Platinum/vivianite bifunction catalysts for DMFC

Bi-functional catalysts are used to solve the poisoning problem caused by carbon monoxide (CO) which is the intermediate of direct methanol fuel cells (DMFCs). Flower-like vivianite (Fe3(PO4)2·8H2O) spheres with diameter around 10 μm are originally used as supports of Pt to form bifunction catalysts. The cyclic voltammetry in 1 M H2SO4 indicates that the electrochemical surface area (ECSA) of Pt reduced on as-prepared vivianite (Pt/Vi) was 105, greater than 91 m2 g−1 for the commercial Pt/C. Besides, Pt/Vi reveals the less CO poisoning effects, including the greater mass activity in methanol oxidation and the lower onset potential in CO-stripping than Pt/C. These excellent performances on electrolyzes are related to the chemical state of Fe3+ and the coexistence of Pt0 and Pt2+ in Pt/Vi. The former activates the water and yields Fe-OHads at lower potential and the latter may offer an easy way of electron transition.

► Flower-like vivianite spheres are prepared and used as supports of Pt catalysts.
► The ECSA of Pt/vivianite (Pt/V) is greater than the commercial Pt/C catalyst.
► Scarce CO poisoning effect is found on Pt/V in methanol oxidation reaction (MOR).
► The mass activity of Pt/V in MOR is greater than that of the commercial Pt/C.
► The excellent performances are related to the chemical states of Fe and Pt in Pt/V.