Efficient oxygen evolution catalysts with synergistic reactivity: CoFe2O4/C derived from bimetallic organic framework supported on nitrogen-doped carbon nanoarray structure.

CP@NC-CoFe 2 O 4 /C as catalysts for OER: we covered a polyaniline nanowire array on carbon paper by a electrochemical polymerization method, directly grown MOF-74-Co/Fe on its surface and pyrolyzed to form the CoFe 2 O 4 /C supported on nitrogen-doped carbon nanoarray meterial, which is prepared a highly active and stable OER catalyst. High specific surface area, high utilization of the catalyst, enhanced electron transport characteristics and retention characteristics of the original carbon paper characteristics ensure excellent OER activity. Our results show great promise for developing OER catalysts as precious metal substitutes for PANI and MOFs complexes through a low-cost, scalable method. [Display omitted] • Polyaniline nanowire array was covered on carbon paper, directly grown MOF-74-Co/Fe on its surface. • The presence of PANI nanowire arrays also retains the original properties of carbon paper. • The unique 3D nano-array structure enhance the OER catalytic efficiency. • DFT reveals the main surface adsorbent is OH*, and surface Co atoms are the main active sites. Here, we covered a polyaniline nanowire array (denoted as PANI) on carbon paper (denoted as CP) by a electrochemical polymerization method, directly grown MOF-74-Co/Fe on its surface and pyrolyzed to form the CoFe 2 O 4 /C supported on nitrogen-doped carbon nanoarray materials (denoted as NC-CoFe 2 O 4 /C@CP), which is prepared a highly active and stable OER catalyst. PANI can not only be used as a "binder", grow MOF on its surface and cover the carbon paper, but also improve the conductivity and stability of the material by forming nitrogen-doped carbon after pyrolysis. And its unique 3D nano-array structure not only greatly increases the surface area, but also provides more attachment sites for CoFe 2 O 4 , thereby accelerating electron transport and improving OER performance. High specific surface area, high utilization of the catalyst, enhanced electron transport characteristics and retention characteristics of the original carbon paper characteristics ensure excellent OER activity. The final sample exhibits outstanding activity for OER in alkaline solution, accompanied by a low onset potential about 1.52 V (vs reversible hydrogen electrode), and the small Tafel slope of 70 mV dec−1. In particular, after 21600s, the current drop is negligible, which is means that the NC-CoFe 2 O 4 /C@CP catalyst has the high stability. Density Functional Theory (DFT) calculation reveals the main surface adsorbent of CoFe 2 O 4 is OH*, and the surface Co atoms are the main active sites. [ABSTRACT FROM AUTHOR]