O₂-H₂O₂ high-efficient co-oxidation of carbohydrate biomass to formic acid via Co₃O₄/C nanocatalyst

The conversion of biomass to chemicals/fuels has emerged as a valuable solution that offers both environmental and economic benefits, with the transformation of carbohydrate into formic acid garnering escalating scholar interest. However, the relative limited efficiency of catalyzed-oxidation or expensive cost of H₂O₂ and alkali in wet hydrothermal oxidation impose limitations on industrialization. This paper proposed a new idea for formic acid production by O₂-H₂O₂ co-oxidation of carbohydrate. A two-step reaction method was developed, where the initial step is engineered to regulate the carbon chain cleavage of carbohydrates to augment the production of active intermediate. Oxygen was employed in the subsequent step as effective oxidant through free radical mechanism, resulting in a formic acid yield of 82.6%. Theoretical calculation, intermediates detection and real time EPR confirmed the reaction mechanism. Finally, the universality of the reaction was verified by using disaccharides and polysaccharides such as cellulose as substrates.