Improving the Electrocatalytic Activity of a Core/Shell NiCo–ZIF@PBA Catalyst by Co–O–Fe Bridge Bonds for Water Oxidation

Abstract

In response to the limitations of slow reaction kinetics and elevated overpotentials in the OER, a novel core–shell structured electrocatalyst, termed NiCo–ZIF-67@Fe–Co–Ni-PBA or NiCo–ZIF@PBA, has been developed. This material demonstrates exceptional catalytic performance, exhibiting a minimal overpotential of approximately 188 mV at 10 mA cm^–2, alongside a Tafel slope of 109 mV dec^–1. Its robust stability in a 1 M KOH solution during the OER operations is noteworthy. Theoretical insights from DFT calculations reveal that a Co–O–Fe bridging configuration within NiCo–ZIF@PBA lowers the energy barrier for the reaction to 1.79 eV, a significant reduction from 2.67 eV observed with NiCo–ZIF-67. The improvement in electrochemical performance is primarily due to the emergence of Co³⁺ ions, which results from the efficient charge transfer occurring at the interface of the PBA and NiCo–ZIF core–shell structure. These findings suggest a promising strategy for designing advanced core–shell materials for electrocatalytic applications.