摘要 : High-performance porous polyimide (PI) monoliths, including PI aerogels, sponges, and foams, have become one of the hotspots in both researching and applications due to their superior properties such as high porosity, outstanding mechanical and thermal stability, low dielectric constant and thermal conductivity. Up to now, various fabricating methods and applicating situations for PI porous monolith materials have been reported. From the viewpoint of molecular chemistry, porous structure construction, as well as the functional modification, the property optimization and adjustment are feasible, endowing PI monoliths with promising potential for different practical applications ( e.g. sensors, low-k materials, thermal management, energy field and utilization, absorption and filtration, photonic utilization, etc.). In this review, the recent progress of porous PI monoliths was summarized in detail based on the fabrication methods, functional modifications, as well as multi-functional applications. Besides, the future perspectives of this field were also provided for reference. Apart from presenting an overview of progress made in the field of PI porous monoliths, this review could also be meaningful for those researching topics which have similarity within.

摘要 : As a convenient photothermal material, polydopamine (PDA) has been widely utilized in wood-based evaporators. However, the loading conditions of polydopamine on biomass bulk materials have not been systematically studied. In this paper, the suitable reaction conditions of polydopamine were studied with rattan as the substrate, and a reference for the improvement of the loading conditions was proposed. The polydopamine-loaded rattan-based evaporator (PDA-R) prepared on this basis exhibits excellent working stability due to the unique large-scale hierarchical porous structure of rattan. In addition to excellent salt resistance and cycle performance (evaporation rate decays by 5.1% after 30 cycles), the larger-aperture channel (200–450 μm) also brings better adaptability to salinity changes than polydopamine-loaded basswood-based evaporator (PDA-BW) (the attenuation coefficient of PDA-R is 6.2%, while the attenuation coefficient of PDA-BW is 16.3%). All of these indicate the broad prospects of polydopamine-loaded rattan-based evaporator as a multi-effect treatment scheme of brine.

摘要 : In this study, a nitrogen/oxygen co-doped carbon fiber cloth with a hierarchical porous structure was synthesized by one-step carbonization and in situ activation method and acted as binder-free electrode materials for supercapacitors. Cotton fiber cloth served as the carbon precursor, while molecular dispersed CaCl 2 ·6H 2 O and urea functioned as activator and N dopant, respectively. The influence of molar concentration of CaCl 2 ·6H 2 O and urea on the microstructure and capacitive performance of the resulting products were investigated. CaCl 2 ·6H 2 O has an expansion effect on pores, resulting in reduction of micropores. Hence, the specific surface area of the resulting porous carbon increased first and then decreased with the increase of CaCl 2 ·6H 2 O concentration. In addition, the erosion of NH 3 and CO 2 (produced by the decomposition of urea) at high temperature on the surface of the samples promoted the formation of porous structure. Urea plays the dual role of doping and activation agent. The morphology and structure analysis shown that the activated samples exhibited hierarchical pore structure, large specific surface area, and high heteroatom content. The optimal sample NAC-20 exhibited good capacitive performance, including high specific capacitance of 260.9 F g −1 at 0.1 A g −1 and good rate performance. Moreover, the symmetric supercapacitor exhibited a maximum energy density and power density of 16.2 Wh kg −1 and 19.0 kW kg −1, respectively, in 6 M KOH electrolyte. In this work, a green, low-cost molten salt activation method was proposed to synthesis biomass derived porous carbon materials for energy storage devices.

摘要 : Carbon aerogel is one of the ideal materials for supercapacitor because of its high specific surface area and high conductivity. Sodium carboxymethyl cellulose (CMC-Na) has attracted much attention owing to its water solubility. In this work, we have provided a simple and facile strategy by zinc nitrate hexahydrate (Zn(NO 3 ) 2 ·6H 2 O) as an activative agent and urea (CO(NH 2 ) 2 ) as a nitrogen source to achieve the N/O co-doped carbon aerogels. Just as bread expands during baking, the introduction of these agents makes the materials expand and fluffy. By changing the amount of Zn(NO 3 ) 2 ·6H 2 O and CO(NH 2 ) 2, the microstructure and element content can be controlled. When the mass ratio of CMC-Na, Zn(NO 3 ) 2 ·6H 2 O and CO(NH 2 ) 2 was 2:1:4, we obtained the highest specific capacitance in a three-electrode system (248 F g −1 at 0.1 A g −1 ). This value was more than three times higher than that of pure CMC-Na derived carbon materials. In the symmetrical supercapacitor, the maximum specific capacitance was 129 F g −1 at 0.1 A g −1 . It was assembled into a coin cell for long cycle stability test and the capacitance retention maintained 90 % at 30 A g −1 for 15, 000 cycles. Compared with the traditional method of carbonization followed by activation, this work exhibits a simpler strategy by one-step carbonization and activation and shows the prospect of CMC-Na as a precursor of the carbon electrode in the field of energy storage.

摘要 : The incorporation of graphene quantum dots (GQDs) with efficient charge carrier transport capability into a tin oxide (SnO2) solution and the utilization of their distinct mass properties for effective self-stratification are proposed as a method for enhancing the efficiency and stability of perovskite solar cells. By employing an antisolvent spin-coating technique, an SnO2 electron transport layer (ETL) with a gradient energy band structure is prepared. Devices based on this gradient energy band ETL exhibit an efficiency of 22.3%, whereas the efficiency of devices with a single SnO2 ETL, used as a reference, is only 19.8%. Moreover, for unencapsulated devices, an efficiency of 86% is retained after continuous testing for 1000 h at 40 °C by an AM 1.5 G lamp. Further investigation reveals that the introduction of GQDs not only forms a gradient energy band structure but also effectively passivates the defects in the SnO2 layer itself, thus ameliorating the issues of charge carrier separation and recombination during the transport process. This work presents an approach to SnO2 ETL design, not only applicable to perovskite solar cells but also offering inspiration for other optoelectronic devices.

摘要 : Solvatochromic fluorophores are one of the most investigated dyes because they exhibit multi-color luminescence properties as the polarity of the solvent changes. It remains a challenge to regulate solvatochromism with a large emission shift and maintain high fluorescence efficiency from apolar to polar solvents . Herein, we report a new type of solvatochromic fluorophore that exhibits both multicolor solvatochromism and stable high fluorescence efficiency in polar solvents . The unique solvatochromic properties of indoleninonaphthooxazole derivatives are realized by constructing a single carbon-bond-linked coplanar scaffold containing indolenine and naphthooxazole components with different substituents. We propose a possible mechanism to explain the unique solvatochromism. Excited USTS-3 and USTS-4 exhibit LE state in non-polar solvent and different HLCT states in polar solvents with both high luminescence efficiency. And the excitation of USTS-3 and USTS-4 is determined by aggregation states of molecular USTS-3 and USTS-4 under different concentrations, which exhibits different relaxations but share the same luminescence decay pathway. Benefitting from the unique luminescence properties of indoleninonaphthooxazole derivatives, they exhibit potential applications in solvent polarity detection, bioimaging, anticounterfeiting, electroluminescence, and lighting in different matrix. Our results also provide a new perspective on designing novel fluorophores based on indolenine and naphthoxazole moieties.

摘要 : The effective utilization of Lewis acid-base reactions plays a pivotal role in achieving high power conversion efficiency (PCE) in perovskite solar cells while ensuring exceptional stability. In this study, we introduce the Lewis acid-base reaction as a potent modification technique for enhancing the performance of the tin oxide (SnO 2 ) -based electron transport layer (ETL) in perovskite solar cells. Devices employing this modified ETL exhibit an impressive efficiency of 22.2%, surpassing the reference devices with a single SnO 2 ETL, which achieve only 19.5% efficiency. Moreover, these Lewis acid-base-modified ETLs demonstrate outstanding stability, retaining over 90% efficiency even after 1000 h of exposure under AM 1.5G lamp irradiation with negligible hysteresis effects. Further investigation reveals that the performance enhancement can be attributed to various mechanisms. The Lewis acid-base reaction not only mitigates inherent defects within the SnO 2 layer but also significantly improves the deposition of subsequent perovskite layers. Our research makes a substantial contribution to the advancement of perovskite solar cell technology, providing a promising avenue for more efficient and durable energy conversion devices.

摘要 : Cellulose derivatives are widely used as carbon precursors for porous carbon materials because of their high carbon contents and low cost. Herein, N/O co-doped porous carbon materials were synthesized from sodium carboxymethyl cellulose by one-step carbonization and activation with zinc nitrate hexahydrate, a lewis acid salt, as the chemical foaming agent and activation agent and urea as the nitrogen source. The nitrogen content and oxygen content of the optimized sample reached 7.6 at.% and 12.7 at.%, respectively, and the specific surface area reached 1318 m 2 g −1 . The doping of nitrogen element increased the specific capacitance by nearly two times. In a three-electrode system, the maximum specific capacitance reached 234 F g −1 at 0.1 A g −1 in 6 M KOH electrolyte. The maximum energy density of symmetric supercapacitor was 15.7 Wh kg −1 at the power density of 497.3 W kg −1 . The capacitance retention maintained 90.3 % after 10, 000 cycles at 20 A g −1 . This work provides a novel method for the preparation of porous carbon materials derived from sodium carboxymethyl cellulose and expands its application in energy storage devices.

摘要 : The thick electrode design with high packing density of active materials can increase the capacity in a limited space. However, the key challenge is still to develop a system with high space utilization and ensure electron/ion transport in thick electrode. This work proposes an interesting "rebar-concrete" structure, which successfully prepared wood/phenolic resin-derived thick electrode with high space utilization by in-situ polymerization of phenolic resin (concrete) in the wood (rebar) channel. The electrode exhibits an excellent three-dimensional interconnected hierarchical pore structure due to the uniform activation of in-situ anchored KOH particles. The mass loading (35 mg cm −2 ) and areal capacitance (11F cm −2 ) of the obtained composite electrode are increased to 446 % and 1257 % of the original balsa wood, respectively. The assembled symmetric supercapacitor (SSC) exhibits a high energy density of 0.63 mWh cm −2 (3.91 mWh cm −3 ) and an excellent cycle stability (95 % retention after 50 000 cycles), showing good practicability in lighting LEDs or driving a fan. This strategy achieves effective coupling of self-supporting skeleton and powder materials, providing more insights and possibilities for the preparation of high energy density thick electrodes.

摘要 : With the rapid development of the Internet of Things, nanogenerator as a green energy collection technology has attracted great attention in various fields. Specifically, the natural renewable nanocellulose as a raw material can significantly improve the environmental friendliness of the nanocellulose-based nanogenerators, which also makes the nanocellulose based nanogenerators expected to further develop in areas such as wearable devices and sensor networks. This paper mainly reports the application of nanocellulose in nanogenerator, focusing on the sensor. The types, sources and preparation methods of nanocellulose are briefly introduced. At the same time, the special structure of nanocellulose highlights the advantages of nanocellulose in nanogenerators. Then, the application of nanocellulose-based nanogenerators in sensors is introduced. Finally, the future development prospects and shortcomings of this nanogenerator are discussed.