Triphase Reaction System with Micro- and Nano-scale Hierarchical Gas Channels for Efficient Photocatalytic Achmatowicz Rearrangement

Abstract Photocatalytic Achmatowicz rearrangement of furfuryl alcohol (FFA) is a sustainable route to synthesizing high-value pyranone (PN) bioactive intermediates. The conversion of O2 to singlet oxygen (1O2) is critical for selective PN formation. Constructing a gas–liquid–solid triphase system offers an alternative strategy to boost such O2-involved catalysis. However, current triphase systems are typically fabricated by depositing hydrophilic catalysts on superhydrophobic substrates. The triphasic interface only forms at the regions where the catalyst is in contact with the substrate, whereas O2 inside the catalyst layer still suffers from sluggish diffusion and insufficient local concentration. Herein, we design and construct a triphase system with micro- and nano-scale hierarchical gas channels for photocatalytic Achmatowicz rearrangement. Core–shell silicalite-1@TiO2 (S-1@TiO2) is synthesized by coating TiO2 on zeolite silicalite-1 (S-1). The internal nano-scale hydrophobic channels of S-1 act as O2 storage reservoirs and transport pathways, forming localized microscopic triphase interfaces within the catalyst layer. A hierarchical triphase interface system is constructed by further immobilizing S-1@TiO2 onto superhydrophobic substrates with micro-scale pores, enabling continuous atmospheric O2 to diffuse into the nano-scale hydrophobic channels. Benefiting from the synergistic effect of micro- and nano-scale hierarchical gas channels, the hierarchical triphase system exhibits much improved PN production and selectivity, and its catalytic active site utilization efficiency reaches 5-fold that of conventional triphase systems. This work provides insights into the rational regulation of triphase microenvironments for the construction of high-efficiency photocatalytic systems.