ZIF-67 derived superhydrophilic Fe-CoP/Ni2P@NC to construct self-supported electrode for boosting electrochemical water splitting

Engineering interface, regulating morphology, and doping heteroatoms are regarded as effective strategies for boosting the electrocatalytic performances of transition-metal phosphides (TMPs), while still encounter some challenges to obtain desirable stability and sustaining catalytic activity. Herein, the Fe-CoP/Ni 2 P@NC/CC-350 self-supported electrode was successfully synthesized via pyrolysis of FeNi/ZIF-67/CC precursors followed by phosphating. In this structure, Fe-doped CoP and Ni 2 P composite nanoparticles are uniformly confined in the porous carbon matrix and anchored firmly on the surface of carbon cloth (CC). Moreover, the flocculent-like Fe-CoP/Ni 2 P@NC/CC-350 demonstrates superhydrophilicity to significantly facilitate mass transfer, while the unique morphology originates from a facile strategy of soaking ZIF-67/CC in the mixed solution composed of FeSO 4 and NiSO 4 . The synthesized Fe-CoP/Ni 2 P@NC/CC-350 integrates the advantages of abundant active sites, confinement effect, interface regulation and superhydrophilicity, thereby demonstrating superior HER and OER activities and stabilities in an alkaline medium (1.0 M KOH). Remarkably, Fe-CoP/Ni 2 P@NC/CC-350 electrodes used both as anode and cathode require a cell voltage of only 1.49 V at 10 mA cm −2 , much lower than that of the well-established 20 % Pt-C/CC and RuO 2 /CC couple (1.612 V). Besides, Fe-CoP/Ni 2 P@NC/CC-350 Fe-CoP/Ni 2 P@NC/CC-350 system exhibits an outstanding stability for monitoring water splitting up to 100 h at 10 mA cm −2 . DFT results further confirm that the heterointerface and Fe doping in Fe-CoP/Ni 2 P@NC/CC-350 lead to a upshift d-band center of active sites and decreased reaction Gibbs energy barrier for the rate-determining step during catalysis, thereby contributing to the superior HER and OER activities. The work provides a novel strategy to construct a superhydrophilic microstructure, and the synergistic effect of electrons originating from the heterointerface and doping paves the way for designing electrocatalysts with high activities toward water splitting.