Highly thermal conductive graphene/carbon nanotubes films with controllable thickness as thermal management materials

As electronic devices continue to be integrated and miniaturized, the increased system power density leads to a continued increase in operating temperature, ultimately leading to degradation of stability and performance. Therefore, the development of thermal management materials with superior thermal conductivity is urgently needed. Herein, full-carbon graphitized graphene/carbon nanotubes (CNTs) (gGC) films with controlled thickness were fabricated through compositing followed by compaction. The appropriate amount of CNTs doping enlarges the crystallinity and improves the stacking order of the composite film during the structural evolution process. Ultimately, the thermal synergy between CNTs and graphene sheets accelerates the propagation of phonons and endows the free-standing gGC film with good performance. The flexible gGC film shows an in-plane thermal conductivity of 1280.3 W/mK, an electrical conductivity of 6559 S/cm, and the foldability of 10,000 times at a thickness of 30 μm. Moreover, gGC films with controllable thicknesses were successfully prepared through a convenient “multilayer compaction” strategy, which allows thick gGC films to maintain a high level of thermal dissipation, while effectively mitigating the rapid decline in thermal conductivity of the films with increasing thickness. This work provides a general method for the realization of large-scale and convenient production of high-thermally conductive thick films.     

Effect of the thicknesses of the Al2SiO5 ion conductor on the opto-electrical properties for all-solid electrochromic devices

In this study, an all-solid-state electrochromic device (ECD) with the structure of ITO/WO₃/Al₂SiO₅/NiO_x/ITO was prepared, and the effect of the Al₂SiO₅ solid electrolyte thicknesses on the opto-electrical performance was investigated. The microstructure and surface morphology were characterized using XRD, SEM and AFM, and the surface morphology and degree of surface looseness demonstrate a significant influence on the opto-electrical properties of ECDs. The charge transfer dynamics at the solid-solid interface were characterized using EIS to obtain an ionic conductivity of 4.637 × 10^-8 S/cm. CV, CA and UV–Visible spectra were employed to record the in situ electrochemical and optical properties. The results revealed that the highest optical modulation was 44.58%, the coloring and bleaching times were 14.8 s and 3.7 s, and the highest coloring efficiency was 98.17 cm²/C, which indicates that excellent opto-electrical properties were obtained. When the thickness increases, the degree of surface dense morphology transforms, and the loose morphology is more favorable for ion conductivity, which improves the opto-electrical properties. The results in this study provide insights into the understanding of Al³⁺-based all-solid-state ECDs, which promote the exploration of new types of Al³⁺ ionic conductors for all-solid-state ECDs.     

Design and fabrication of MoSe2/WO3 thin films for the construction of electrochromic devices on indium tin oxide based glass and flexible substrates

Electrochromic devices (ECDs) have the ability to block the heat generated by sunlight, making them ideal for use in smart windows. Herein, we report the fabrication of ECDs using MoSe₂/WO₃ (MSW) as the electrochromic material, for smart windows applications. A solvothermal method was used for the synthesis of MoSe₂, while WO₃ was synthesized using a sol-gel approach. Subsequently, MoSe₂/WO₃ (MSW) hybrids with different wt% of MoSe₂ (0.05 wt%, 0.2 wt%, 0.5 wt%) were synthesized using an ultra-sonication approach. The physicochemical features of these MSW hybrids herein termed as MSW 0.05, MSW 0.2 and MSW 0.5, were investigated using X-ray diffraction (XRD), X-ray photon electron spectroscopic (XPS), scanning electron microscope (SEM), and EDS techniques and compared with pristine MoSe₂ and WO₃. The ECDs synthesized using MSW 0.05 showed increased coloration efficiency (62 cm^2 C-1) with an applied potential range of 0 to −1.5 V. Subsequently, the ECDs based on indium tin oxide (ITO) and MSW 0.05 demonstrated excellent electrochromic performance and stability for 10,000 cycles. The enhanced electrochromic performance of the MSW-based ECDs may be attributed to the conductive nature as well as the synergistic effects between MoSe₂ and WO₃ when compared to the WO₃-based ECDs. The synthesized MSW also showed promise as an electrochromic material in flexible ECDs for smart windows applications.     

水热法制备石墨烯及对抗坏血酸电催化性能的研究

以氧化石墨烯为前驱液,采用水热技术在碱性环境下合成出水溶性较好的石墨烯。采用扫描电子显微镜技术（SEM）和X射线粉末衍射（XRD）对石墨烯的结构形貌做了表征。采用循环伏安法等电化学测试技术考察了石墨烯电极对抗坏血酸的电催化性能。实验结果表明,抗坏血酸在该石墨烯电极上的电化学活性显著提高。在pH=6.99条件下,峰电流响应最大。在优化条件下,抗坏血酸的响应电流和其响应浓度（1×10^-4~1×10^-3 mol/L）呈较好的线性关系,线性回归方程为I（A）=14 927.87c（mmol/L）+41.19,线性相关系数R²=0.998 9。该检测方法用于维生素C药片的实际测定,与标准测定方法相比,具有较高的准确度。     

钛酸锂/石墨烯复合负极材料的制备及电化学性能

以Li₂CO₃、锐钛矿TiO₂和石墨烯为原料，采用固相球磨及喷雾干燥相结合的方法制备钛酸锂和钛酸锂/石墨烯复合负极材料。用X射线衍射（XRD）、拉曼光谱、扫描电子显微镜（SEM）表征了样品的晶体结构及形貌。通过恒流充放电测试样品的电化学性能，考察不同石墨烯添加量对钛酸锂材料电化学性能的影响。当石墨烯添加量质量分数为1%时，钛酸锂/石墨烯复合负极材料（LTO-G-2）具有优异的倍率性能及循环稳定性。在0.2C、0.5C、1C、3C、5C和10C倍率下的充电比容量为172.9mA·h/g、165.7mA·h/g、163.5mA·h/g、157.4mA·h/g、154.0mA·h/g和143.5mA·h/g。5C倍率下经历200次循环，容量保持率为94.8%。循环伏安测试(CV)表明LTO-G-2样品的极化程度是最小的。交流阻抗测试（EIS）结果显示LTO-G-2的电荷转移阻抗（69.6Ω）小于纯的钛酸锂的电荷转移阻抗（140.5Ω）。