Size-controlled synthesis of Pt nanoparticles and their electrochemical activities toward oxygen reduction

Pt/C catalysts with high activity toward oxygen reduction reactions are fabricated in the presence of FeCl₃ as an additive to control the Pt particle size. The polyol method is used for fabrication; 20 wt% Pt/C catalysts are produced with various amounts of FeCl₃ under different fabrication conditions such as pH and temperature. Adding FeCl₃ significantly reduces Pt particle size, which is believed to occur as a result of the interference of Pt reduction rate by Fe³⁺ ions. The average Pt particle size obtained using the fabrication conditions of Pt:Fe = 1:3 (mole ratio), pH = 10, and 130 °C is around 2.0 nm, which is much smaller than that of commercial or homemade Pt/C produced in the absence of FeCl₃. The electrochemically active surface area of this catalyst is 60.6 m ²/g. The mass activities at 0.9 and 0.85 V are 15.3 and 42.7 mA/mg_Pt, respectively, which is about 1.8-2.1 times higher than those of commercial Pt/C catalysts. PEMFC test results show that the performance of the Pt/C catalyst fabricated with FeCl₃ additive is better than that of as commercial catalyst.