Transition　metal-based　electrocatalysts　are　a　promising　alternative　to　noble　metal　catalysts　for　electrochemical　upgrading　of　biomass-derived　5-hydroxymethylfurfural　(HMF)　into　high-value　2,5furandicarboxylic　acid　(FDCA).　However,　the　rational　design　of　efficient　electrocatalysts　with　precisely　tailored　structure-activity　correlations　remains　a　critical　challenge.　Herein,　we　report　a　hierarchically　structured　self-supporting　electrode　(Vo-NiCo(OH)2-NF)　synthesized　through　in　situ　electrochemical　reconstruction　of　NiCo-Prussian　blue　analogue　(NiCo-PBA)　precursor,　in　which　oxygen　vacancy　(Vo)rich　Co-doped　Ni(OH)2　nanosheet　arrays　are　vertically　aligned　on　nickel　foam　(NF),　creating　an　interconnected　conductive　network.　When　evaluated　for　the　HMF　oxidation　reaction　(HMFOR),　Vo-NiCo(OH)2-NF　exhibits　exceptional　electrochemical　performance,　achieving　near-complete　HMF　conversion　(99%),　ultrahigh　FDCA　Faradaic　efficiency　(97.5%),　and　remarkable　product　yield　(96.2%)　at　1.45　V,　outperforming　conventional　Co-doped　Ni(OH)2　(NiCo(OH)2-NF)　and　pristine　Ni(OH)2　(Ni(OH)2-NF)　electrodes.　By　combining　in　situ　spectroscopic　characterization　and　theoretical　calculations,　we　elucidate　that　the　synergistic　effects　of　Co-doping　and　oxygen　vacancy　engineering　effectively　modulate　the　electronic　structure　of　Ni　active　centers,　favor　the　formation　of　high-valent　Ni3+　species,　and　optimize　HMF　adsorption,　thereby　improving　the　HMFOR　performance.　This　work　provides　valuable　mechanistic　insights　for　catalyst　design　and　may　inspire　the　development　of　advanced　transition　metal-based　electrodes　for　efficient　biomass　conversion　systems.　(c)　2025　Science　Press　and　Dalian　Institute　of　Chemical　Physics,　Chinese　Academy　of　Sciences.　Published　by　Elsevier　B.V.　and　Science　Press.　All　rights　are　reserved,　including　those　for　text　and　data　mining,　AI　training,　and　similar　technologies.