Sustainable Platinum Recycling through Electrochemical Dissolution of Platinum Nanoparticles from Fuel Cell Electrodes

Abstract

Recycling of the platinum group metals (PGMs) containing industrial wastes obtained from proton exchange membrane fuel cells (PEMFCs), electrolyzers, catalytic convertors and others is of high strategical importance for industrial sustainability. In this work, a highly efficient and environmentally friendly platinum recycling method through potentiodynamic cycling in dilute acidic chloride solutions is demonstrated and optimized to recover platinum from fuel cell electrodes. The process parameters such as upper and lower potential limits are optimized to be 1.6 and 0.4 V vs. RHE. Both the dilute acidic and the acid free Cl− containing electrolytes may be used for the dissolution. Moreover, parameters such as protocol reliability, quantification method and comparison, electrode interface structure, dissolution product and mechanisms etc. are discussed. A study in 1 M HCl shows Pt dissolution rates as high as ∼30 μg/cycle for potential cycling between 0.4 and 1.6 V (scan rate: 100 mV/s) for a PEMFC electrode with initial Pt loading of ∼470 μg. The approach demonstrates a methodology for fast parameter screening on electrocatalyst dissolution and a proof of concept industrial recycling of spent electrocatalysts.