Carbon materials derived from chitosan/cellulose cryogel-supported zeolite imidazole frameworks for potential supercapacitor application

Abstract

a b s t r a c tIn order to promote sustainable development, green and renewable clean energy technologies continue to be developed to meet the growing demand for energy, such as supercapacitor, fuel cells and lithiumion battery. It is urgent to develop appropriate nanomaterials for these energy technologies to reduce the volume of the device, improve the efficiency of energy conversion and enlarge the energy storage capacity. Here, chitosan/cellulose carbon cryogel (CCS/CCL) were designed and synthesized. Through the introduction of zeolite imidazole frameworks (ZIFs) into the chitosan/cellulose cryogels, the obtained materials showed a microstructure of ZIF-7 (a kind of ZIFs) coated chitosan/cellulose fibers (CS/CL). After carbonizing, the as-prepared carbonized ZIF-7@cellulose cryogel (NC@CCL, NC is carbonized ZIF-7) and carbonized ZIF-7@chitosan cryogel (NC@CCS) exhibited suitable microspore contents of 34.37% and 30%, respectively, and they both showed an internal resistance lower than 2 . Thereby, NC@CCL and NC@CCS exhibited a high specific capacitance of 150.4 F g −1 and 173.1 F g −1 , respectively, which were much higher than those of the original materials. This approach offers a facile method for improving the strength and electronic conductivity of carbon cryogel derived from nature polymers, and also efficiently inhibits the agglomeration of cryogel during carbonization in high temperature, which opens a novel avenue for the development of carbon cryogel materials for application in energy conversion systems.

Cobalt Nanoparticles and Atomic Sites in Nitrogen‐Doped Carbon Frameworks for Highly Sensitive Sensing of Hydrogen Peroxide

“…The calculated percentage of pores above 2 nm increases from 61.76% (Co‐N/C) to 72.73% (Co‐N/CNT), especially the pores between 2 and 4 nm ( Figure a), while the specific surface area of Co‐N/CNT reduces from 367 to 261 m 2 g −1 (Table S1, Supporting Information). The more mesopores and smaller SSA of Co‐N/CNT can be attributed to the sandwich‐like structure and growth of N/CNT arrays . In addition, X‐ray photoelectron spectroscopy (XPS) results reveal that compared with Co‐N/C, the contents of carbon (88.74%) and nitrogen (6.62%) elements of Co‐N/CNT increase significantly, while the contents of cobalt (from 5.82% to 1.44%) and oxygen (from 16.00% to 3.20%) decrease a lot (Figure S7a and Table S2, Supporting Information).…”

The Renewable and Sustainable Conversion of Chitin into a Chiral Nitrogen‐Doped Carbon‐Sheath Nanofiber for Enantioselective Adsorption

“…The C/O and C/N ratios were observed to increaseb yf actors of approximately 2.01 and 1.46, respectively,d uring HTC, compared to those of pristine chiralc hitin;t he surface carbonization efficiency was similar to that exhibited by chitosan during HTC, [16,44] which suggests that the hydrothermally treated chitin nanofibril has more carbonized sheath and less carbonized core because HTC has as omewhat lower carbonization efficiency for chitin than high-temperature dry carbonization. [49] Collectively,t he XPS results reaffirm the surface carbonization of chiral chitin by the HTC method. The N1ss pectrum of pristine chiral chitin exhibitsapeak at 400.2 eV,w hich is assigned to the acetamideN .T he N1ss pectrum showed three representative N-doped carbonp eaks after hydrothermalt reatment, at 402.1, 400.9,a nd 398.2 eV,w hich are assignable to oxidized, quaternary or pyrrolic, andp yridinic N, respectively.…”

“…The N1ss pectrum of pristine chiral chitin exhibitsapeak at 400.2 eV,w hich is assigned to the acetamideN .T he N1ss pectrum showed three representative N-doped carbonp eaks after hydrothermalt reatment, at 402.1, 400.9,a nd 398.2 eV,w hich are assignable to oxidized, quaternary or pyrrolic, andp yridinic N, respectively. [49] Collectively,t he XPS results reaffirm the surface carbonization of chiral chitin by the HTC method.…”

Free-Standing PVDF/Reduced Graphene Oxide Film for All-Solid-State Flexible Supercapacitors towards Self-Powered Systems

“…From the obtained results, it is evident that the output of the PVDF/sodium niobate nanogenerator is highly dependent on the applied compressive force and directly proportional to its piezo-voltage. The electrospun PVDF/sodium niobate mat as the active piezoelectric layer shows enhanced output compared with the other reported piezoelectric nanogenerators and the improved performance is due to the following reasons: (i) high ferroelectric property of the PVDF and sodium niobate results in the enhancement of the piezoelectric property of the composite, (ii) high voltage applied in the fabrication methodology, which enhances the arrangement of dipoles in the prepared composite mat [38,39]. These results highlight that the electrospun PVDF/sodium niobate nanofibrous nanogenerator with improved piezoelectric output will be a promising candidate as a power source for the self-charging systems.…”

“…From Figure 4B it is evident that the device undergoes fast charging and discharging at higher current, whereas at the lower current, better charging and discharging profiles were obtained for the PVDF/reduced graphene oxide SSC device [49]. The specific capacitance (C) of the PVDF/reduced graphene oxide SSC device was calculated using the relation [39]:…”