CO2 Turned into a Nitrogen Doped Carbon Catalyst for the Fuel Cell and Metal-Air Battery Applications

Abstract

Metal-free catalysts based on nitrogen-doped carbon are among the most promising replacements for Pt-based materials on polymer electrolyte membrane fuel cell (PEMFC) cathodes due to their inherent stability (lack of metal atoms bypasses most of the degradation mechanisms encountered in metal-based non-precious metal catalysts). However, the production of carbon nanostructures that have suitable oxygen reduction reaction (ORR) activities for fuel cell cathode use can create massive amounts of CO2 as a by-product, which counteracts the environmental friendliness of fuel cells. Here, we demonstrate a new method for creating ORR catalysts directly from CO2, which can produce a catalyst with a negative carbon footprint instead of a positive one. Via a fused Li-K carbonate eutectic mixture or pure Li2CO3, CO2 was split into gaseous oxygen and solid carbon, which was then doped with nitrogen using a pyrolysis process with the presence of dicyandiamide and polyvinylpyrrolidone. A thorough physico-chemical characterization of the catalyst materials is presented alongside their electrocatalytic properties for the ORR. The reasons for the properties of the resulting carbon depending on the electrolyte mixture for CO2 electrolysis and deposition temperature are explored. The best performing material had ORR activity nearing that of Pt/C, showing the potential that this method has for creating competitive catalysts while remaining environmentally benign [1]. References Ratso, S.; Walke, P. R.; Mikli, V.; Ločs, J.; Šmits, K.; Vītola, V.; Šutka, A.; Kruusenberg, I. CO2 Turned into a Nitrogen Doped Carbon Catalyst for Fuel Cells and Metal–Air Battery Applications. Green Chem. 2021, 23 (12), 4435–4445. https://doi.org/10.1039/D1GC00659B. Figure 1