1成果简介
　　相变材料（PCM）在储存和释放热能方面具有巨大潜力，但其光吸收性差、热导率低、形状稳定性弱等缺点严重制约了太阳能的吸收、转化和利用。本文，天津工业大学Na Han等研究人员在《Carbon》期刊发表名为“Cyclized polyacrylonitrile@carbon nanotubes reinforced graphene aerogel phase change composites for efficient solar-thermal-electric energy conversion”的论文，研究受关节结构的启发，制备了环化聚丙烯腈@碳纳米管（CPAN@CNT）/石墨烯混合气凝胶（CPAN@CNT/GA）。CPAN@CNT的引入增强了气凝胶的机械性能和导热性，建立了连续稳定的传热途径，确保了下一步PCM的稳定封装。
　　在50%的压缩应变下，CPAN@CNT/GA 的压缩强度增加到7.8kPa，显示出稳定的压缩回弹性。石蜡（PW）作为 PCM，通过真空浸渍与 CPAN@CNT/GA 集成，制备出 PW/CPAN@CNT/GA 形状稳定相变材料（SSPCM）。PW/CPAN@CNT/GA 具有高潜热（190.1 J g-1）、高热导率（0.764W m-1 K-1）和优异的光热转换效率（93.7%）。PW/CPAN@CNT/GA 还展示了其先进的太阳能-热能-电能转换潜力。在模拟太阳光（2 kW m-2)）下，输出电压足以为额定电压为 2V 的电子设备供电，即使在无光的情况下也能提供额外的工作时间。这项研究提出了一种可行而有效的方法，用于制造具有高潜热保留的 SSPCM，从而实现高效的太阳能-热能-电能转换。
　　2图文导读 

　　图1. Schematic illustration of the fabricating procedure of PW/CPAN@CNT/GA.

　　图2. a) FTIR spectra of CNTs, PAN@CNT, CPAN@CNT, GO, rGA, PCGA and CPAN@CNT/GA. b, c) C 1s XPS spectra, d) Raman spectra, e) XRD patterns of GO, rGA, PCGA and CPAN@CNT/GA. f) TGA curves of CNTs, PAN@CNT, PAN, GO, rGA, PCGA and CPAN@CNT/GA.

　　图 3. a-h) SEM images of rGA, CPAN@CNT/GA-1, 2, 3, 4, 5, 6 and 7. i) SEM images of PCGA. j) SEM images of CPAN@CNT/GA. k) EDS mapping images of CPAN@CNT/GA. l-n) TEM images of CPAN@CNT/GA with various magnification.

　　图4. a) Compressive stress of rGA, CGA, PCGA, CPAN@CNT/GA, PGA and CPGA at 20% and 50% strain. b) Compressive stress of CPAN@CNT/GA with different PAN@CNT content. c) Stress-strain curves of CPAN@CNT/GA with 10 cycles. d) Comparison of compression results with other studies. e) Time-temperature curves of rGA and CPAN@CNT/GA heating on 100°C and 200°C hot plates. f) Thermal conductivity of rGA, PCGA, CPAN@CNT/GA, PW/CPAN@CNT/GA and PW. g) The schematic of the articular structure.

　　图5. a) FTIR spectra of PW and PW/CPAN@CNT/GA. b) Heating and c) cooling DSC curves of PW, CPAN@CNT/GA and PW/CPAN@CNT/GA. d) Enthalpy and phase change temperatures of PW and PW/CPAN@CNT/GA. e, f) FTIR spectra and DSC curves of PW/CPAN@CNT/GA for 100 cycles. g) Infrared images of PW/CPAN@CNT/GA on a 100 °C hot plate. h) Time-temperature curves of CPAN@CNT/GA, PW/CPAN@CNT/GA and DPGA on a 100 °C hot plate.

　　图6. a) Schematic diagram of PW/CPAN@CNT/GA in the field of solar-thermal energy conversion. b) Schematic diagram of simulated sunlight exposure. c) Ultraviolet-visible-near-infrared absorption spectra of PW and PW/CPAN@CNT/GA. d) Time-temperature curves of CPAN@CNT/GA, PW and PW/CPAN@CNT/GA under 1 kW m-2 irradiation.

　　图7. a) Schematic drawing of STEG system. b) Output voltages of the blank, PW and PW/CPAN@CNT/GA-covered thermoelectrics when the heatsink is in the air. c) Output voltages and d) currents of PW/CPAN@CNT/GA-covered thermoelectrics when the heatsink is in the air. e) Steady output electricity of PW/CPAN@CNT/GA. f) STEG uses proof-of-concept experiments to sustain the operation of electronic devices. g) Digital pictures of power generation devices. h) Digital pictures of electrical devices at work.
　　3小结
　　总之，受关节结构的启发，我们报告了一种增强气凝胶结构稳定性的 CPAN@CNT/GA 制备策略。我们在 CNT 上原位生长了 PAN，将其作为构筑基块，并通过水热还原 LGO 合成了混合气凝胶。热处理后，PAN发生环化，在气凝胶中形成无机-有机-无机π-π相互作用体系，从而显著提高了CPAN@CNT/GA的结构稳定性和导热性，并确保了PCM的稳定封装。所制备的 CPAN@CNT/GA 具有优异的压缩回弹性，在 50%应变下的最大应力为 7.8 kPa。CPAN@CNT/GA 被用作封装 PW 的框架，从而产生了一种具有优异导热性、低负载和高潜热保留的 SSPCMs。此外，PW/CPAN@CNT/GA 还具有优异的光热转换特性，在太阳能-热能-电能转换应用中性能显著。采用 PW/CPAN@CNT/GA 的太阳能热电发生器在 3 kW m-2 的光照射下可获得 541.9 mV 的高输出电压和 92.2 mA 的电流。同时，小型热电发生器为计算器和 LED 供电，即使在黑暗中也能持续产生电信号一段时间。这项工作证明了基于光热效应的 SSPCM 在高效太阳能转换、储存和利用方面的巨大潜力，有助于解决能源短缺和太阳能供需失衡问题。预计太阳能驱动的热增强型 SSPCM 将为 STEG 的发展展现巨大潜力。
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