Circular use of Pt/C through Pt dissolution from spent PEMFC cathode and direct reproduction of new catalyst with microwave synthesis

Abstract

Nanoparticulate platinum supported on high surface area carbon (Pt/C) remains the electrocatalyst of choice at the cathode of the low-temperature polymer electrolyte membrane fuel cell (PEMFCs). Recycling of the Pt/C from the spent PEMFC electrodes through environment-friendly and economic processes is of high industrial significance. Here, we report such a Pt/C recycling process involving recovery of Pt from spent PEMFC electrodes through dissolution under mild conditions followed by synthesis of Pt/C using the Pt containing dissolution bath as the Pt source. Prior to recycling, the spent PEMFC electrodes were characterized for the physical and chemical states of Pt nanoparticles (size, agglomeration, surface adsorbed species, electrochemical surface area, etc.), owing to their influence on the Pt dissolution under mild conditions. Pt from the spent electrode was recovered through dissolution in 1 M HCl and the Pt/C catalyst (20 wt% Pt) was synthesized by reduction of the dissolved Pt species using microwave assisted polyol route and ethylene glycol as the reducing agent. The process eliminates the steps necessary to recover the dissolved Pt in form of a Pt compound suitable for conventional Pt/C synthesis (e.g. H2PtCl6). The synthesized Pt/C was characterized for its structure and electrochemical performance. The study may be of interest for the PEMFC industry, which relies on the primary sources of Pt for their Pt/C electrocatalyst demand.