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

Simultaneous electroreduction of CO and HO to syngas can provide a sustainable feed for established processes used to synthesize carbon-based chemicals. The synthesis of MO/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 H/CO ratios, e.g., for the Fischer-Tropsch process. When embedded in gas diffusion electrodes (GDEs) with optimized hydrophobicity, the NiO/Ni-N-C catalyst produces syngas (H/CO = 0.67) at -200 mA cm while for the FeO/Fe-N-C syngas production occurs at ≈-150 mA cm. By tuning the electrocatalyst's microenvironment, stable operation for >3 h at -200 mA cm is achieved with the NiO/Ni-N-C GDE. Post-electrolysis characterization revealed that the restructuring of the catalyst via reduction of NiO to metallic Ni NPs still enables stable operation of the electrode at -200 mA cm, 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 during CO formation and indicate weak adsorption of CO on the catalyst surface.