Institut für Agrartechnik

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Browsing Institut für Agrartechnik by Classification "540"

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    Activated carbon from corncobs doped with RuO2 as biobased electrode material
    (2021) Hoffmann, Viola; Rodriguez Correa, Catalina; Sachs, Saskia; del Pilar Sandoval-Rojas, Andrea; Qiao, Mo; Brown, Avery B.; Zimmermann, Michael; Rodriguez Estupiñan, Jenny Paola; Cortes, Maria Teresa; Moreno Pirajan, Juan Manuel Carlos; Titirici, Maria-Magdalena; Kruse, Andrea
    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.
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    Binder‐free N‐functionalized carbon electrodes for oxygen evolution reaction
    (2023) Song, Feihong; Straten, Jan W.; Lin, Yang‐Ming; Ding, Yuxiao; Schlögl, Robert; Heumann, Saskia; Mechler, Anna K.
    The oxygen evolution reaction (OER) is one of the bottlenecks of electrochemical water splitting. Metal‐free carbons from biomass are highly abundant and can be easily synthesized. Their low price, high conductivity and functionalization makes them promising materials. Herein, we report about free‐standing carbon electrodes as electrocatalysts for the OER. In contrast to powder‐based catalysts, free‐standing electrodes not only avoid additives, but also facilitate post analysis and better reflect industrial conditions. Here, the performance of pure carbon electrodes is compared to those of N‐functionalized ones. Utilizing several analytical techniques, the difference in performance can be rationalized by physical properties. Especially, the analysis of the gaseous products is shown to be of crucial importance. It reveals that N‐doped carbons generate more oxygen and are more robust against carbon corrosion. This illustrates the importance of measuring selectivity especially for carbon electrocatalysts, as higher currents do not necessarily result in higher catalytic activity.