Combined EC-NMR and In Situ FTIR Spectroscopic Studies of Glycerol Electrooxidation on Pt/C, PtRu/C, and PtRh/C

Glycerol, a byproduct of biodiesel production, is an industrial waste because of its excess yield. Electro-oxidation of glycerol is a promising way to utilize glycerol-through harvesting electric energy as fuels in a fuel cell or hydrogen as sacrificial agent in electrolysis cell-while generating valuable chemicals. Here, we report a detailed mechanistic study of the glycerol electrooxidation reaction (GOR) on a series of Pt/C, PtxRuy/C, and PtxRuy/C nanocatalysts synthesized by NaBH4 reduction. The EC cyclic voltammetry characterization indicates that alloying Ru with Pt greatly enhanced the GOR activity, especially at low potential, but not as much with alloying Rh, as compared with Pt/C. In situ FTIR and C-13 NMR spectroscopies were used to investigate the GOR mechanism at a molecular level. The results demonstrate that the selectivity of products depends on the type of catalysts and the oxidation potential. Although both PtRu/C and PtRh/C could accelerate the oxygen insertion reactions that led to higher selectivity of carboxylic acids, tartronic acid was more favored at high potential on the PtRh/C surface.