Tunable Syngas Formation at Industrially Relevant Current Densities via CO₂Electroreduction and Hydrogen Evolution over Ni and Fe‐derived Catalysts obtained via One‐Step Pyrolysis of Polybenzoxazine Based Composites

Abstract Simultaneous electroreduction of CO₂and H₂O to syngas can provide a sustainable feed for established processes used to synthesize carbon‐based chemicals. The synthesis of MO_x/M‐N‐Cs (M = Ni, Fe) electrocatalysts reported via one‐step pyrolysis that shows increased performance during syngas electrosynthesis at high current densities with adaptable H₂/CO ratios, e.g., for the Fischer–Tropsch process. When embedded in gas diffusion electrodes (GDEs) with optimized hydrophobicity, the NiO_x/Ni‐N‐C catalyst produces syngas (H₂/CO = 0.67) at −200 mA cm⁻²while for the FeO_x/Fe‐N‐C syngas production occurs at ≈−150 mA cm⁻². By tuning the electrocatalyst's microenvironment, stable operation for >3 h at −200 mA cm⁻²is achieved with the NiO_x/Ni‐N‐C GDE. Post‐electrolysis characterization revealed that the restructuring of the catalyst via reduction of NiO_xto metallic Ni NPs still enables stable operation of the electrode at −200 mA cm⁻², when embedded in an optimized microenvironment. The ionomer and additives used in the catalyst layer are important for the observed stable operation. Operando Raman measurements confirm the presence of NiO_xduring CO formation and indicate weak adsorption of CO on the catalyst surface.