Structure–Activity Relationship of CeO ₂ on <i>tert</i> -Butyl Hydroperoxide-Mediated Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid

The sustainable production of biobased fuels and chemicals necessitates energy-efficient catalytic processes for biomass upgrading. As a pivotal biorefinery platform compound, 2,5-furandicarboxylic acid (FDCA) synthesis via 5-hydroxymethylfurfural (HMF) oxidation requires highly active catalytic systems for high-yield production under mild conditions. This study systematically investigates the structure–activity relationship of morphology-controlled cerium oxide (CeO2) in tert-butyl hydroperoxide (TBHP)-mediated oxidation of HMF to FDCA using Au/CeO2 catalysts. Remarkably, the rod-shaped Au/CeO2 catalyst exhibited exceptional performance with 82.59% FDCA yield achieved within merely 2 min at 90 °C, significantly outperforming cubic (22.59%) and octahedral (10.61%) counterparts. Through comprehensive characterization, we established that the enhanced catalytic efficiency directly correlates with the facet-dependent oxygen vacancy (VO) concentration. The rod-CeO2 predominantly exposing (110)/(100) facets demonstrated the highest VO density, which facilitated optimal Au nanoparticle dispersion (2.99 nm) and catalytic activity. In contrast, cubic and octahedral CeO2 with lower VO concentrations suffered from Au nanoparticle aggregation, leading to a diminished performance. Kinetic studies revealed a sequential oxidation pathway (HMF→HMFCA→FFCA→FDCA), where the HMFCA→FFCA transition was identified as the rate-determining step. The catalyst maintained excellent stability (>78% FDCA yield after five consecutive cycles). These findings provide fundamental insights into facet-dependent catalysis in peroxide-mediated oxidation systems and establish actionable design principles for morphology-controlled catalysts in next-generation biomass valorization technologies.