CO2 transformed into highly active catalysts for the oxygen reduction reaction via low-temperature molten salt electrolysis

Abstract

The implementation of a technology capable of capturing and converting CO₂ into valuable products is one of the key requirements for limiting the effects of our carbon-intensive industries. At the same time, future CO₂ emissions need to be reduced to combat climate change, meaning that new devices capable of storing and converting energy without CO₂ emissions have to be adopted widely. In this work, we demonstrate catalysts made directly from CO₂ for fuel cells and zinc-air batteries. The molten salt electrolysis process is used to electrodeposit solid carbon from CO₂ in two mixtures, a known eutectic mixture of Li₂CO₃, Na₂CO₃, K₂CO₃ and a new mixture containing 0.1 mol of LiOH in addition. The effects of the electrolyte towards the final carbon product and its electrocatalytic activity are analysed using the rotating disk electrode method, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The porosity of the materials is described by N₂ adsorption and the best performing catalyst is compared to the activity of a commercial 20 wt% PtRu/C material in a zinc-air battery.