Cerium and iron co-doped ZIF-8 as an efficient bifunctional electrocatalyst for water splitting

Developing high-efficiency, low-cost, and stable bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential for the large-scale industrialization of green hydrogen production. In this work, a novel Ce and Fe co-doped ZIF-8 electrocatalyst (Ce,Fe-ZIF-8) was successfully synthesized through a facile room-temperature ion-exchange strategy. The as-prepared catalyst retains the characteristic rhombic dodecahedral morphology of the ZIF-8 framework with a refined particle size of ∼86 nm and highly dispersed active sites. Benefiting from the synergistic electronic modulation between the rare-earth Ce and the transition metal Fe, Ce,Fe-ZIF-8 demonstrates outstanding bifunctional activity in 1.0 mol/L KOH electrolyte. Specifically, it requires overpotentials of only 242 mV (OER) and 96 mV (HER) at 10 mA/cm 2 . When utilized as both the anode and cathode for overall water splitting, the Ce,Fe-ZIF-8||Ce,Fe-ZIF-8 system achieves a current density of 10 mA/cm 2 at a remarkably low cell voltage of 1.58 V, surpassing the performance of commercial Pt/C||RuO 2 . Furthermore, the catalyst exhibits robust electrochemical stability for over 200 h of continuous operation. This work provides a facile and effective strategy for designing high-performance metal-organic framework (MOF)-based bimetallic electrocatalysts for sustainable energy conversion applications.