Efficient Bifunctional Electrocatalysts for Oxygen Evolution/Reduction Reactions in Two-Dimensional Metal–Organic Frameworks by a Constant Potential Method

The evolution of bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts that are highly active, stable, and conductive is crucial for advancing metal-air batteries and fuel cells. We have here thoroughly explored the OER and ORR performance for a category of two-dimensional (2D) metal-organic frameworks (MOFs) called TM₃(HADQ)₂, and Rh₃(HADQ)₂ exhibits a promising bifunctional OER/ORR activity, with an overpotential of 0.31 V for both OER and ORR. The d-band center (ε_d) and crystal orbital Hamilton populations (COHP) are utilized to study the relationship between OER/ORR activity and the electronic structure of catalysts, and it is found that the elementary d-electron number (Ne) of the central TM for TM₃(HADQ)₂, as well as the electronegativity of the ligand TM-N₄ and the intermediate O atom, are the main reason that affects the catalytic activity of OER/ORR. Additionally, Rh₃(HADQ)₂ can be proven through the constant potential method (CPM) and microkinetics method that it is an acidic OER/ORR bifunctional catalyst. Rh₃(HADQ)₂ has a high toxicity tolerance, making it a potential bifunctional catalyst. Our research contributes to both the rational design of SACs for various catalytic processes and the fabrication of bifunctional, cost-effective oxygen-electric catalysts.