Development of Bismuth-Modified PtPd Nanocatalysts for the Electrochemical Reforming of Polyols into Hydrogen and Value-Added Chemicals

Different PtPd nanostructured catalysts modified with bismuth have been synthesized on a carbon support. Their activity towards the glycerol electrooxidation reaction has been compared in alkaline medium, and modification with about 10 at% bismuth led to an increase in activity compared with pure metals. Pt9Bi1/C is the most active catalyst for this reaction, with an oxidation onset potential as low as 0.3 V versus RHE. The hydrogen production in a direct electrolysis cell was evaluated. The Pt9Bi1/C anode gave a hydrogen production rate of approximately 0.11 and 0.23 Nm(H2)(3)h(-1)m(-2) with an electrical energy consumption of 1.3 or 1.65 kWh(Nm(H2)(3))(-1) at 0.55 or 0.7 V, respectively. Compared with traditional water electrolysis, this is an energy saving of between 66 and 57 %. It was also shown by using in situ FTIR spectroscopy that the modification of platinum with bismuth avoids (or at least drastically reduces) C-C bond breakage, which thus increases selectivity towards value-added C3 compounds. At low potentials, glyceraldehyde is the main reaction product and at higher potentials, glyceraldehyde and dihydroxyacetone act as reaction intermediates to the formation of carboxylates.