Synthesizing Pt-Ni/C Nanoframes electrocatalyst using the solvothermal and in-house developed method for PEM fuel cells

Abstract

As South Africa moves towards the production and storage of green energy sources, proton exchange membrane (PEM) fuel cells have been characterized as promising energy sources for transportation, heating, and power sources and have an efficient energy conversion that does not allow greenhouse gas emissions. However, to improve the energy efficiency and to reduce the system cost, and make it suitable for large-scale commercialization, precious metal catalyst needs to be developed with improved catalyst activities for PEM fuel cells. Due to the high cost of platinum, platinum alloy nanostructures have been investigated for use as an electrocatalyst in PEM fuel cells. Platinum-nickel alloy nanostructures in previous research studies have shown 36- and 22-times enhancement in mass and specific activity respectively, towards the cathodic oxygen reduction reaction (ORR) in PEM fuel cells and for the methanol oxidation reaction (MOR) in direct methanol fuel cell (DMFC) than the Pt/C catalyst. Therefore, this research focused on developing rich Pt-skin platinumnickel nanoframes which were synthesized using solvothermal and in-house developed methods. The intermediate products were etched to remove the interior using either a weak acid or an oxidative acid for comparison. The final product was supported by Vulcan XC-72 at a loading of 20 wt. % Pt-Ni. The properties of Pt-Ni/C will be characterized and evaluated to determine if the nanoframes are formed. The preliminary results for the X-ray diffraction pattern showed that the structure of Pt-Ni contracted and affected the catalyst properties. The catalytic activities were determined by electrochemical methods using thin-film RDE measurements, the results indicated that Pt-Ni as-synthesized has higher specific activity at 900 mV versus RHE. The specific and mass activity of the oxygen reduction reaction for Pt-Ni/C will be compared to the activities of the current high-performing Pt/C catalyst.