Effects of annealing treatment and pH on preparation of citrate-stabilized PtRu/C catalyst

The annealing treatment and pH were controlled to prepare a bimetallic PtRu/C anode catalyst by the citrate-stabilized chemical reduction method. X-ray diffraction and X-ray photoelectron spectra revealed that the catalyst before the annealing treatment showed smaller size particles mainly composed of metallic platinum and hydrous ruthenium oxide. The anhydrous RuO2 increased with increase in the annealing temperature from 250 °C to 400 °C. The linear sweep voltammetry (LSV) results showed that the non-annealed catalyst had the highest current density at a given potential. Also, the particle size varied with the stabilizing pH. A homogenous catalyst was prepared at a pH of 7 in the laboratory. The particle size was about 2.39 ± 0.46 nm with 14.62 at% ruthenium in the PtRu alloy. The maximum LSV current density was 66.4 mA mg−1 PtRu at 0.45 V with an onset potential of 0.12 V (versus SCE). The catalyst when tested in a single cell DMFC produced a power density of 67.5 mW cm−2 at a current density of 240 mA cm−2.