Vol.:(0123456789) 1 3 Clean Technologies and Environmental Policy https://doi.org/10.1007/s10098-021-02164-2 ORIGINAL PAPER Defatted spent cofee grounds‑supported cobalt catalyst as a promising supercapacitor electrode for hydrogen production and energy storage Duygu Elma Karakaş 1  · Murat Akdemir 2  · M. R. Atelge 4  · Mustafa Kaya 5  · A. E. Atabani 3 Received: 27 January 2021 / Accepted: 14 July 2021 © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2021 Abstract The efect of several parameters, such as diferent Co 2+ ratios, burning temperatures, and burning times, was examined by using defatted spent cofee grounds (DSCG) as organic waste to obtain the most efective catalyst for producing hydrogen. Under optimum conditions, the most active catalyst/metal ratio was obtained by burning 50% Co 2+ at 400 °C for 90 min. To measure the time-dependent amounts of hydrogen, 0.1 g of DSCG-Co catalyst was dissolved in 10 mL of a methanol solu- tion containing 0.25 g sodium borohydride (NaBH 4 ) at 30 °C. The maximum hydrogen generation rate obtained from the methanolysis of NaBH 4 at 30 and 60 °C was found to be 8749 and 17,283 mL min −1 gcat −1 , respectively, and the activation energy of the catalyst was found to be 23.2 kJ mol −1 . FTIR, ICP-OES, XRD, BET, and SEM–EDX analyses were performed for the characterization of the prepared DSCG-Co-Cat catalyst. Furthermore, a supercapacitor cell was constructed by using this catalyst as an active substance for electricity storage. The specifc capacitance of the electrode at the current density of 1 A/g was calculated as 67 F/g for two-electrode systems. The results of electrochemical analysis of the prepared supercapaci- tor were found to be similar to the ideal supercapacitor curves. The obtained capacitance values are at very good levels in terms of the capacity and cost factors. The results indicated that the multifunctional capacitor-catalyst material produced by Co-doped waste cofee could constitute an important element in a hybrid system that includes capacitor and catalyst systems that can be installed in the future. * Mustafa Kaya mustafakaya2011@gmail.com * A. E. Atabani aeatabani@gmail.com; a.atabani@erciyes.edu.tr 1 Science and Technology Application and Research Center, SİÜBTAM, Siirt University, Siirt, Turkey 2 Department of Electrical and Electronics Engineering, Siirt University, Siirt, Turkey 3 Alternative Fuels Research Laboratory (AFRL), Energy Division, Department of Mechanical Engineering, Faculty of Engineering, Erciyes University, 38039 Kayseri, Turkey 4 Department of Mechanical Engineering, Faculty of Engineering, Siirt University, 56100 Siirt, Turkey 5 Department of Chemical Engineering, Siirt University, Siirt, Turkey