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In this work, plane tree seed-based activated carbons were characterized in detail for a variety of applications. The particularly important area of application would be in the artificial photosynthesis. After carbonization process of biomass precursor at 650°C, the resulting preliminary activated carbons were activated at various temperatures. The activated carbons were characterized by oxygen functionalities (a particularly important role has ester oxygen groups) which provide a unique microstructure. The chemical compositions of as-prepared activated carbons were analyzed through Fourier transform infrared and Raman spectra as well as gas chromatography–mass spectroscopy analysis, while morphology was observed by scanning electron microscopy analysis. Applied analysis showed that detected graphite mainly becomes uniformly nanocrystalline system. The current study also explored the applicability of carbon material obtained from plane tree seed as a potential gaseous adsorbent. The characterization showed that the tested material contains both mesopores and micropores, and this should be advantageous for the gas sorption process, since mesopores may provide low-resistant pathways for the diffusion of CO2 molecules, while the micropores are the most suitable for trapping of CO2. The sorption process analysis (including adsorption/desorption isotherms behavior) shows indication that the rate-limiting step of CO2 adsorption onto activated carbon is probably governed by diffusion-controlled process, especially at temperatures below 850°C.

The development of carbon materials with desirable textures and new aqueous electrolytes is the key strategy to improve the performance of supercapacitors. Herein, a deep eutectic solvent (DES) was used for in situ templating of a carbon material. A carbon material was characterized (XRD, N2-physisorption, FTIR, SEM and EDS) and used as an electrode material for the first time in multivalent-based supercapacitors. In situ templating of carbon was performed using a novel DES, which serves as a precursor for carbon and for in situ generation of MgO. The generation of MgO and its roles in templating of carbon were discussed. Templating of carbon with MgO lead to an increase in surface area and a microporous texture. The obtained carbon was tested in multivalent-ion (Al3+ and Mg2+) electrolytes and compared with H2SO4. The charge-storage mechanism was investigated and elaborated. The highest specific capacitance was obtained for the Al(NO3)3 electrolyte, while the operating voltage follows the order: Mg(NO3)2 > Al(NO3)3 > H2SO4. Electrical double-layer capacitance (versus pseudocapacitance) was dominant in all investigated electrolytes. The larger operating voltage in multivalent electrolytes is a consequence of the lower fraction of free water, which suppresses hydrogen evolution (when compared with H2SO4). The GCD was experimentally performed on the Al(NO3)3 electrolyte, which showed good cyclic stability, with an energy density of 22.3 Wh kg−1 at 65 W kg−1.