A facile synthesis of high activity cube-like Pt/carbon composites for fuel cell application

Abstract

High activity catalyst with simple low-cost synthesis is essential for fuel cell commercialization. In this study, a facile procedure for the synthesis of cube-like Pt nanoparticle (PtCube) composites with high surface area carbon supports is developed by mixing precursor of Pt with carbon supports in organic batches, hence, one pot synthesis. The PtCube grow with Vulcan XC-72 or Ketjen black, respectively, and then treated for 5.5 h at 185oC (i.e., PtCube5.5/V and PtCube5.5/K). The resulting particle sizes and shapes are similar; however, PtCube5.5/K has a larger electrochemical active surface area (EASA) and a remarkably better formic acid (FA) oxidation performance. Optimization of the PtCube/K composites leads to PtCube10/K that has been treated for 10 h at 185oC. With a larger EASA, PtCube10/K is also more active in FA oxidation than the other PtCube/K composites. Impedance spectroscopy analysis of the temperature treated and asprepared (i.e., untreated) PtCube/K composites indicates that PtCube10/K is less resistive, and has the highest limiting capacitance among the PtCube/K electrodes. Consistently, the voltammetric EASA is the largest for PtCube10/K. Furthermore, PtCube10/K is compared with two commercial Pt/C catalysts, Tanaka Kikinzoku Kogyo (TKK), and Johnson Matthey (JM)Pt/C catalysts. The TKK Pt/C has a higher EASA than PtCube10/K, as expected from their relative particles sizes (3–4 nm vs. 6–7 nm for PtCube10/K), however, PtCube10/K has a significantly better FA oxidation activity.