Construction of 2D CoFe-MOF derived from LDH electrocatalyst for efficient oxygen and urea evolution.

Abstract

Two-dimensional metal-organic framework (2D MOF) materials have significant development prospects in the technology of urea-assisted water electrolysis for hydrogen production. However, the poor conductivity, low mass permeability, and stability have limited their development in electrocatalysis. Here, CoFe-BDC is synthesized using layered double hydroxides (LDH) as the template. The effect of different ligands of CoFe-MOF on the microstructure and electrocatalytic performance is systematically investigated. Terephthalic acid has the weakest destructive ability and strongest coordination ability due to its high symmetry in spatial structure and its weakest acidity than other ligands, leading to the production of massive active sites. CoFe-BDC has the best electrocatalytic activity (oxygen evolution reaction (OER): η₁₀₀ = 258 mV, urea oxidation reaction (UOR): η₁₀₀ = 1.34 V, overall water splitting (OWS): E₁₀₀ = 1.76 V). CoFe-BDC is observed to undergo a catalytic transformation to FeOOH at a reconstruction voltage of 1.4 V via in situ Fourier transform infrared spectroscopy and Raman spectroscopy. This study provides a new approach of 2D MOFs materials using template method for water electrolysis.