• • CoNi-ZIF/Hem photoanode achieves a photocurrent density of 1.09 mA cm−2 at 1.1 V vs. RHE, representing a significant improvement over bare hematite, which typically delivers <0.5 mA cm−2 under similar conditions, enabling lower energy input for solar-driven biomass upgrading.
• • In a PEC flow-cell reactor, the system attains ~99% HMF conversion and ~98% FDCA yield within 2 hours under 1 sun illumination, demonstrating industrially relevant productivity for value-added chemical synthesis.
• • The CoNi-ZIF decoration enhances TEMPO adsorption and charge transfer, as confirmed by experimental and theoretical analyses, leading to a 2.5-fold increase in photocurrent density compared to undecorated hematite, directly addressing the bottleneck of sluggish surface kinetics.
• • The photoanode exhibits versatility for TEMPO-mediated oxidation of various aldehyde-containing biomass-derived compounds, expanding the scope of PEC biomass valorization beyond HMF, which is critical for biorefinery integration.