Figure 1. Synthesis of OMCs.

A proposed mechanism for the mechanochemical assembly mediated by coordination crosslinking of tannin, a biomass-derived polyphenol, with divalent metal ions in the presence of Pluronic triblock co-polymers PEO–PPO–PEO. First, the PEO–PPO–PEO and tannin are ball milled for 0.5 h, forming a brown gel. Selected metal acetates are then added to the miller, resulting in homogeneous gel nanocomposites after a short milling time (0.5 h). After carbonization in a N₂ atmosphere, pure OMCs, or metal NP OMCs are obtained depending on the boiling point of the reduced metal species. For example, metallic Zn can evaporate during high-temperature treatment.