Nitrogen and oxygen co-doped micro-foam like mesoporous carbons are prepared from gelatin, an abundant hydrolyzed product of animal collagen with high carbon content and fruitful heteroatoms. Benefiting from the swelled structure of gelatin after pre‑carbonization at 300 °C, the following moderate chemical activation with KOH results in highly mesoporous carbons with specific surface area over 3000 m 2 g −1 and total pore volume larger than 1.96 cm 3 g −1 while preserving the micro-foam structure. As cathode materials of zinc ion capacitors (ZICs), the carbon micro-foams display very encouraging energy storage performance in both organic and aqueous electrolytes. A high energy density of 90 Wh kg −1 is obtained at a power density of 445 W kg −1 in 1 M Zn(CF 3 SO 3 ) 2 /DMF ( N , N -dimethylformamide) electrolyte, whereas in 1 M ZnSO 4 aqueous electrolyte the ZIC exhibits much better rate capability (54 Wh kg −1 at 14650 W kg −1 ) possibly due to the better wettability and higher ionic conductivity. These excellent electrochemical properties suggest that the N and O co-doped mesoporous carbon micro-foams derived from gelatin can be potential cathode materials of high-performance Zn-ion capacitors.
Controllable ice crystallization allows casting of isotropic or anisotropic porous aerogels to tailor versatile electromagnetic wave (EMW) absorbers. In this paper, a multivariate assembly-assisted bidirectional differ-speed freezing technique is developed to prepare the sandwiched nitrogen-doped carbon micro-foam/MXene/cellulose nanofiber aerogel (NCMF/MXene/CNF Aerogel, NCMCA). The NCMF, MXene, and CNF are assembled by alternating “foam-flake-fiber” through attractive interactions, and then undergo directional alignment under bi-directional cross-squeezing of ice crystals, forming a multi-stage anisotropic structure containing integrated periodic grid-like surface and honeycomb-like channels. The high porosity results in ultra-light density (6.2 mg cm −3 ) and thermal insulation (Δ T max = 140 °C). Silane deposition gives NCMCA a large water contact angle (≈133.6°) for anti-icing. Multi-component filling and compressive strain synergistically regulate electron transport and charge polarization for photothermal conversion, piezoresistive sensing, and microwave absorption. In particular, compression-driven dielectric coupling facilitates dynamic modulation of EMW absorption. In addition, NCMCA is capable of efficiently absorbing EMW under far-field conditions, thereby minimizing the radar scattering cross section. This work provides a novel structural design route for composite aerogels to achieve versatility, as well as new insights into the microstructural regulation mechanism of EMW absorption.
危险品化学品经营许可证（带存储）