程中，首先，以地面观测数据为真值，对本论文中使用的格点化模式数据和遥感数据进行评估。其次，使用蒙特卡洛方法重建百年时间内气温和降水， 明确流域内百年气候变化趋势，消除区域气候波动。再次，在相邻区域气候格局近似、 相邻时段气候格局相关的假说基础上，选取喀什河流域水库附近的尼勒克站作为代表站，与相邻站点建立线性和非线性关系的统计模型，分析水库建成对于尼勒克站的影响。随后，利用经过评估后的格点化降水数据分析水库建成前后的多年降水空间变化，分析水库建成后影响的区域。最终， 得出以下结论：1、在 CFSR 再分析数据、 CHIRPS 遥感降水数据、 PERSIANN-CDR 遥感降水数据和 MSWEP V1 多源融合降水数据评估工作中， 发现 MSWEP V1 降水数据在年际和年内的统计指标均优于其他三套降水数据。 在对 WRF 长时间区域气候模拟数据评估中，发现 WRF 输出的气温和降水数据在年际尺度上， WRF 模式年平均气温和年降水距平观测气温和降水的距平分布整体上趋势吻合较好。2、在百年尺度上，伊犁河流域的气温和降水都呈现增加的趋势，尤其是气温的增加趋势更加明显。而降水处于波动中增加。 伊犁河谷， 山区和平原地区1931~1960 年是百年间气温较低时期， 1991~2010 年是温度最高时期，山区和平原气温分别达到 1.4℃和 6.3℃。在年内尺度，盆地内山区冬季气温百年间变幅较大，夏季气温变幅较小。气温的增幅主要以冬季增幅为主。3、在站点尺度上， 2005 年水库建成后尼勒克的气温和降水，呈现显著的由水库引起的湖泊效应。在暖季，气温偏冷，冬季呈现不同程度的偏暖。对于降水，冬季相对于水库建成前增多，夏季减少。4、在尼勒克站，降雪事件主要发生在-5~2℃气温区间，而并不是气温越冷、降雪越多。 1985~2005 年区域的降雪量较多，而 2005~2008 年之间尼勒克及周边站点的降雪量均处于贫雪状态， 随后降雪增加。 而 2005 年这个突变是由水库修建而导致的区域气候突变现象。5、基于多源融合技术的 MSWEP 降水数据，反映出水库的修建对于喀什河上游的影响较大，降水呈现增加现象，而在下游降水在全年、冷季和暖季都存在不同程度降水减少现象

Graphene Oxide Self-assembled Hydrogels

氧化石墨烯(gO)是化学氧化-还原法制备石墨烯的中间体,也是除石墨烯以外最为重要的二维纳米材料.由于gO纳米片表面富含各种含氧基团,因此其在水溶液中可以与多种物质发生超分子自组装,形成水凝胶.本文在分析gO化学结构的基础上,总结gO水凝胶的制备方法和形成机理,着重讨论gO的拓扑形状对水凝胶形成的影响,以及促进gO形成凝胶的超分子作用力,包括氢键、静电作用、配位作用、π-π作用等.最后,对gO自组装水凝胶的应用进行了评述,并展望了该领域今后的发展方向.Graphene oxide(GO)is the precursor of chemically converted graphene,and also a very important two-dimensional nanomaterial.Owing to the various oxygen-containing functional groups on GO sheets,GO can form supramolecular hydrogels via threedimensional self-assembly with diverse substances.In this review,after elucidating the chemical structure of GO,we reviewed the preparation methods and formation mechanism of GO hydrogels.The effects of two-dimensional shape of GO,and the supramolecular interactions which were commonly used to crosslink GO hydrogels,including hydrogen bond,electrostatic interaction,coordination andπ-πinteraction,were discussed comprehensively.Finally,the applications of graphene hydrogels were summarized,and future prospect in this area was also described.国家自然科学基金(21104041

风洞洞壁对风力机翼型气动特性的影响分析

本文通过风洞试验测量和计算流体动力学（ComputationalFluidDynamics，CFD）数值模拟的研究结果，分析了风洞洞壁对风力机翼型气动特性的影响．试验风洞为中国科学院工程热物理研究所（InstituteofEngineeringThermophysics，IET）低速回流风洞，所选用的翼型为DU91-W2-250．数值模拟采用有洞壁、无洞壁、无侧壁三种方式进行计算，通过对比试验和数值计算结果验证了采用CFD数值模拟分析风力机翼型洞壁效应的可行性．通过数值模拟分析并与经典映像法及Maskell洞壁修正方法对比，得出：风洞中，上下壁面的存在使流动在风洞壁面形成一定厚度的边界层，造成气流的通道面积减小，来流有效速度增加，并引起翼型升力系数CI和阻力系数Cd增加；风洞侧壁诱导翼型段表面的展向流动、抑制了翼型表面的流动分离，减小了翼型弦向流动速度，引起翼型升力系数减小，阻力系数增加；小攻角时风洞侧壁对翼型表面流动的影响可以忽略，翼段表面流动保持二维性，大攻角时风洞侧壁干扰效应显著，其影响程度超过风洞上下壁面，与无洞壁相比，风洞壁的存在使升力系数减小，阻力系数增加；经典映像法及Maskell方法因未考虑洞壁边界层的影响，并不适用于风力机翼型大攻角流动时的洞壁效应修正问题，大攻角修正时应考虑风洞侧壁影响，对升力系数给予增量；同时对于大攻角流动．翼型本身流动已不具有二维性．其气动性能的测量应采用多截面压力测量或天平测力方法

金刚石/铝导热复合材料的显微组织与热力学性能

以高温盐浴法对金刚石表面进行镀硅处理来改善金刚石和铝基之间的界面结合,镀硅后的金刚石颗粒表面略显粗糙,表面的镀层均匀;采用真空热压烧结法制备高导热镀硅金刚石/铝复合材料,研究了烧结温度和金刚石体积分数对复合材料相对密度和热导率的影响。随着金刚石体积分数的增加,复合材料的相对密度和热导均呈现先升后降的趋势,当金刚石体积分数为45%时,复合材料的热导率达到最大,为558 W/mK