Microwave-assisted synthesis of bi-functional activated carbons from rhus coriaria kernels for supercapacitor and hydrogen production applications

In the quest for sustainable economic and environmental development, the circular economy is gaining more and more attention. The main advantages of activated carbon materials made from various waste products are their wide availability, low cost, and potential to reduce waste. This thesis involved treating degreased sumac kernels (SMC) with phosphoric acid (H3PO4) for catalyst synthesis, followed by microwave carbonization. We carried out optimization studies with parameters such as chemical activator type and ratio, impregnation time, microwave power, and carbonization time to synthesize the catalyst with the highest catalytic performance. We obtained the catalyst with the most active catalytic activity (SMC-P-cat) by first preparing the sample in the ratio of SMC:H3PO4 (1:1) in an oven at 80 °C for 36 s, and then carbonizing it with a microwave at 1000 watts for 10 minutes. We determined the maximum hydrogen production rate of 28513 mL/min.gkat at 30 °C during the SMC-P-kat-catalyzed 2.5% NaBH4 methanolysis reaction. We calculated the activation energy for SMC-P-kat to be 37,71 kJ/mol. SEM-EDX, BET, XRD, and FTIR analysis techniques were used for the characterization of SMC-P-kat. In the second stage of the study, SMC-P-coat was used as an electrode for supercapacitor applications. The electrochemical performances of the prepared electrodes were tested at room temperature using galvanostatic charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy techniques, and the capacity and stability of the electrodes were calculated. At current densities of 1 A/g, 2 A/g, 3 A/g, and 4 A/g, 492,54, 459,01, 439,19, and 430,96 F/g were obtained from the electrodes of SMC-P-cat sample, respectively. After 1000 charge-discharge cycles at 4 A/g current density, the SMC-P-cat electrodes maintained 96,72% of the initial capacitance, providing excellent cycling stability. The results obtained showed that the activated carbon produced by microwave-assisted carbonization has a high hydrogen production rate, and the electrodes may constitute an important alternative for energy storage devices in the future due to their superior cyclic stability and low cost advantages.