The formation, characterization and application of starch-derived carbonaceous mesoporous materials (Starbon®) for the selective adsorption and recovery of critical metals (Au³⁺, Pt²⁺ and Pd²⁺) has been described. Starbon® successfully separated these critical metals from a mixture containing earth abundant elements (Ni²⁺, Cu²⁺ and Zn²⁺) with the consequent formation of metal nanoparticles.