Key points of this article:
Prepare porous carbon nanosheets rich in intrinsic defects by pyrolysis directly in a sealed tube with potassium citrate.
The internal pressure generated in the sealed tube regulates the formation of inherent defects.
Porous carbon nanosheets provide high performance for supercapacitors and microwave absorption.
This work opens up new prospects for constructing advanced carbon materials with high density inherent defects.
Brief introduction of results
Rationally introducing inherent defects into porous carbon skeletons is an urgent need to expand the range of carbon material utilization, but it remains a challenge. In this paper, the team of Professor Li Yongfeng of China University of Petroleum (Beijing) published a paper in carbon journal titled "Intrinsic defect-rich porous carbon nanosheets synthesized from potassium citrate toward advanced supercapacitors and microwave absorption". The study proposes a simple but effective strategy to fabricate porous carbon nanosheets rich in intrinsic defects in sealed tubes (S-PCNs) using potassium citrate as the sole raw material.
The internal pressure inside the sealing tube leads to the formation of intrinsic defects, the density of which can be adjusted by the volume of the sealing tube. The obtained S-PCN gives a well-organized pore structure with uniformly distributed inherent defects. Benefit from redistributed surface charge, enhanced wettability and electrochemical surface area at an ultra-high power density of 50 kW kg-1. In addition, high density of inherent defects also brings strong polarization losses, balanced impedance matching. Therefore, even with an ultra-low packing load of 5 wt%, the optimal S-PCN as an electromagnetic wave absorber exhibits a maximum reflection loss of up to -58.2 dB, which means that almost all incident microwaves can be effectively consumed.
Illustrated reading
Figure 1. (a) Schematic of S-PCN synthesis and its dual application.
Figure 2. (a) SEM images of K 2 CO3 @O-HCC, (b, c) O-HCC, (d) K 2 CO 3 @S-PCN-3 and (e, f) S-PCN-3;
Figure 3. (a) Raman spectroscopy, (b) C1s spectroscopy, (c) EPR spectroscopy, (d) dynamic water contact angle measurement, (e) nitrogen adsorption-desorption isotherms, and (f) O-HCC and S-PCNs, inset (f) enlargement of pore partitions.
Figure 4. Electrochemical properties of the sample in a three-electrode system.
Figure 5. Electrochemical properties of SC.
Figure 6. (a) Reflection loss curves for O-HCC, (b) S-PCN-1, (c) S-PCN-2, and (d) S-PCN-3. (e) The tangent of the dielectric loss angle and (f) the modulus of the O-HCC and S-PCN Z in -1. (g) Comparison of S-PCN-3 MA performance with recently reported absorbents
brief summary
In summary, porous carbon nanosheets rich in intrinsic defects were successfully prepared by pyrolysis directly in a sealed tube. This work could provide new insights into the production of porous carbon materials rich in intrinsic defects.
Literature: https://doi.org/10.1016/j.carbon.2021.06.072