Efficient Bifunctional Electrocatalysts for Oxygen Reduction/Evolution Reactions in Two-Dimensional Diamine-Based Metal−Organic Frameworks

Abstract

Developing high-performance bifunctional electrocatalysts for the oxygen reduction/evolution reaction (ORR/OER) is crucial for solving environmental and energy challenges. Herein, we systematically investigate the geometric structures, stability, electronic properties, and ORR/OER performance of a series of two-dimensional (2D) metal−organic frameworks (MOFs), called TM3(HITT)2 (TM = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt), by means of density functional theory (DFT) calculations. The computational results indicate that all proposed frameworks possess excellent structural stability and potential experimental feasibility, as evidenced by cohesive energy, formation energy, and ab initio molecular dynamics (AIMD) simulations. Among all candidates, Fe3(HITT)2 and Rh3(HITT)2 exhibit excellent bifunctional catalytic activity with relatively low overpotentials for both ORR and OER, and their catalytic performances are comparable to those of well-studied ORR and OER electrocatalysts. Scaling-relation and volcano-plot analyses reveal that the catalytic activity is closely associated with the adsorption strength of oxygen-containing intermediates, and that an appropriate balance between intermediate adsorption and desorption is essential for achieving efficient bifunctional catalysis. This work not only identifies Fe3(HITT)2 and Rh3(HITT)2 as promising bifunctional ORR/OER electrocatalysts but also provides valuable theoretical insights for the rational design of advanced 2D MOF-based catalytic materials.