Perfect Carbon Balance in Electrooxidation of 5‐Hydroxymethylfurfural to Formic Acid Over Fe‐MoS ₂

ABSTRACT The selective catalytic conversion of biomass‐derived 5‐hydroxymethylfurfural (HMF) into high‐value chemicals represents a critical pathway toward sustainable chemical synthesis and carbon neutrality. However, precise control over the oxidation degree to avoid over‐oxidation to CO ₂ remains a formidable challenge. Herein, we report a two‐dimensional (2D) Fe‐MoS ₂ catalyst that enables highly selective electrooxidation of HMF to formic acid (FA) with near‐complete carbon retention. Leveraging the unique electronic structure of the MoS ₂ substrate, the Fe‐MoS ₂ catalyst achieves a FA yield of 86% and a Faradaic efficiency of 95% at an applied potential of 1.52 V vs. RHE, alongside excellent cycling stability and a nearly 100% carbon balance. Mechanistic investigations reveal that the high work function and suitable valence band position of Fe‐MoS ₂ create an electron‐rich interface that stabilizes carboxylic acid intermediates, while its large specific surface area and mesoporous architecture physically suppress over‐oxidation. Density functional theory (DFT) calculations further demonstrate a lower energy barrier for FA stabilization, promoting selective oxidative bond cleavage. This work highlights the critical role of modulating catalytic selectivity for providing 100% carbon balance in biomass valorization.