Computational Insights into Two-Dimensional M₃(HHTP)₂ Metal–Organic Frameworks as ORR/OER Electrocatalysts

Advancements in energy conversion technologies critically depend on the development of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts that combine high activity, durability in acidic media, and cost-effectiveness. In this work, we employ first-principles calculations to investigate the mechanical strength, electrochemical stability, and catalytic performance of two-dimensional metal–organic frameworks (2D-MOFs), M3(HHTP)2, with M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene. Our results show that these frameworks possess notable mechanical robustness, exhibiting both high thermal stability and structural flexibility. Furthermore, the electrochemical stability of M3(HHTP)2 across the full pH range was analyzed using surface Pourbaix diagrams. The results indicate that only Mn3(HHTP)2, Zn3(HHTP)2, and Cu3(HHTP)2 are predicted to be unstable under acidic conditions. Regarding catalytic activity, frameworks with M = Mn, Ni, and Zn exhibit ORR overpotentials ranging from 0.42 to 0.46 V. Similarly, frameworks with M = Mn, Fe, Co, and Ni show OER overpotentials between 0.48 and 0.53 V. These values outperform those theoretically obtained for state-of-the-art commercial electrocatalysts such as Pt(111) for ORR and IrO2(110) for OER. Among the studied frameworks, Ni3(HHTP)2 emerges as the most promising bifunctional electrocatalyst, offering a compelling combination of low overpotentials and high electrochemical stability. These findings suggest the viability of 2D-MOFs as effective bifunctional electrocatalysts for advanced energy conversion processes.