A Spin-Engineered Nanozyme Overcomes the Activity-Selectivity Trade-Off for Sustainable Adhesive Production From...

Lignin, a major component of plant cell walls, is the most abundant source of natural aromatic polymers. Efficient production of its valuable degradation products requires highly selective catalysts. This study introduces a spin-state-modulated nanozyme system for precise lignin depolymerization into targeted biobased chemicals. Precise copper spin state control in two-dimensional (2D) copper-based metal organic framework (MOF) nanozymes, achieved via redox treatment and ligand exchange modulation, replicates natural laccase multicopper center spin synergy. Integrated experiments and theory reveal a volcano-shaped spin state-activity correlation, enabling synthesis of optimized nanozyme Cu(OH)₂BDC-LA-OAc (COHBLO). This material demonstrates exceptional laccase-mimicking activity, with a peak reaction rate 70 times higher than natural laccase and a 5.14-fold specific activity increase. Through laccase-like catalysis, it selectively cleaves lignin β-O-4 linkages, directionally yielding fragments rich in phenolic hydroxyl groups. Their efficient reaction with epoxy groups produces a nanolignin-based epoxy adhesive. Featuring a three-dimensional cross-linked network, this adhesive delivers superior bonding under varied conditions. Its shear strength significantly surpasses commercial phenolic resins while eliminating conventional adhesive formaldehyde emissions. This study advances 2D MOF nanozyme design and establishes an integrated pathway from controlled lignin depolymerization to high-performance adhesive production, providing key theoretical and practical foundations for biomass valorization and sustainable adhesive development.