Precise Engineering of Asymmetric Tri-Active Sites by Symbiotic Strategy for Photocontrolled Directional Reforming of Biomass.

Sunlight-driven production of high-value chemicals from renewable resources represents a pivotal driver toward achieving sustainable energy supply. However, fundamental barriers include inadequate use of light energy and insufficient understanding of reactive oxygen species (ROS) regulating mechanisms in photocatalytic processes. To address this, a novel symbiotic strategy for the design of Cu/TiO single-atom catalysts (SACs) supported by density functional theory (DFT) calculations was proposed. The developed catalyst achieved nearly 100% conversion and selectivity for the directional photooxidative transformation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) or 2,5-furandicarboxylic acid (FDCA) under both vis-light and UV-vis light conditions. Importantly, compared to previous works, this catalyst exhibited the highest photooxidation activity reported to date while effectively suppressing the over-oxidation of HMF to CO. Mechanistic investigations revealed that rational construction of Cu single-atoms (SAs) could effectively create the asymmetric Cu-Ov-Ti structure, which significantly enhanced the activation of O and HMF, facilitating generation of oxygen vacancy (Ov) and Ti. Furthermore, Cu SAs served as hole (h) extractors in the photooxidation process, promoting rapid charge carrier transfer and ROS formation. The applicability of this developed strategy was further demonstrated for photooxidative conversion of various bio-feedstocks, including HMF and alcoholic substrates, indicating its great potential for harnessing light energy for sustainable valorization of biomass into high-value chemicals.