Ambient-condition electrochemical upgrading of water-soluble bio-oil to bio-fuel via hydrogen transfer and synergistic catalysis of multimetallic nanoparticles

Bio-oil, a carbon-rich liquid from the pyrolysis of renewable biomass, holds potential as a petroleum substitute that can be upgraded to bio-fuels and high-value chemicals. Electrochemical upgrading offers milder conditions, avoiding the harsh requirements and catalyst deactivation of thermochemical upgrading. However, most organics in bio-oil have hydrogenation potentials above hydrogen evolution potentials, generally resulting in severe hydrogen evolution and low Faradaic efficiency. Here, we report an efficient and mild electrochemical system for the direct upgrading of real water-soluble bio-oil. By leveraging hydrogen-transfer catalysis and synergistic catalysis of multimetallic nanocatalysts, we enhance hydrogenation while suppressing hydrogen evolution, achieving bio-oil-to-bio-fuel conversion under ambient conditions. Major water-soluble bio-oil components show > 99 % conversion at 100–500 mA cm⁻², yielding saturated cyclic compounds (e.g., cyclohexane, cyclohexanol, cyclopentanol). Notably, this process achieved a Faradaic efficiency of 74.12 % within the first 30 min at 100 mA cm⁻². Combined theoretical and experimental analyses reveal competitive hydrogenation behaviors among water-soluble bio-oil components and elucidate the underlying cooperative catalytic mechanisms on the multimetallic surfaces. This work represents an important step toward the mild, efficient, and practical upgrading of real bio-oil.