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Precise control of versatile microstructure and properties of graphene aerogel via freezing manipulation.
Nanoscale ( IF 5.8 ) Pub Date : 2020-01-09 , DOI: 10.1039/c9nr07861d Xiangyu Zhu 1 , Chao Yang 2 , Pingwei Wu 3 , Zhenqian Ma 2 , Yuanyuan Shang 2 , Guangzhu Bai 2 , Xiaoyan Liu 2 , Guo Chang 2 , Ning Li 2 , Jingjie Dai 4 , Xitao Wang 2 , Hailong Zhang 2
Nanoscale ( IF 5.8 ) Pub Date : 2020-01-09 , DOI: 10.1039/c9nr07861d Xiangyu Zhu 1 , Chao Yang 2 , Pingwei Wu 3 , Zhenqian Ma 2 , Yuanyuan Shang 2 , Guangzhu Bai 2 , Xiaoyan Liu 2 , Guo Chang 2 , Ning Li 2 , Jingjie Dai 4 , Xitao Wang 2 , Hailong Zhang 2
Affiliation
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A deep understanding of the shaping technique is urgently required to precisely tailor the pore structure of a graphene aerogel (GA) in order to fit versatile application backgrounds. In the present study, the microstructure and properties of GA were regulated by freeze-casting using an ice crystal template frozen from -10 °C to -196 °C. The phase field simulation method was applied to probe the microstructural evolution of the graphene-H2O system during freezing. Both the experimental and simulation results suggested that the undercooling degree was fundamental to the nucleation and growth of ice crystals and dominated the derived morphology of GA. The pore size of GA was largely regulated from 240 to 6 μm via decreasing the freezing temperature from -10 °C to -196 °C but with a constant density of 8.3 mg cm-3. Rapid freeze casting endowed GA with a refined pore structure and therefore better thermal, electrical, and compressive properties, whereas the GA frozen slowly had superior absorption properties owing to the continuous and tube-like graphene lamellae. The GA frozen at -196 °C exhibited the highest Young's modulus of 327 kPa with similar densities to those reported in the literature. These findings demonstrate the diverse potential applications of GA with regulated pore morphologies and also contribute to cryogenic-induced phase separation methods.
中文翻译：
通过冷冻操作精确控制石墨烯气凝胶的通用微观结构和性能。
迫切需要对成型技术有深入的了解，以精确地定制石墨烯气凝胶（GA）的孔结构，以适应各种应用背景。在本研究中，通过使用从-10°C到-196°C冷冻的冰晶模板进行冷冻铸造来调节GA的微观结构和性能。应用相场模拟方法研究了石墨烯-H2O系统在冻结过程中的微观结构演变。实验和模拟结果均表明，过冷度是冰晶成核和生长的基础，并主导了GA的衍生形态。通过将冷冻温度从-10°C降低到-196°C，GA的孔径在240至6μm范围内得到了很大的调节，但恒定密度为8.3 mg cm-3。快速冷冻浇铸赋予了GA细化的孔结构，因此具有更好的热，电和压缩性能，而缓慢冻结的GA由于具有连续且呈管状的石墨烯薄片而具有优异的吸收性能。在-196°C下冷冻的GA表现出最高的杨氏模量327 kPa，其密度与文献报道的密度相似。这些发现证明了具有受控的孔形态的GA的各种潜在应用，并且还有助于低温诱导的相分离方法。s模量为327 kPa，密度与文献报道的相似。这些发现证明了具有受控孔形态的GA的各种潜在应用，并且还有助于低温诱导的相分离方法。s模量为327 kPa，密度与文献报道的相似。这些发现证明了具有受控孔形态的GA的各种潜在应用，并且还有助于低温诱导的相分离方法。
更新日期：2020-02-27
中文翻译：
通过冷冻操作精确控制石墨烯气凝胶的通用微观结构和性能。
迫切需要对成型技术有深入的了解，以精确地定制石墨烯气凝胶（GA）的孔结构，以适应各种应用背景。在本研究中，通过使用从-10°C到-196°C冷冻的冰晶模板进行冷冻铸造来调节GA的微观结构和性能。应用相场模拟方法研究了石墨烯-H2O系统在冻结过程中的微观结构演变。实验和模拟结果均表明，过冷度是冰晶成核和生长的基础，并主导了GA的衍生形态。通过将冷冻温度从-10°C降低到-196°C，GA的孔径在240至6μm范围内得到了很大的调节，但恒定密度为8.3 mg cm-3。快速冷冻浇铸赋予了GA细化的孔结构，因此具有更好的热，电和压缩性能，而缓慢冻结的GA由于具有连续且呈管状的石墨烯薄片而具有优异的吸收性能。在-196°C下冷冻的GA表现出最高的杨氏模量327 kPa，其密度与文献报道的密度相似。这些发现证明了具有受控的孔形态的GA的各种潜在应用，并且还有助于低温诱导的相分离方法。s模量为327 kPa，密度与文献报道的相似。这些发现证明了具有受控孔形态的GA的各种潜在应用，并且还有助于低温诱导的相分离方法。s模量为327 kPa，密度与文献报道的相似。这些发现证明了具有受控孔形态的GA的各种潜在应用，并且还有助于低温诱导的相分离方法。
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