Superior electrochemical water oxidation in vacancy defect-rich 1.5 nm ultrathin trimetal-organic framework nanosheets

Engineering the 2D metal-organic framework (MOF) material can enrich the metal-unsaturated edges as active sites for catalysis, however, introducing multiple heterointerfaces and vacancy defects into 2D MOF and exploring their effects on electrocatalytic oxygen evolution reaction (OER) remain a major challenge. Here we construct ultrathin and highly curved 2D FeCoNi trimetal-organic framework nanosheets (FeCoNi-MOFs) with only approximately 1.5 nm thickness and abundant oxygen vacancies. The formed defect-rich FeCoNi-MOFs display outstanding OER performance with a much smaller overpotential of 254 mV at 10 mA cm-2 and remarkable stability for over 100 h in alkaline solutions. This is the highest OER activity level attained for directMOF catalysts. Theoretical analysis of FeCoNi MOFs with rich oxygen vacancies further suggests that the increased Fermi level with multiple heterointerfaces and the addition of oxygen vacancies co-facilitate the preoxidation of low-valence metals and the reconstruction/deprotonation of intermediate metal-OOH, thus enhancing electron transport efficiency.

Automated summary

This study successfully constructed ultrathin 2D FeCoNi trimetal-organic framework nanosheets with abundant oxygen vacancies, demonstrating outstanding performance in OER. The results suggest that multiple heterointerfaces and oxygen vacancies can significantly enhance catalytic activity.