N–V2O5@FeC from spongy V2O5 composite and Fe-intercalated graphitic nitrogen for electrocatalytic oxygen evolution reaction

Four-electron transfer process of oxygen evolution reaction (OER) has become a bottleneck restricting water electrolysis, due to its inherently high kinetic energy barrier. Therefore, the exploration for high-efficiency and long-term stable non-noble metal OER catalysts is crucial for sustainable energy conversion. This work designs a molten salt-mediated ball milling-pyrolysis stepwise treatment to synthesize spongy V 2 O 5 composite Fe-intercalated graphitic nitrogen (N–V 2 O 5 @FeC). Specifically, Fe-intercalated graphite is achieved using the FeCl 3 /KCl molten salt system, a highly conductive FeC substrate being constructed accordingly. Then, NH 3 generated from melamine pyrolysis enables spongy porous structure construction and N-doping. N–V 2 O 5 @FeC catalyst possesss the following advantages: First, spongy porous structure greatly increases exposure of active sites, while Fe intercalation-induced graphite edge defects and Fe–O–V bonds jointly enhance active site density of V 2 O 5 composite, thereby boosting catalyst activity. Second, N-doped carbon network improves electron transport performance, enabling catalyst's charge transfer resistance decline to 19.9 Ω. Moreover, dual stabilization mechanisms of Fe–O–V stable structure and chemical anchoring of V–O–C bonds endow the material with good structural stability under alkaline conditions. In detail, N–V 2 O 5 @FeC reaches 10 mA cm −2 current density at only 299 mV overpotential in alkaline solution, with low Tafel slope (53.0 mV dec −1 ) and 50-h stability.