Monodisperse Condensed Tannin and Derived Carbon Nanospheres Featuring Well-Defined Surface-Structured Metal Species

Direct synthesis of monodispersed nanospheres from heterogeneous biopolymers remains a current challenge within materials science. Here, we introduce the assembly of uniform and size-tunable condensed tannin (proanthocyanidin) nanospheres (TNSp) via a hydrogen bonding-driven hydrophobic assembly that takes place in aqueous medium and ambient conditions. Uniform particles are formed by a gradual increase in tannin-amine concentrations in the reaction system, which regulates nucleation and growth via supramolecular interactions. The phenolic-amine rich surface of the nanospheres allows a precise structuring of metal species (e.g., Pt, Co, Ni), thus ensuring high dispersion, uniform particle size, and suppressed sintering of the metal species (1-2 nm) during pyrolysis. Derived carbon particles with surface-anchored Pt nanoparticles (Pt-TNSpC) are then demonstrated as high performance catalysts in the electro-hydrogenation of guaiacol, holding performance surpassing that of Pt/C catalyst. Nevertheless, life cycle assessment revealed a significantly lower carbon footprint against benchmark catalysts (1770 kg CO₂-eq.·kg^-1 vs. 11510-82660 kg CO₂-eq.·kg^-1), alongside enhanced material circularity. This work establishes a sustainable strategy for converting renewable biobased feedstocks into precision nanostructured particles for high performance catalysis. We envision these metal-functionalized tannin-derived particles to find use in various fields in which metallic functionalities play a role.