Nickel and Nitrogen-Doped Bifunctional ORR and HER Electrocatalysts Derived from CO<inf>2</inf>

Abstract

While nonprecious metal catalysts (NPMCs) have been shown to be viable alternatives for Pt-based catalyst materials in both proton exchange membrane fuel cells (PEMFCs) and electrolyzers, all of the synthesis methods of these materials still have a positive carbon footprint. This means that, while the production of CO2 is avoided by converting to a hydrogen economy, a large amount of CO2 must be produced to drive this transition (as much as 600 kg of CO2 per kilogram of catalyst for CVD-based materials). Here, we demonstrate, for the first time, a sustainable method for synthesizing a bifunctional oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) catalyst directly from CO2 in a process that captures carbon dioxide from the atmosphere or flue gases instead of producing it as all previous methods for creating ORR/HER catalysts. The electocatalytic activity of the material is correlated to its structure and synthesis conditions by a thorough physicochemical analysis including rotating disk electrode (RDE) measurements, porosity analysis with N2 physisorption, scanning and transition electron microscopy imaging (SEM, TEM) and X-ray analysis of the materials' crystal structure and elemental composition. The material shows promising activity and paves way for a dual approach on reducing the CO2 footprint of the energy economy.