SnO2 is widely used in perovskite solar cells(PSCs)due to its high electron mobility,suitable conduction band and low-temperature preparation characteristics.Currently,the two most commonly used methods for preparing SnO2 are SnCl2 hydrolysis oxidation or SnO2 sol-gel preparation.However,although SnCl2 hydrolysis oxidation can produce well-crystallized SnO2,its controllability is poor,resulting in low device performance repeat-ability.On the other hand,the devices based on SnO2 electronic transport layer prepared by the sol-gel method have good repeatability,but usually have poor crystallinity,leading to a decrease in electron transport performance.In this study,a combination of hydrolysis oxidation and sol-gel methods was used to prepare SnO2 electronic transport layers.The results of the study demonstrate that using SnCl2 hydrolysis oxidation to prepare high-quality SnO2 crystalline layers can serve as a pre-growth template to improve the crystalline quality of sol-gel generated SnO2.Additionally,covering the hydrolysis oxidation-based SnO2 layer with sol-gel prepared SnO2 crystalline layer can improves the repeatability of device preparation.The electron transport layers prepared by this method can effectively enhance the quality of thin film crystal growth and charge extraction capability,ultimately contributing to improving the efficiency,stability,and reducing hysteresis of the devices.
TiNi shape memory alloys have clear target demand in a variety of fields owing to their excellent struc-tural and functional properties.In this paper,focusing on B2 structural austenitic Ni-rich TiNi alloys,it is proposed to modulate the microstructure of the TiNi alloys through repeated cold rolling annealing,with an expectation to enhancing the lower mechanical strength and plastic deformation ability of the alloys.The dependence of the mechanical properties and microstructure of Ti48.9Ni50.9Zr0.2 and Ti47.9Ni51.9Zr0.2 alloys on cold rolling deformation and recrystallization annealing was systematically investigated.The tensile mechanical property tests show that the repeated cold rolling annealing can significantly enhance the overall mechanical properties of the alloys,in which the tensile strength of Ti48.9Ni50.9Zr0.2 alloy is increased from 550 MPa in the unrolled samples to 1 070 MPa after 6 passes of cold rolling annealing,and the elongation after fracture has grown from 4.9％to 10.0％.The EBSD,SEM and TEM microstructural observation reveals that the deformation and recrystallization structures of the alloy change alternately after multi-pass cold rolling and annealing,and the alloy grains are significantly refined and undergo an obvious preferred grain orientation.In addition,the basal texture of the alloy is further enhanced.The Ti2Ni and Ti3Ni4 precipitates are broken and refined during cold deformation,in which the nano-sized Ti3Ni4 pre-cipitate exhibits a favorable matching with matrix.Furthermore,stress-induced martensite as well as a large num-ber of high-density dislocations in the vicinity of the precipitation phases appear in the alloy.The mechanical pro-perties of alloys are strongly related to the microstructure,and the strengthening mechanisms can be understood by grain refinement strengthening,dislocation strengthening,precipitation strengthening and texture strengthening.
The light and high strength bamboo scrimber was buried in the core of concrete-filled steel tube (CFST) to form bamboo scrimber and concrete-filled steel tube column (BCFST), which was expected to reduce the amount of concrete and weight in CFST and promote the use of bamboo scrimber. To investigate the influences of key design parameters on the compressive performance, namely bamboo scrimber dimension, design concrete strength, and diameter to thickness of steel tube, ninety BCFSTs and eighteen CFSTs specimens were tested under axial compression. According to the experimental results, the improvement of the BCFST bearing capacity resulted from the contribution of the inner sandwich concrete and the bamboo scrimber under the constraint from the steel tube. The ultimate load rose with the increase of the bamboo scrimber dimension, concrete strength, and steel tube thickness. Note that the increase range of ultimate load of BCFSTs is 3.9% higher than that of CFSTs by increasing the dimension of bamboo scrimber, with a maximum increase at 43.9%. The damage modes of BCFSTs can generally be categorized into local buckling failure mode and shear failure mode. In addition, owing to the different compactness between the bamboo scrimber and the concrete, the stress-strain curve of the C80 concrete characterized the strain hardening tendency rather than the strain softening tendency in the C50 concrete. According to the load-strain curves of the BCFSTs and the contribution of the composite actions between the three parts of the member to the load-carrying capacity, the characteristic points were defined. A calculation model for accurately predicting the ultimate capacity of BCFSTs was proposed by considering the boundary conditions for both non built-in and fully built-in bamboo scrimber in CFSTs.
A series of Cu-BTC with different Polyvinylpyrrolidone (PVP) assisted amounts were pyrolyzed to prepare carbon supported copper and its oxides (CuOx/C without PVP and CuOx@PC with PVP) derivant. The structure of CuBTC and derivant was characterized by XRD, SEM, TEM, N2 adsorption isotherms et al., and the derivant was applied for oxidative carbonylation of methanol to dimethyl carbonate. The results show that the introduction of PVP is beneficial to improve the specific surface area of CuOx@PC and generate Cu-Cu2O heterojunctions. The activities of the catalysts containing Cu-Cu2O heterojunctions are higher than that of the catalysts without Cu-Cu2O. Compared with CuOx/C, the space-time yield of CuOx@PC-2 of dimethyl carbonate is significantly enhanced from 948 mg g-1 h-1 to 1295 mg g-1 h-1. Cu-Cu2O has a synergistic effect on the catalytic performance. The stability of the catalysts was evaluated. After eight cycles, the deactivation rate of CuOx@PC-2 (53 %) is lower than that of CuOx/C (74 %), because the aggregation of Cu is inhibited by the introduction of PVP. And the oxidation of Cu species is mainly responsible for the deactivation of the catalysts.
Hydrogel-based flexible polymer materials have received increasing attention due to their excellent sens-ing performance and superior ductility with application in smart wearable devices.However,the widespread use of intelligent wireless electronic wearables equipment has also produced severe electrical signals interference and ra-diation.The electrical signals interference generated by wearable devices significantly affects the performance of apparatuses.Therefore,it is important to develop hydrogel materials with dual functions of strain sensing and elec-tromagnetic shielding.This review begins with presenting on strain sensing and electromagnetic shielding mechan-ism of hydrogel materials.At the same time,the effects of microstructure,solvent type,conductive filler type and conductive network structure on the properties of bifunctional hydrogel materials are analyzed.Finally,according to the current research status of bifunctional hydrogels,the development direction and application prospect of bi-functional hydrogels are proposed.
Tumors are one of the leading causes of death in the world,and achieving precise and non-invasive effi-cient diagnosis and treatment of tumors is of great significance.We used carbon nanotubes(CNTs)with extremely high aspect ratio,easy to penetrate cell membrane and excellent biocompatibility as carriers,and acetylacetone iron as iron source,to synthesize magnetic carbon nanotube composite nanomaterials with excellent water disper-sion stability by in situ growing superparamagnetic ferric oxide nanoparticles(Fe3O4 NPs)on their surface through solvothermal method.The results showed that the magnetic carbon nanotubes had high near-infrared photo-thermal conversion performance,and could reach 48.6℃in 10 min under 808 nm laser irradiation at a concentra-tion of 50 µg·mL-1,and had good photothermal stability.Cell and imaging experiments showed that the composite nanomaterials had good biocompatibility and excellent photothermal killing effect on human cervical cancer cells(HeLa).In vitro simulated tumor microenvironment,the magnetic resonance imaging(MRI)T2 relaxation rate r2 of the magnetic carbon nanotubes was up to 215.61 mmol-1·L·s-1,indicating that the prepared magnetic carbon nanotubes had outstanding biosafety,magnetism and photothermal properties,and were expected to be applied to the integration of magnetic targeted tumor photothermal therapy and magnetic resonance imaging.
In this paper,the methods of wood cellulose skeleton extraction,densification technology and the re-search progress of functional application of wood film were systematically reviewed to provide theoretical basis and technical guidance for developing high-performance densified wood film and expanding its functional application.The characteristics of wood grading structure were summarized.The advantages and disadvantages of different methods to extract wood cellulose skeleton and the technological process of preparing densified wood film were compared.The application and research status of densified wood film at home and abroad were discussed.Densi-fied wood film can keep the natural directional skeleton structure of wood in the preparation process and reduce the problems of difficult degradation and energy consumption caused by polymer impregnation.It has broad ap-plication prospects in energy-saving building windows,flexible electronics base materials,acoustic diaphragms,photoelectric devices and other fields.Based on the unique hierarchical structure,low density,high strength and biodegradability of natural wood,the prepared densified wood film has a good development in its functional applic-ation field.However,according to the current research results and key problems in practical application,it is neces-sary to explore effective methods conducive to its large-scale production and provide research ideas for subsequent industrial development.
Fused deposition modeling(FDM)has become one of the most widely used additive manufacturing(AM)technologies due to its low cost and easy-to-preparation.Also,polylactic acid(PLA)has become the main raw ma-terial of FDM filament due to its good biodegradability and biocompatibility.However,the poor brittleness,tough-ness and heat resistance of PLA have seriously limited the large-scale application of its printing products.Therefore,adding one or more fillers into PLA filament is an important measure to alleviate its own shortcomings.Among them,biomass-based filler is an ideal choice.Adding biomass-based filler into PLA can not only effectively over-come the performance defects of the substrate,but also has good biodegradability and environmental friendliness.This paper reviews the research progress of PLA composites reinforced by the biomass-based filler through FDM printing in recent years.The influence of reinforcing fillers(such as wood powder,natural fiber,nanocellulose)with different size(from micrometer to nanometer)on the properties of PLA-based composites is investigated,which demonstrates the reasons for improving the properties of composites and the mechanism of interfacial compatibil-ity.Finally,the future development of FDM-printed PLA composites is prospected.
The effect of tensile performance degradation of glass fiber reinforced polymer(GFRP)bars on their bond performance with seawater sea-sand concrete(SSC)was studied.The tensile strength of a series of 10 mm GFRP bars was tested after immersing in simulated SSC pore solution at different temperatures for different durations.The bond performance of these degraded GFRP bars in SSC was conducted using the pull-out test.The failure mode,bond strength and the characteristics of the stress-slip curve were investigated.The test results indicate that the tensile strength of GFRP bars gradually decreases with the SSC pore solution immersion time.Compared with GFRP bars without immersion,the tensile strength of GFRP bars was reduced by 25％,29％ and 48％ after 3 months of immersion at 23℃,40℃ and 60℃,respectively.The bond strength reduces with the increase of the tensile per-formance degradation of GFRP bars.Compared with GFRP bars without immersion,their bond strength with SSC was reduced by 8％,19％a nd 38％ after 3 months of immersion at 23℃,40℃,and 60℃,respectively.
This article provides an overview of the research progress of upconversion composite materials in pho-tocatalysis.Due to the low utilization rate of solar radiation by traditional photocatalytic semiconductor materials,their practical application in environmental governance and energy conversion is limited.Upconversion composite materials can convert low-energy radiation into high-energy emission,improve the responsiveness of photo-catalysts to infrared-visible light,and thus improve the utilization rate of solar energy.This article first elaborates on the basic principles and application prospects of photocatalytic reactions and then focuses on the preparation methods,performance characteristics,advantages,and disadvantages of three types of upconversion composite photocatalysts:Rare earth,quantum dots,and triplet-triplet annihilation.It also introduces optimization strategies that use precious metals or alloys to enhance upconversion effects and charge separation efficiency with examples.The purpose of this article is to provide new ideas and references for photocatalysis research and promote the ap-plication and development of upconversion composite materials in the field of photocatalysis.
Carbon-based conductive materials are material systems with a carbon atom as the backbone,which have excellent properties such as structural diversity,highly tunable and high chemical stability.The introduction of carbon-based conductive materials into sensing and detection analysis can improve the signal strength of the sensor and increase the stability of the sensing and detection analysis.Sensors made from carbon-based conduct-ive materials offer higher sensitivity,lower detection limits and a wider linear range for the detection of analytes than sensors made from conventional materials.As a result,carbon-based conductive material-based detection and analysis technologies have shown great potential for application in various fields such as medical treatment,envir-onmental monitoring and food testing.The paper presents the classes of carbon-based conductive materials in terms of dimensions and the applications of their prepared sensors in sensing and detection analysis,presents the problems and challenges of carbon-based conductive materials and their prepared sensors in the detection of ana-lytes,and gives an outlook on the trends of future research.
Thermal interface materials could effectively transfer the heat from electronic devices with high temper-ature to the thermal management components,so as to alleviate the problems of deterioration of component life caused by overheating of electronic devices.In recent years,the polymer-based composites composed of polymer matrix and reinforcing fillers with high thermal conductivities have been widely concerned because of their low density and adjustable thermal conductivities.Different from the conventional composites with randomly dis-persed fillers,the construction of three-dimensional(3D)continuous network structure in the polymer matrix could significantly increase the filler/filler contact,reduce the percolation threshold of thermal conductivity and the interfacial thermal resistance,and then significantly improve the thermal conductivities of composites.Firstly,the thermal conductivity mechanisms of polymer-based thermal conductive composites were briefly analyzed.Secondly,the construction processes of polymer-based thermally conductive composites with interconnected net-work structures were summarized,mainly including the pre-construction of 3D thermally conductive filler network,the post-processing based on polymer particle/powder,the post-processing based on polymer fiber/fabric,and the film casting or flocculation based on polymer latex.The effects of different types of thermal conductive fillers on the thermal conductivities of polymer composites were summarized,mainly including metal fillers,ceramic fillers,carbon-based fillers and their hybrid fillers.Finally,the development prospects of polymer-based thermally con-ductive composites with interconnected network structures were prospected.
电子束原位固化迎合"双碳"战略下碳纤维增强树脂基复合材料(CFRP)低成本控形控性的一体化制造需求,但却因固化构件界面质量差而尚未迈向工业化.本文围绕电子束固化CFRP弱界面的高效、高工业可行性强化技术,探索了微波短时辐射改性碳纤维改善界面的机制及工艺,阐明了碳纤维表面物理形貌、粗糙度及化学成分在不同微波辐射工艺参数下的演变规律:碳纤维表面的粗糙度和表面积,由未改性时的4.41 nm和 7.5 nm2 最高提高至微波辐射 180 s后的 21.7 nm和 26.4 nm2;O/C原子比也由未改性时的 0.2578最高增至辐射 180 s时的 0.3278.进一步地,构建了界面分子动力学模型,从分子层面细化并深化了羧基及羟基强化界面的本质,及其对界面结构及界面能的影响.界面剪切强度测试结果表明,在微波辐射(90 s)的物理及化学改性双重作用下,碳纤维/树脂界面获得了 20.47%的提高.该研究为高性能电子束固化CFRP的绿色成型制造提供基础与支撑,具有重要的科学意义.
高性能热塑性聚醚醚酮树脂基复合材料具有高韧性、耐疲劳、原材料可长期贮存、成型速度快、可重复加工和回收再利用等独特优势,在航空航天等工业领域应用广泛.粉末悬浮法通过将聚醚醚酮细粉配制成水基悬浮液实现对纤维充分浸渍,现已成为制备连续纤维增强热塑性预浸料的重要方式.本文重点开展反气相色谱法研究聚醚醚酮表面性质,并结合微观形貌、粒径分布等方面对比国内外聚醚醚酮树脂的差异.研究表明:进口聚醚醚酮树脂色散表面能(19.2 mJ/m2)明显低于同级别国产树脂(41.1 mJ/m2);极性探针分子吸附于聚醚醚酮表面的驱动力主要是酸碱作用力,表面总体表现为碱性.进口聚醚醚酮树脂相比于国产具有更高的极性,使其更容易分散在水中;而国产聚醚醚酮树脂微观形貌、表面性质则更加均匀.表面性质研究指导水基悬浮液配制,制备的连续纤维增强热塑性预浸料质量优异,孔隙率低于0.5％且纤维排布整齐,热塑性复合材料层压板层间剪切强度平均值达109 MPa,与传统热熔浸渍方法相比提升30％以上.
光催化CO2 还原技术既能实现节能减排,又能缓解能源短缺,符合当今绿色可持续发展的理念.本工作以静电纺丝技术制备的TiO2 纳米纤维为基质,结合水热还原法制备Bi@Bi4O5Br2/TiO2 复合纤维.利用XRD、SEM、HRTEM、XPS、UV-Vis和碳吸附等方法对其微观结构、形貌和光学性能进行表征.结果表明:TiO2 纳米纤维经Bi4O5Br2 复合后,光谱响应范围拓展到可见光区,光生电子还原能力增强,可以将CO2 还原成CH4 和CO;金属Bi的富集不仅能提高催化剂对酸性CO2 分子的吸附能力,增强CO2 转化效率,而且能改变光催化反应路径,并有醇类物质(CH3OH)的生成.模拟太阳光照射 3 h,Bi@Bi4O5Br2/TiO2 光催化CO2 还原生成CH4、CO和CH3OH的速率分别达到 3.87、1.06和 0.32 µmol·h-1·g-1.本文为探索高效二氧化碳光还原催化剂提供了新的机会.
核工业循环链中产生的大量含铀废水会对人类健康及生态环境造成损害,因此高效处理含铀废水是保障核工业可持续发展及人类生态安全的重要一环.以氧化石墨烯为前驱体自组装合成了聚乙烯亚胺(PEI)功能化的复合气凝胶(MGO/PEI),并用于去除水溶液中的U(Ⅵ).通过探究不同PEI投放量、稳定性、pH值、时间、U(Ⅵ)浓度及温度对U(VI)的去除影响.结果表明:在298 K、pH=6时,最大吸附量为1 027.01 mg·g-1,符合准二级动力学模型和Langmuir等温吸附模型.热力学常数表明MGO/PEI对U(Ⅵ)的吸附是一个自发吸热的过程.XPS分析表明去除机制主要是由于氨基及含氧官能团与U(VI)的表面络合.
钛/铝层状复合板兼具了钛合金高强耐腐蚀和铝合金轻质、价格低廉的多重优势,在航空航天、汽车制造、水下装备等领域具有广泛的潜在应用前景.为探究Ti/Al层状复合构件的连接行为,采用真空电子束焊(EBW)对Ti/Al层状复合板进行焊接,对焊接接头的微观组织、界面行为及力学性能进行了研究.研究结果表明:相比于单面焊,先Al后Ti双面焊可以有效提高Ti/Al层状复合板焊接接头的力学性能,焊接接头界面处无明显缺陷,在焊接接头Ti/Al界面处存在明显的金属间化合物(IMCs)层,化合物的形成顺序分别为TiAl3、TiAl、TiAl2.其中,TiAl2 是TiAl作为中间物经过一系列反应的产物.在保持Al层电子束流为43 mA不变条件下,随着Ti层焊接电子束流的增大,焊接接头的抗拉强度和延伸率均呈现先增大后减小的趋势,抗拉强度和延伸率最高可达 304.6 MPa和 10.4%,达到了母材强度的 57%,焊接接头的断裂机制主要为在IMCs位置产生的脆性断裂.
作为高效析氧反应(OER)贵金属基电催化剂的潜在替代品,储量丰富、成本低廉的过渡金属基电催化剂已经受到广泛研究,但仍存在活性低和导电性较差的问题.本文设计了一种利用Co-MOF(ZIF-67)为前驱体,通过吸附氯化钨(WCl6)后进一步的高温热解制备了富含氧空位的以氮掺杂碳(NC)为基底的CoWO4(CoWO4/NC)催化剂,对催化剂的投料比及煅烧温度进行了探索,测试了在碱性介质中的OER性能.测试结果表明:投料比为 1∶1且煅烧温度为 550℃时所制备的催化剂表现出较低的过电位(电流密度 10 mA·cm-2 对应的过电位为 346 mV)、较低的塔菲尔斜率(65 mV·dec-1)及较高的导电性,采用计时电位法测试了在碱性条件下的稳定性,在 22 h内性能没有明显衰减.该工作对过渡金属基催化剂的研究提供了新思路,对之后催化剂的设计具有一定指导意义.
柔性触觉传感器在电子皮肤、智能机器人、可穿戴电子设备和医疗健康等方面具有广阔的应用潜力.针对压阻型柔性触觉传感器灵敏度低和响应/恢复性能差等问题,提出一种近场电流体动力学直写方法制备基于醋酸纤维素(CA)/MXene多层纳米片复合纤维薄膜的柔性触觉传感器,以具有多孔结构的CA纤维作为桥联剂,将MXene纳米片组装成连续的具有孔隙结构的三维(3D)导电网络.与传统的柔性触觉传感器制备方法相比,该方法通过高压静电场作用有效提高CA/MXene复合纤维薄膜的电学性能,从而提高了柔性触觉传感器的传感性能.测试结果表明:柔性触觉传感器触觉压力感知范围为 9 Pa～10.2 kPa,在 9 Pa～5.6 kPa压力范围内,该传感器的灵敏度为 17.36 kPa-1,并且具有快速的响应/恢复性能(60.31/74.35 ms).实验结果表明该柔性触觉传感器能够识别手指的运动状态、呼吸状态和脉搏等信号,在人体运动检测和生理信号监测等方面具有广阔的应用前景.
