Synthesis of High Value-added Carbide Materials (MXenes) from Recycled Oxides

The recycling of waste resources, such as spent catalysts, primarily involves leaching and extracting metal components via smelting.These metal components are then recovered as salts, such as sulfates and nitrates.When crystallization occurs during the calcination of the recovered salts, the salts are converted into oxides, which are then reduced to form metals or ceramic materials.Common reducing agents used in oxide reduction include hydrogen and carbon, and metal powders are obtained upon reduction.Carbide synthesis can occur if the recycled element is a transition metal and carbon is used as the reducing agent.Despite being ceramic materials, transition metal carbides exhibit excellent conductivity owing to their metallic bonding.Recently, MXene, a two-dimensional transition metal carbide, has gained attention for electromagnetic wave shielding, secondary battery electrodes, and water purification owing to its electrical conductivity and large surface area.This study developed a process for synthesizing high-value MXene materials from waste resources.The properties of these MXenes were evaluated to confirm the potential of using waste resources as raw materials for MXenes.