Jingtao Su's research while affiliated with GuangDong University of Technology and other places

Advanced multifunctional composite materials have been a significant force in the advancement of efficient solar-thermal energy conversion and storage, which is critical to address current energy shortage problems. In this study, novel phase change material (PCM) composite fiber films, composed of Py-CH (one novel pyrene-based aggregation-induced emission luminogen (AIEgen))/polyvinyl pyrrolidone (PVP)/polyethylene glycol (PEG), have been produced by electrospinning technology with PEG as the phase change material. The combination of AIE and twist intermolecular charge transfer (TICT) characteristics of Py-CH together with the water absorption performance of PVP afforded a temperature-dependent fluorescence change. On increasing the temperature from 30 to 160 °C, the APP (pyrene-based AIEgen/PVP/PEG) composites exhibit a blue-shifted emission with a color changed from green-yellow to cyan, from cyan to blue, and finally, to purple. Furthermore, the entanglement of the macromolecular chains and distinctive porous structure between PVP and PEG played a significant role in preventing the leakage and transfer issues of PEG. Therefore, the composite fiber films with a PEG content of 60% exhibited latent heat in the range of 79~89 J/g and were extremely stable for up to 100 heating-cooling cycles. As a result, the application of these APP composites could be further promoted to solar energy conversation and storage, high-temperature warning, and anti-counterfeiting applications. Hence, composite materials containing the pyrene-based AIEgen and phase change materials have opened up new avenues for the possible application of such materials in thermal energy storage. Graphical Abstract

Polyimide (PI), as an advanced polymer material, possesses the intrinsic merits of excellent resistance to extreme temperatures, good dielectric properties, flame resistance, strong processibility, biocompatibility, and flexibility. The outstanding performances of flexible PI have led to a wide range of applications in aerospace, medical, intelligent electronic devices, energy storage devices, and more. Notably, due to the swift progress of various flexible and soft devices, flexible PI has become ubiquitous in the form of thin films, fibers, and foam and gradually plays an indispensable role in all sorts of those devices. This review mainly focuses on the current advances in the usage of flexible PI for barrier, sensor, and functional purposes. Firstly, the key features of various methods for synthesizing and processing PI, as well as the relationship with their respective applications, are summarized. Secondly, to give readers a comprehensive view of the various applications of flexible PI materials, the applications are broken down into three categories: flexible barrier applications, flexible sensing applications, and flexible function applications, and the current research of each application is introduced in detail. Finally, a summary of the challenges and possible solutions in some flexible applications is present.

Liquid-solid organic phase change materials (PCMs) exist shortcomings of leakage, poor solar-to-thermal conversion efficiency, and flammability, which restrict the application scope of solar-thermal energy storage. To meet these problems, PCMs ([email protected]) with excellent thermal energy storage, solar-to-thermal conversion, and flame retardancy were fabricated in this study. The polyimide (PI)/sodium lignosulfonate-zirconium phosphate (SL-ZrP) hybrid-aerogels (ZrP-PI) were prepared by freeze-drying and thermal imidization. ZrP-PI aerogels composited with polyethylene glycol (PEG) via vacuum impregnation to fabricate the composite PCMs (CPCMs, [email protected]). The in-situ biochar generated from SL-ZrP increases both solar-to-thermal conversion and flame retardant of CPCMs. The final result demonstrates that [email protected] exhibits a superior adsorption ratio (95.5%) and outstanding latent heat (157.67 J/g), as well as about 13% flame retardant index decrease in heat release rate (HRR) and total heat release rate (THR). Furthermore, [email protected] shows great thermal stability and reliability after conducting a leakage experiment and thermal cycling test. These superior resultants indicate that [email protected] has a good potential for widespread and long-term use in solar thermal energy storage.

In recent years paraffin-based organic phase change materials have been widely employed in thermal-energy storage systems due to their relatively high latent thermal capacity. However, the risk of leaks, low thermal conductivity, and low light-to-thermal conversion capacity has, to date, limited their use in the storage of solar thermal energy. To address these issues, we have developed a novel bio-based shape-stable organic phase change composite (SSOPCC) by encapsulating paraffin C22 with the double-supporting component consisting of poly (styrene-b-ethylene-co-butylene-b-styrene) (SEBS) and expanded perlite (EP), and improving the thermal conductivity and increasing the sensitive light response rate by introducing boron nitride (BN) and a lignin biomass-derived carbon material carbonized lignin (CL). Our investigations show that, with the introduction of the BN sheets and biomass CL into the SSOPCCs, the thermal conductivity of the composites is improved (from 0.407 W/mK to 0.596 W/mK), and the light-to-thermal conversion ability is also considerably enhanced. The obtained SSOPCCs possess not only good thermal storage performance, such as high latent heat enthalpy (as large as 185.5 J/g) and high relative enthalpy efficiency (>95%) but also exhibit excellent thermal stability and reliability after multiple heating-cooling cycles. The findings of this study will both provide a promising way for fabricating new bio-based phase change composites for real solar energy storage and conversion applications and broaden the high-value utilization of lignin-based biomass.

The syngas generation from biomass/vapour pyrolysis wih molten copper slag is an innovative technology in chemical industry. Copper slag and rice straws are representative undervalued trashes as metallurgical and agricultural by-products. But the inappropriate handling of them, including direct burying or open burning, could severely aggregate environmental pollution. This present study investigated the biomass pyrolysis integrating waste heat from molten copper slags through carbon-loops extension. The mechanism of integrated looping gasification was identified, where the effects of the mass ratio of FeO/SiO2, minor elements contents of (Al2O3+CaO), operational temperature and pressure on target syngas yields were systematically explored through thermodynamic calculation and experimental results. Thermodynamics calculations confirmed that increased mass ratio of FeO/SiO2 (higher than 1.5) and minor elements contents showed obvious catalytic effect on syngas generations, promoted , accompanied with obvious reduction of air pollutants emission. Since FeO favoured solid biomass conversion into syngas, exergy efficiency of generated syngas increased as the mass ratio of FeO/SiO2 was enhanced. Non-isothermal experiments confirmed the incorporation of FS1-5 and FS5-1 obviously undermined the polluting gas yields, which were in overall agreement with thermodynamics results. Meanwhile, the solid ash waste could serve as raw materials for soil nutrients, and the generated syngas could be utilized for electricity generation, based on which an integrated and sustainable looping system would be proposed. Therefore, the favourable results could thus provide significant insights for deepened understanding of biomass gasification as well as the efficient utilization of rice straw and copper slag.