Alcohol reduction-mediated preparation of a nano-scale Pt/C electrocatalyst for the oxygen reduction reaction in PEM fuel cells

A nano-scale Pt/C electrocatalyst for oxygen reduction in PEM fuel cells was prepared by alcohol-mediated reduction of the PtCl62− ion complex on the carbon Vulcan XC-72. The effects of various parameters, including the types of precursor and reducing agent and their concentrations, the initial solution pH and the reaction time, were explored. The preliminary results indicated that the electrocatalyst prepared using ammonium hexachloroplatinate ((NH4)2PtCl6) as the Pt2+ source provided a similar catalytic efficiency as that prepared from hexachloroplatinic acid (H2PtCl6). The nano-scale Pt/C electrocatalyst prepared using methanol (CH3OH) as a reducing agent provided the smallest sized platinum particles with a uniform distribution in the nanometer range, a good particle dispersion and a high Pt content compared with that prepared using ethanol (C2H5OH) or 2-propanol (C3H7OH). The electrocatalyst prepared in an acidic solution yielded smaller sized platinum particles and a higher Pt content than that prepared in a basic solution. In addition, the concentration of the reducing agent and reaction time slightly affected both the Pt particle size and the Pt yield of the obtained electrocatalyst. Under apparent optimal conditions, the nano-scale Pt/C electrocatalyst had an electrochemical surface area of ∼39.7m2/g, which was ∼1.9-fold higher than that of the commercial one. The performance of the electrocatalyst was also tested in a single PEM fuel cell in a H2/O2 atmosphere where compared to a commercial electrode a lower activation loss but higher ohmic loss was observed.