Boosting C3-alcohol electrooxidations by co-fueling with formic acid: A real-time quantitative nuclear magnetic resonance spectroelectrochemical study

C3-alcohols can theoretically provide high current efficiencies in direct fuel cell applications because of their intrinsically large energy densities. However, during realistic reactions, molecular multiple carbon–carbon (CCC) bonds are hardly broken, severely reducing current efficiencies. Herein, directly with commercial Pt/C as the catalyst, the operation of co-fueling with formic acid significantly enhances the current efficiencies of two types of C3-alcohols, namely, isopropanol and 1,2-propanediol. Compared with the current densities of pure C3-alcohols, those of co-fueled C3-alcohols increase maximally by 9.9 times. The reason lies in the fact that the co-fueling design facilitates the breaking of CCC bonds, as elucidated by charge distributions that are obtained via electrochemical nuclear magnetic resonance analyses. Density-functional-theory computational results indicate that the generation of OH groups adsorbed on Pt surfaces is promoted in co-fueling experiments, reducing energy barriers for breaking progress. The co-fueling strategy is capable of optimizing C3-alcohol electrooxidations in direct fuel cells and deserves extensive study.