Enhanced activity of PtSn/C anodic electrocatalyst prepared by formic acid reduction for direct ethanol fuel cells

The Pt3Sn/C catalyst with high electrochemical activity was synthesized under optimizing preparation conditions. The surface of carbon support pretreated by strong acid contains many O–H and CO groups, which will increase the active sites of PtSn/C catalysts. The catalyst structure was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and temperature programmed reduction (TPR). The co-reduction of Pt4+ and Sn2+ ions causes Sn to enter Pt crystal lattice to form PtSn alloy whose surface, however, contains tin oxides with Sn4+ and Sn2+ valences, which can promote the ethanol oxidation. The crystallinity of PtSn decreases with the reduction of the atomic ratio of Pt:Sn. By prolonging the reaction time of formic acid, the forward anodic peak current of ethanol oxidation reaches 16.2 mA on the Pt3Sn/C catalyst with 0.025 mg Pt loading.