At the Chinese Academy of Sciences' (CAS) Hefei Institutes of Physical Science (HFIPS), Prof. Zhenyang Wang’s research group recently created macroscopic thick three-dimensional (3D) porous graphene films.
(a) A schematic diagram of the process of e-beam bombardment to form graphene on polyimide. (b) SEM image of EIG. (c-d) Low and high magnification cross-section SEM images of EIG. (e-f) TEM and HRTEM images of EIG. (g) Raman spectrum (above) and XRD spectra (below) of EIG and polyimide film. (h) The CV curves at different scan rates of EIG electrode. (i) The GCD diagrams at different current densities of EIG electrode. (j) Photothermal performance of EIG materials at −40 °C. Image Credit: Hefei Institutes of Physical Science (HFIPS).
The researchers directly introduced polyimide precursor into a 3D porous graphene crystal layer with a thickness of up to 0.66 mm using a high-energy electron beam as the energy source, taking advantage of the e-high beam’s kinetic energy and low reflection properties. The findings of the study were published in the journal Carbon.
Due to its multiple remarkable chemical and physical properties, graphene has be a new strategic material. The integration of a three-dimensional (3D) porous graphene network can prevent graphene sheets from becoming restacked and enables simple ion access and diffusion. The manufacture of macroscopic thick 3D porous graphene films in a cost-effective manner, however, remains difficult.
The high instantaneous energy of a laser can cause direct carbonization of the carbon-containing matrix, resulting in high-quality crystalline graphene. However, because the laser’s penetration depth into the carbon-containing matrix is so shallow, the generated graphene film is too thin, limiting its use in practical devices.
As a result, finding a more efficient energy source is a critical issue that must be addressed quickly if high-energy beam-induced graphene is to be used in industries.
The researchers used a new energy source, a high-intensity e-beam, in this study to achieve an effective synthesis of macroscopic thick 3D porous graphene crystal sheets on the polyimide precursor.
When compared to lasers, high-energy e-beams have a number of advantages, such as high kinetic energy, zero reflection, simple focus control and injection effect, which makes the e-beam a potentially better energy source than lasers for quickly carbonizing polyimide precursors to generate graphene.
Hydrogen, oxygen and other components in polyimide can quickly escape as gas, leading to a dense 3D pore structure in graphene.
The thickness of an e-beam-induced graphene (EIG) layer can be as high as 0.66 mm, and the synthesis rate can be as high as 84 cm2/minute, which is substantially faster than a laser. EIG has also been effectively applied to supercapacitor electrodes, demonstrating good electrochemical storage capacity.
EIG can be used in solar photothermal anti-icing and deicing because of its excellent photothermal performance. Temperatures as low as −40 °C have been recorded.
This study was financially supported by the National Key Research and Development Project of China, the National Natural Science Foundation of China, and the Anhui Key Research and Development Program.
Journal Reference:
Han, S., et al. (2021) E-beam direct synthesis of macroscopic thick 3D porous graphene films. Carbon. doi.org/10.1016/j.carbon.2021.06.035.