Teppor, P.; Jager, R.; Koppel, M.; Volobujeva, O.; Palm, R.; Mansson, M.; Härk, E.; Kochovski, Z.; Aruvali, J.; Kooser, K.; Granroth, S.; Kaambre, T.; Nerut, J.; Lust, E.: Unlocking the porosity of Fe-N-C catalysts using hydroxyapatite as a hard template en route to eco-friendly high-performance AEMFCs. Journal of Power Sources 591 (2024), p. 233816/1-11
10.1016/j.jpowsour.2023.233816
Abstract:
In this work, we propose hydroxyapatite (HA) as a hard template to unlock the porosity of Fe–N–C catalyst materials. Using HA, a naturally occurring mineral that can be removed with nitric acid, in the synthesis generates a catalyst material with a unique porous network comprising abundant pores and interparticle cavities ranging from 10 to 3000 nm. Hard templating with HA alongside ZnCl2 as a micropore former results in a Fe–N–C catalyst based on naturally abundant peat with excellent oxygen reduction activity in alkaline conditions. A half-wave potential of 0.87 V vs RHE and a peak power density of 1.06 W cm 2 were achieved in rotating ring disk electrode and anion exchange membrane fuel cell experiments, respectively, rivaling the performance of other state-of-the-art platinum-free catalysts presented in the literature. A combined approach of using renewable peat as a carbon source and HA as a hard template offers an environmentally friendly approach to high-performance Fe–N–C catalysts with abundant porosity.