Synergy of non-precious Co single atom sites and NiO support in catalytic transfer hydrogenation

The catalytic transfer hydrogenation (CTH) of furfural (FF) to furfuryl alcohol (FA) plays a key role in biomass valorization by transforming a renewable platform molecule into a high-value chemical used in resins and polymers. By using alcohols instead of pressurized H 2 , the process enhances safety and energy efficiency. However, the use of non-precious metal single atoms (NPM-SAs) catalysts in CTH of FF to FA under mild conditions remains underexplored. In this study, Co single atoms (Co SAs) were anchored onto a NiO support using a straightforward one-pot NaBH 4 hydrolysis-reduction method, avoiding the high-temperature pyrolysis. The developed Co SAs/NiO catalyst achieved 97% FA selectivity with 99% FF conversion at 120 °C under 1   bar of Ar. FA productivity reached 18.9 mol FA mol Co −1 h −1 and increased to 37.8 mol FA mol Co −1 h −1 when Ar was replaced with an atmospheric H 2 , achieving the highest FA productivity under the milder reaction conditions among all the reported Co-based catalysts. Structural and mechanistic studies using XANES, FT-EXAFS, TEM, in situ DRIFT-IR, and kinetic experiments revealed a strong synergy between Co SAs and the NiO support. Co−O 3 single atoms anchored at oxygen vacancies on the NiO support acted as the key active sites, facilitating the reaction via a “ Meerwein-Ponndorf-Verley ” mechanism. Compared to NiO and Co nanoparticles, Co SAs enhanced FF and isopropanol adsorption with a facilitated FA desorption, lowering the reaction barrier and enhancing the overall efficiency. Additionally, the catalyst demonstrated an excellent stability over eight consecutive cycles without metal leaching and proved effective for CTH of various aldehydes. This study highlights the potential of NPM-SAs catalysts synthesized by a simple method for efficient and selective CTH reactions under mild conditions.