Wood and Black Liquor-Based N-Doped Activated Carbon for Energy Application

"Sweetwoods" Lignin as Promising Raw Material to Obtain Micro-Mesoporous Carbon Materials

Biorefineries with the significant amounts of lignin as a by-product have a potential to increase business revenues by using this residue to produce high value-added materials. The carbon materials from biomass waste increases the profitability of the production of porous carbon used for sorbents and energy production. The purpose of this research is to study the chemical properties of lignin from "Sweetwoods" biorefinery as well as to characterize lignin carbonizates and activated carbons synthesized from them. This paper describes the effect of carbonization conditions (thermal or hydrothermal) on the properties of activated carbon material. It can be concluded that, depending on the carbonization method, the three-dimensional hierarchical porous structure of activated carbon materials based on "Sweetwoods" lignin, has micro- and mesopores of various sizes and can be used for number of purposes: both for high-quality sorbents, catalysts for electrochemical reduction reactions, providing sufficient space for ion mass transfer in electrodes for energy storage and transfer.

Effect of Pretreatment on the Nitrogen Doped Activated Carbon Materials Activity towards Oxygen Reduction Reaction

Nitrogen-doped activated carbons with controlled micro- and mesoporosity were obtained from wood and wastes via chemical processing using pre-treatment (pyrolysis at 500 °C and hydrothermally carbonization at 250 °C) and evaluated as oxygen reduction catalysts for further application in fuel cells. The elemental and chemical composition, structure and porosity, and types of nitrogen bonds of obtained catalyst materials were studied. The catalytic activity was evaluated in an alkaline medium using the rotating disk electrode method. It was shown that an increase in the volume of mesopores in the porous structure of a carbon catalyst promotes the diffusion of reagents and the reactions proceed more efficiently. The competitiveness of the obtained carbon materials compared to Pt/C for the reaction of catalytic oxygen reduction is shown.

Black Liquor and Wood Char-Derived Nitrogen-Doped Carbon Materials for Supercapacitors

Herein, we present a synthesis route for high-efficiency nitrogen-doped carbon materials using kraft pulping residue, black liquor, and wood charcoal as carbon sources. The synthesized nitrogen-doped carbon materials, based on black liquor and its mixture with wood charcoal, exhibited high specific surface areas (SSAs) of 2481 and 2690 m² g^-1, respectively, as well as a high volume of mesopores with an average size of 2.9-4.6 nm. The nitrogen content was approximately 3-4 at% in the synthesized nitrogen-doped carbon materials. A specific capacitance of approximately 81-142 F g^-1 was achieved in a 1 M Na₂SO₄ aqueous solution at a current density of 0.2 A g^-1. In addition, the specific capacitance retention was 99% after 1000 cycles, indicating good electrochemical stability.

Biomass-Based Oxygen Reduction Reaction Catalysts from the Perspective of Ecological Aesthetics—Duckweed Has More Advantages than Soybean

Ecological aesthetics encourages the harmonization of humans and nature. In this paper, we integrate ecological aesthetics into the development of oxygen reduction reaction (ORR) catalysts of H2/O2 fuel cells. Moldy soybean and duckweed as raw materials are adopted to prepare biomass-based ORR catalysts, both of which have advantages in activity, stability, environmental protection and resource richness over the conventional expensive and scarce noble metal-based catalysts. Therefore, duckweed is more environmentally friendly, entails a simpler preparation process and has a better catalytic performance, ultimately being more in line with ecological aesthetics.