Bioinspired pathway engineering in Au nanoclusters: Dopamine ligands as molecular switches for exclusive photocatalytic H2O2 generation

Solar-driven hydrogen peroxide (H₂O₂) production offers a sustainable alternative to the energy-intensive anthraquinone process, yet conventional photocatalysts suffer from poor selectivity and uncontrollable reaction pathways. Inspired by catechol oxidase enzymes, we design dopamine-grafted lipoic acid-protected gold nanoclusters (DA-LA-Au NCs) that shift photocatalytic active sites from the metal core to redox-active ligands. This ligand-centric architecture leverages dopamine’s reversible catechol/quinone interconversion to gate a biomimetic proton-coupled electron transfer (PCET) pathway, enabling exclusive 2e⁻ oxygen reduction with near-100% H₂O₂ selectivity while completely suppressing superoxide radical (·O₂⁻) generation. Transient absorption spectroscopy and molecular dynamics confirm enhanced electron transfer kinetics and O₂ enrichment at ligand sites. Encapsulation in ZIF-8 stabilizes the system, achieving a record H₂O₂ yield of 1198 μmol/L under visible light without sacrificial agents and a 0.39% solar-to-chemical conversion efficiency, surpassing most reported photocatalysts. This "ligand-as-catalyst" strategy merges enzymatic precision with nanocluster functionality for sustainable oxidant synthesis.