Oxygen vacancy modulation in interfacial engineering FeO over carbon nanofiber boosting ambient electrocatalytic N reduction.

The oxygen vacancy modulation of interface-engineered FeO nanograins over carbon nanofiber (Fe@CNF) was achieved to improve electrocatalytic nitrogen reduction reaction (NRR) activity and stability via facile electrospinning and tuning thermal procedure. The optimal catalyst calcined at 800 ℃ (Fe@CNF-800) was endowed with abundant nanograin boundaries and optimized oxygen vacancy (V) concentration of iron oxides, thereby affording 37.1 μg h mg (-0.2 V vs. reversible hydrogen electrode (RHE)) NH yield and rational Faraday efficiency (10.2%), with 13.6 times atomic activity enhancement compared to of that commercial FeO. The interfacial effect of assembled nanograins in particles correlated with the formation of V and more intrinsic active sites, which is conducive to the trapping and activation of nitrogen (N). The in-situ X-ray photoelectron spectroscopy (XPS) measurement revealed the real consumption of adsorbed oxygen when introducing N by the trapping effect of V. Density-Functional-Theory (DFT) calculation validates the promotive hydrogenation effect and elimination of hydrogen intermediate (H*) interacted with N transferring toward oxygen of the support. The optimal catalyst shows a lasting NRR activity at least 90 h, outperforming most reported Fe-based NRR catalysts.