Molten salt electrosynthesis of Cr₂AlC-derived porous carbon for supercapacitors

Porous carbon is the most extensively investigated electrode material for supercapacitors. In this work, Cr₂AlC-derived porous carbon (Cr₂AlC-CDC) has been facilely synthesized by an electrochemical etching process in molten salts. The electrochemical processes with different etching parameters were systematically investigated, and the result shows that the Cr₂AlC-CDC obtained at 600 °C and 3.0 V exhibits an amorphous carbon structure with micro/mesopores and high specific surface area (1343 m²/g). In addition, higher temperature would increase the graphitization degree of CDC. The formation process of Cr₂AlC-CDC was also theoretically investigated by the density functional theory (DFT) method, and the intermediate products were experimentally characterized as well as compared to the DFT result. It is found that the reaction mechanism typically contains the electro-oxidation process and the electrochemical etching process. Furthermore, the specific capacity of the Cr₂AlC-CDC obtained at 600 °C can reach 183 F g^-1 at 500 mA g^-1 and remains at 98.2% after 5000 cycles, demonstrating excellent electrochemical performance for supercapacitors. The electrochemical etching process in molten salt has been proved to be a promising sustainable method for synthesizing CDC materials for supercapacitors.