In situ assembly of the FeOOH@MOF-74 heterostructure on IF as efficient electrocatalysts for water splitting

Abstract

The development of cost-effective and highly efficient electrocatalysts for oxygen and hydrogen production is essential for realizing sustainable hydrogen energy. In this study, a nano-heterostructure composed of a metal–organic framework (MOF) and iron oxyhydroxide (FeOOH) deposited on iron foam (FeOOH@MOF-74/IF) was designed using a two-step method. The synergistic combination of FeOOH and MOF-74 in the FeOOH@MOF-74/IF heterostructure facilitates strong electronic interactions and efficient charge transfer, leading to outstanding electrocatalytic activity for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The material requires overpotentials of only 188 mV and 157 mV to achieve a current density of 10 mA cm⁻² for the OER and HER, respectively, in 1 M KOH electrolyte. Moreover, when utilized as both the cathode and anode in a water-splitting cell, it delivers a current density of 100 mA cm⁻² at a low cell voltage of 1.50 V. Density functional theory (DFT) calculations reveal that the heterostructure reduces the OER energy barrier and enhances conductivity and charge transport efficiency. The strengthened Ni and *O interaction in FeOOH@MOF-74/IF alters the rate-determining step (RDS), further improving catalytic performance. The successful implementation of this iron-rich electrode in overall water splitting highlights its potential as a cost-effective, high-performance electrocatalyst for clean hydrogen generation.