Chiral Nematic Cellulose Nanocrystal/Germania and Carbon/Germania Composite Aerogels as Supercapacitor Materials

Abstract

The development of novel aerogel materials with chiral nematic ordered structures offers exciting pathways for the fabrication of multifunctional hybrid materials with enhanced functionality. Aerogels prepared from cellulose nanocrystals are especially interesting due to their unique structural properties. To promote applicability in energy storage materials, it is often necessary to incorporate metals and metal oxides into three-dimensional porous nanostructures. In this study, germania was incorporated into a chiral nematic cellulose nanocrystal aerogel using a sol–gel method. Interestingly, our approach does not disturb the order of the original chiral nematic CNC aerogels, providing hybrid aerogels with a large concentration of randomly distributed GeO2 nanoparticles and specific surface areas up to 705 m2 g–1. Carbonization of the composite material afforded a highly ordered material with no collapse during compression and good shape recovery after release. The combination of the electrochemical double layer capacitance provided by the carbonaceous skeleton and the pseudocapacitive contribution from the GeO2 nanoparticles resulted in materials with a maximum C p of 113 F g–1 that exhibited good capacitance retention. To push the boundaries of safer energy storage devices based on renewable resources, we demonstrate the preparation of an all-cellulose solid-state symmetric supercapacitor.

Silica-Assisted Controlled Engineering of Nitrogen-Doped Carbon Cages with Bulges for High-Performance Supercapacitors

“…Among the various carbonaceous materials with different morphologies, the carbon cages with a hollow core surrounded by a carbon shell morphology have unique merits for energy storage as a supercapacitor, similar to inorganic hollow spheres. , The carbon cages also exhibit the special features of a high specific surface area with abundant boundaries, pores, or edges on the outer surface. − Furthermore, the carbon cages can be further assembled into a three-dimensional (3D) hierarchical structure, which endows them with mass/charge transportation and enhanced storage capacity. − The unique 3D cages structure and morphologies enable the carbon cages to overcome the weaknesses of typical low-dimensional carbon-based materials used for energy storage, such as ultrasmall interior cavities, poor conductivity of zero-dimensional (0D) fullerenes, and the inert surface of the one-dimensional (1D) carbon nanotubes or two-dimensional (2D) graphene. , Therefore, research studies toward carbon cages have drawn much attention in the field of carbon nanomaterials for supercapacitor applications.…”

“…9−13 Among the various carbonaceous materials with different morphologies, the carbon cages with a hollow core surrounded by a carbon shell morphology have unique merits for energy storage as a supercapacitor, similar to inorganic hollow spheres. 14,15 The carbon cages also exhibit the special features of a high specific surface area with abundant boundaries, pores, or edges on the outer surface. 16−18 Furthermore, the carbon cages can be further assembled into a three-dimensional (3D) hierarchical structure, which endows them with mass/charge transportation and enhanced storage capacity.…”

Cellulose Nanocrystals/Poly(3,4-ethylenedioxythiophene) Photonic Crystal Composites with Electrochromic Properties for Smart Windows, Displays, and Anticounterfeiting/Encryption Applications

“…We speculate that after acid treatment, PEDOT:PSS aggregated in a periodically layered structure in the CP x composite coatings, which is beneficial to the fast charge transport and the shortened switching speed . Moreover, the high surface area and aspect ratio of cellulose nanocrystals and the unique chiral nematic layered structure may contribute to shortening the ion diffusion path and enlarging the available interaction area with the electrolytes as well . The chronoamperometry (CA) curves of the CP 3 composite coating before and after washing were recorded while switching the voltage from −0.6 to 0.8 V, with the time interval of 1 s at 100 mV·s –1 (Figure S15).…”

Chiral Liquid Crystalline Properties of Cellulose Nanocrystals: Fundamentals and Applications

“…The combination of the electrolytic double-layer capacitance of the carbon-containing skeleton and the pseudocapacitive contribution of the GeO 2 nanoparticles resulted in materials with a maximum C p of 113 F/g and high capacitance retention. 219 Likewise, the author of ref ( 220 ) polymerizes pyrrole in situ onto modified chiral nematic CNC sheets by covering them with a conductive polymer. TEMPO-oxidation, acetylation, desulfation, and catonization had no effect on the chiral structures.…”

“…A notable example of using CNC-embedded systems for optoelectronic applications is the production of crack-free, chiral nematic GeO 2 /CNC composite films with tunable photonic properties from the controlled assembly of germanium(IV) alkoxides with “lyotropic” liquid-crystalline CNCs in a water/dimethylformamide (DMF) mixed solvent. 219 Photonic GeO 2 /CNC composites may be transformed into semiconducting mesoporous GeO 2 /C and Ge/C copies, freestanding chiral nematic films of amorphous GeO 2 , and photonic GeO 2 /CNC composites using different pyrolysis conditions. These novel materials have applications in chiral separation, enantioselective adsorption, catalysis, sensing, optoelectronics, and lithium-ion batteries, among others.…”