Abstract
A large amount of biomass straw waste is generated every year in the world, which can cause serious environmental pollution and resource waste if disposed of improperly. At present, biomass-derived porous carbon materials prepared from biomass waste as a carbon source have garnered attention due to their renewability, huge reserves, low cost, and environmental benevolence. In this work, high-performance carbon materials were prepared via a one-step carbonization-activation method and ball milling, with waste tobacco straw as precursor and nano-ZnO as template and activator. The specific surface area and porous structure of biomass-derived carbon could be controlled by carbonization temperature, which is closely related to the electrochemical performances of the carbon material. It was found that, when the carbonization temperature was 800 °C, the biochar possesses maximum specific surface area (1293.2 m2·g−1) and exhibits high capacitance of 220.7 F·g−1, at 1 A·g−1 current density in a three-electrode configuration with 6 M KOH aqueous solution. The capacitance retention maintained about 94.83% at 5 A·g−1 after 3000 cycles. This work proves the porous biochar derived from tobacco straws has a great potential prospect in the field of supercapacitors.
Highlights
Based on our previous work [37], compared with carbon materials directly prepared at different pyrolysis temperatures, the biochar (TC-800) obtained directly by pyrolysis at 800 ◦ C had the better performance, so TC-800 was used as the control group
The convex part of TCZn-7000 s edge is smooth with almost no pores, while the concave part is rough with few vesicles (Figure 1c,d), which may be due to insufficient carbonization temperature and incomplete carbonization
With tobacco straw as a carbon source and nano-ZnO as a hard template and activator, tobacco straw-derived porous activated carbon was successfully prepared by one-step
Summary
According to the China Statistical Yearbook 2019, China had produced about 8.65 × 109 tons of straw in 2019 [4], which occupied a large part of the total biomass resources in China, and this proportion will continue to rise in the future. Only a small amount of straw waste was being recycled, used as feed and fertilizer materials [5,6]. The decay of straw waste would absorb a large amount of nitrogen, phosphorus and potassium and lead to a decrease in soil fertility, while open burning would produce a large amount of carbon dioxide and other pollutants, leading to serious environmental pollution, and causing waste of renewable resources due to its renewability [7,8,9]. Promoting the comprehensive utilization of straw resources and transforming into high added value materials are of great practical significance for environmental protection, resource conservation and economic development
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