Morphology Engineering Derived <scp>CoOOH</scp> With Tunable Oxygen Vacancies for Potential‐Dependent Selective Electrooxidation

The electrooxidation of 5‐hydroxymethylfurfural (HMF) represents a crucial route for sustainable biomass valorization. However, achieving oriented selectivity among oxidation products on one single catalyst remains challenging. Herein, we employed a morphology‐engineering strategy on CoFe Prussian blue analogue (PBA) precursors to derive a CoOOH catalyst for the selective electrooxidation of HMF. As the precursor morphology evolves from solid cubes to hollow boxes and further to hollow frames, the resulting CoOOH exhibits a progressive increase in oxygen vacancy density and accessible active sites. These structural features not only enhance the co‐adsorption of HMF and OH − but also accelerate the formation kinetics of the active CoOOH species, as well as significantly lower the energy barrier for HMF to HMFCA conversion at low potentials (1.10 V vs RHE) while suppressing over‐oxidation. The optimized catalyst enables a 5‐hydroxymethyl‐2‐furancarboxylic acid (HMFCA) yield of 91.0% at 1.10 V and an almost quantitative 2,5‐furandicarboxylic acid (FDCA) yield of ~100% at 1.40 V. This work demonstrates a single‐catalyst platform for the selective synthesis of multiple value‐added chemicals, establishes a clear relationship between defect density and electrocatalytic performance, and provides important guidance for the design of advanced heterogeneous electrocatalysts.