Metal doping and Hetero-engineering of Cu-doped CoFe/Co embedded in N-doped carbon for improving trifunctional electrocatalytic activity in alkaline seawater

Using Cu-CoFe/Co/NC as trifunctional electrocatalysts in alkaline seawater, an overall hydrazine splitting (OHzS) unit is self-powered by a direct hydrazine fuel cell (DHzFC), demonstrating the great potential of Cu-CoFe/Co/NC as trifunctional electrocatalysts toward energy storage and conversion devices. • Cu-doped CoFe/Co encapsulated by N-doped carbon (Cu-CoFe/Co/NC) is synthesized. • The electronic structure and d-band center of catalyst are regulated. • The catalyst show good ORR, HzOR and HER performance in alkaline seawater. • The catalyst is used into direct hydrazine fuel cell and overall hydrazine splitting. The development of high-performance and robust electrocatalyst suitable for oxygen reduction reaction (ORR), hydrazine oxidation reaction (HzOR), and hydrogen evolution reaction (HER) in seawater still faces huge challenges. In this study, Cu-doped CoFe/Co encapsulated by N-doped carbon (Cu-CoFe/Co/NC) is synthesized via chemical precipitation followed by carbonization method, in which the electronic structure and d-band center of Cu-CoFe/Co/NC are regulated by metal doping and hetero-engineering. The as-synthesized Cu-CoFe/Co/NC exhibit excellent electrocatalytic activity for ORR ( E 1/2 = 0.87 V), HzOR ( η 10 = 281 mV), and HER ( η -10 = 217 mV) in alkaline seawater. Inspiringly, the self-assembled direct hydrazine fuel cell (DHzFC) are used to power overall hydrazine splitting (OHzS) for proof of concept, demonstrating the great potential of Cu-CoFe/Co/NC as trifunctional electrocatalyst toward energy storage and conversion devices.