| In this era of nanoscience,the control synthesis of nanomaterials with specific structures/properties is in hot pursuit.In recent years,with the development of electron microscopy,researchers have been able to observe the details of various organisms at micro-nano scale;and as a result,the related bionics research has emerged and a range of high-performance bionic functional materials/models have been synthesized/established.Among them,hierarchical porous materials with multi-scale pore structures and small densities possess promising applications in gas/oil-water separation,wastewater treatment,anti-/deicing technique,seawater desalination,catalysis,sensors,water vapor collection,etc.In addition,carbon materials with the structural characteristics such as wide working temperature range,good long-term stability,corrosion resistance and non-toxic,are ideal candidates for the above applications.Therefore,the application-driven construction of high-performance hierarchical porous carbon-based composites is one of the key research directions of emerging nano functional materials.In Chapter 2,in order to address the problems of the current prevailing anti-/deicing coatings which have poor anti-icing performance at low temperature and high humidity,high energy consumption,narrow application range and are not easy to repair,materials such as multi-walled carbon nanotubes（MWCNTs）and layered alkali zinc acetate（LBZA）microspheres are self-assembled into a bionic micro-nano hierarchical porous superhydrophobic overlayer that can be used for all-weather anti-/deicing.Specifically,LBZA microspheres with micro-nano porous structure were synthesized by a hydrothermal method,which was then integrated with ball-milled MWCNTs and polydopamine（PDA）to establish a hierarchical porous structure.The anti-icing performance on the surfaces of different hydrophobic structures was investigated by in situ environmental scanning electron microscopy（ESEM）from the microscopic scale,and the anti-icing mechanism of superhydrophobic characteristic of composited hierarchical porous overlayer was thus extracted.Furthermore,the excellent photothermal and electrothermal properties of the overlayer can also be used for active deicing.As a result,the MWCNTs-LBZA-PDA superhydrophobic overlayer exhibited an average anti-icing time of up to 112.5 min at-10 oC and a relative humidity of 75±5%,with surface equilibrium temperatures of up to 74 oC and 105 oC under the excitation of one solar intensity and 30 V DC voltage,respectively.In Chapter 3,in order to address the problems of existing piezoresistive sensors with general mechanical properties,small detectable pressure range and large output signal fluctuations under long cycle tests,aramid nanofibers/reduced graphene oxide composite aerogel with hierarchical porosity was prepared by using an ice-templated method,and its structural characteristics such as lightweight high-elastic and favorable three-dimensional conductive network enable the aerogel great potentials as piezoresistive sensors.Aramid nanofibers（ANFs）was prepared by chemical exfoliation,and a stable composite aerogel with hierarchical porosity was constructed by employing the hydrogen bonds between graphene oxide（GO）flakes and ANFs.The effects of different component ratios on the structure of the composite aerogel and the effects of different freezing methods on the mechanical and piezoresistive sensing properties of the composite aerogel were investigated.It was found that when the ratio of ANFs to GO was 3:2,the prepared composite aerogel exhibited the best porous structure.The density of composite aerogel was as low as 10.326 mg cm-3,the compressive strength at 90%strain was as high as 75 k Pa,and the height remaining rate after 1000 times compression at 50%strain was 97.33%.The corresponding piezoresistive sensor exhibited good response stability under 2.5%-90%strain and1000 long compression cycles.Moreover,when the aerogel was used as a piezoresistive sensor,it can effectively detect both small deformations including finger bending,throat vibrations and large deformations as sittings and standings.In conclusion,hierarchical porous carbon-based composited materials were prepared by different methods,and their applications as high-performance anti-/deicing overlayers and lightweight high-elastic piezoresistive sensors were investigated,which may shed light on the design and engineering of future hierarchical porous carbon-based composited materials. |
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