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

摘要

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 RuO_2 increased with increase in the annealing temperature from 250 deg C to 400 deg 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 percent 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).