Abstract
Bio-based activated carbons with very high specific surface area of >3.000 m² g−1 (based on CO2 adsorption isotherms) and a high proportion of micropores (87% of total SSA) are produced by corncobs via pyrolysis and chemical activation with KOH. The activated carbon is further doped with different proportions of the highly pseudocapacitive transition metal oxide RuO2 to obtain enhanced electrochemical properties and tune the materials for the application in electrochemical double-layer capacitors (EDLC) (supercapacitors). The activated carbon and composites are extensively studied regarding their physico-chemical and electrochemical properties. The results show that the composite containing 40 wt.% RuO2 has an electric conductivity of 408 S m−1 and a specific capacitance of 360 Fg−1. SEM-EDX, XPS, and XRD analysis confirm the homogenous distribution of partly crystalline RuO2 particles on the carbon surface, which leads to a biobased composite material with enhanced electrochemical properties.
Highlights
The last two centuries were characterized by rapid industrial and technological progress based on fossil resources like oil, gas, and coal
The different thermal treatments conducted with the corncob to obtain the activated carbon led to a drastic increase of the carbon content and a decrease of the other elements as well as ash
The reduction of the ash content is a consequence of reactions between the inorganic components in the biomass and the KOH leading to soluble compounds [9]
Summary
The last two centuries were characterized by rapid industrial and technological progress based on fossil resources like oil, gas, and coal. It is undisputable that this fossil resource base will not last for a further 200 years. A lot of research has been performed and much remains in order to create a new sustainable and reliable resource base. That is exactly what the concept of bioeconomy is aiming at—the development of new materials based on renewable resources which are ecologically and socially acceptable, and economically feasible [1]. One possible application for such new materials can be found in the large field of energy storage, which becomes increasingly important especially in times of renewable energy technologies which lack reliable storage systems or electric mobility. Supercapacitors or electrochemical double-layer capacitors (EDLC) are playing a key role in this context as they close the gap between batteries and conventional capacitors by providing high specific
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