OXYGEN REDUCTION REACTION EVALUATION OF PLATINUM CATALYSTS FORMED VIA THE REACTIVE SPRAY DEPOSITION TECHNIQUE

摘要

Reactive Spray Deposition Technology (RSDT) is a fabrication process developed for the 1-step deposition of platinum catalyst, carbon support and ionomer directly onto a Nafion® membrane. The process involves pumping a platinum-organic solute dissolved in a combustible solvent through an atomizer. The spray is then combusted and nanosized particles of platinum are produced and subsequently cooled by a gas quench. Once the reaction plume is cooled a secondary set of nozzles is used to inject the carbon support and ionomer. The quench air cools the reactive zone enough to allow direct deposition onto a Nafion® electrolyte or a glassy carbon electrode. This arrangement thus realizes a process for one-step catalyst formation, dispersion onto carbon and direct deposition onto an electrolyte membrane. The independent control of the three components allows for real-time control of the carbon, platinum, and ionomer ratios in the final electrode. In this research work we examine the oxygen reduction reaction via a rotating disc three electrode set-up to understand the intrinsic activity of the as-sprayed platinum. The mass and specific activities were measured in a 0.1 M perchloric acid electrolyte under different deposition conditions and loading was verified by atomic emission spectroscopy inductively coupled plasma (AES-ICP). A range of microscopy images for visualization of the microstructure are also presented. The initial results show that the RSDT technique is capable of producing catalysts with oxygen reduction mass activity at 0.9 V of 200 mA/mg_(Pt) rotating at 1600 rpm and 30 ℃.