Abstract
In current times, CO2 capture and lightweight energy storage are receiving significant attention and will be vital functions in next-generation materials. Porous carbonaceous materials have great potential in these areas, whereas most of the developed carbon materials still have significant limitations, such as nonrenewable resources, complex and costly processing, or the absence of tailorable structure. In this study, a new strategy is developed for using the currently underutilized lignin and cellulose nanofibers, which can be extracted from renewable resources to produce high-performance multifunctional carbon aerogels with a tailorable, anisotropic pore structure. Both the macro- and microstructure of the carbon aerogels can be simultaneously controlled by carefully tuning the weight ratio of lignin to cellulose nanofibers in the precursors, which considerably influences their final porosity and surface area. The designed carbon aerogels demonstrate excellent performance in both CO2 capture and capacitive energy storage, and the best results exhibit a CO2 adsorption capacity of 5.23 mmol g–1 at 273 K and 100 kPa and a specific electrical double-layer capacitance of 124 F g–1 at a current density of 0.2 A g–1, indicating that they have great future potential in the relevant applications.
Highlights
In the recent decades, carbonaceous porous materials have received great research interest because of their large surface area, high porosity, low density, and sufficient electrical conductivity.[1]
Studies have focused on investigating the CO2 adsorption behavior of activated carbon and other porous carbonaceous materials derived from nitrogen-rich synthetic polymers, such as lysine-catalyzed resorcinol−formaldehyde (RF) and polypyrrole.[5−7] because of the burgeoning demand for lightweight energy storage devices, the electrochemical properties of different carbonaceous aerogels as electrodes in such devices have been investigated over the past decade.[8−15] Aerogel electrodes can be carbonized from various precursors, including RF,[8] melamine sponges,[11] watermelon,[9] bacterial cellulose,[10] and regenerated cellulose.[12,13]
The kraft lignin and TEMPO-oxidized CNFs (TOCNFs) suspension were mixed with distilled water to generate lignin/TOCNF suspensions (Figure 1b) with various TOCNF concentrations (8, 10, and 12 wt % of the total dry weight)
Summary
Carbonaceous porous materials have received great research interest because of their large surface area, high porosity, low density, and sufficient electrical conductivity.[1]. Using the water-soluble kraft lignin together with the aqueous TOCNF suspension allows to perform the ice-templating process, in which the growth of unidirectional ice crystals in the suspension can bring anisotropic macroporous structure to the aerogel precursors after freeze-drying.[25] This unique structure is expected to be remained in the derived carbon aerogels after carbonization, leading to the formation of hierarchical porous structure including pores at all length scales, i.e., macro-, meso-, and micropores. By varying the TOCNF content, the surface area of the carbon aerogels can be adjusted, which affects their final CO2 adsorption capacity and EDL capacitance This strategy offers new possibilities for the development of porous carbonaceous materials from renewable carbon resources with adjustable structure that are environmentally sustainable with remarkable performance in the relevant applications
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