Selective Oxidation of Glycerol to Glycolic and Oxalic Acids for Direct Glycerol Fuel Cell

The direct glycerol fuel cell (DGFC) is a promising application, although the catalyst has limits and could be improved. This study used density functional theory (DFT) calculations to elucidate how the addition of silver (Ag) to a palladium (Pd) catalyst can change the mechanism of the glycerol oxidation reaction (GEOR). It was discovered that the glycerol easily oxidized at the primary carbon at the start of the reaction. Glyceraldehyde and glyceric acid are produced as intermediary products due to primary carbon oxidation using Pd₃–Ag₁ (111). The addition of Ag aided C–C cleavage during the reaction, converting glyceric acid to glycolic acid rather than tartronic acid. The selectivity of high-value molecules such as glycolic and oxalic acid was more likely to increase due to the early C–C splitting. At the end of the possible chemical pathways, oxalic acid or formic acid can be generated with the nine electrons that can be transferred. This work's catalyst model and mechanism can be employed with a new alloy catalyst combination and modification or tested with a different type of alcohol or polyol as fuel. DFT analysis of the mechanism allows for more flexible improvement and design in the search for novel and better catalysts.