Owing to their strong catalytic nature and high robustness under various conditions, platinum group metals (PGMs) are state-of-the-art electrocatalysts for proton exchange membrane fuel cells and electrolyzer cells (PEMFCs & ECs) of superior performance and long stability. However, PGM supplies involving limited natural reserves, energy intensive mining process and related environment issues raise increasing concerns. As an indispensable (though insufficiently developed) aspect of the PEM technologies, sustainable PGM recovery and reuse can fundamentally tackle those concerns and serve as a strong support to further secure widespread commercialization of the technologies.

Due to the popular use of perfluorinated sulfonic acid as proton conduction component, PGMs in PEMFCs&ECs are not suitable for recycling through the traditional pyrometallurgical route, which operates at a temperature over 1500°C. Burning of the electrodes releases huge amount of emission, which is not only harmful to the environment and human, but also corrosive to the process infrastructure.

An alternative PGM recycling process using a hydro-electrochemical route^{1, 2} reveals many advantages, including high extraction efficiency, environmental friendliness, recovery of multiple components, low demand for operation conditions & maintenance, etc. Adopting the intrinsic degradation mechanisms of the PGM nanoparticles in combination with surface potential modulation, dissolution behavior of typical PEMFC&EC electrocatalysts have been systematically investigated. Under optimal parameters, a recovery efficiency of over 99% was successfully achieved for platinum electrocatalyst. Moreover, new catalysts prepared from the recycled precursor demonstrated competitiveness to that of commercial equivalents.

In project 3R, as a joint effort of fuel cell industries, recycling companies and academics supported by Danish Energy Agency, the achievements document a valuable milestone towards truly renewable and green energy conversion technologies.

Acknowledgment

Financial support from Danish Energy Agency EUDP project 3R, Nr. 64019-0551; Innovation Fund Denmark, InnoExplorer program, Nr. 9122-00112; Danish ESS lighthouse on hard materials in 3D, SOLID, Grant number 8144-00002B; Energi Fyns Udviklingsfond.

Corresponding author

Shuang Ma Andersen: mashu@igt.sdu.dk

Reference

1. Sharma, R.; Gyergyek, S.; Andersen, S. M. ChemSusChem 2018, 11, (21), 3742-3750.
2. Sharma, R.; Rode Nielsen, K.; Brilner Lund, P.; Bredmose Simonsen, S.; Grahl-Madsen, L.; Ma Andersen, S. ChemElectroChem 2019, 6, (17), 4471-4482.