Petal-like high-entropy metal-organic framework grown on nickel foam as a bifunctional electrocatalyst for efficient...

The rapid advancement of global industrialization in the 21st century has exacerbated energy crises and environmental degradation, driving an urgent demand for efficient, renewable, and sustainable energy technologies. High-entropy metal-organic frameworks (HE-MOFs), owing to their structural diversity and tunability, have emerged as promising electrocatalytic materials. In this study, a series of metal-organic frameworks were synthesized via hydrothermal methods using 4,4'-dihydroxy-3,3'-biphenyldicarboxylic acid (H₄DOBPDC) as the organic linker. The resulting HE-DOBPDC material, featuring a unique petal-like morphology, demonstrated excellent catalytic activities for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). As a bifunctional catalyst for overall water splitting, HE-DOBPDC achieved a current density of 10 mA cm^-2 at a low applied voltage of 1.56 V and maintained stable performance over 120 h without significant degradation. Comprehensive analyses using Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and in-situ Raman spectroscopy revealed that the formation of Fe-OOH, Ni-OOH and Co-OOH intermediates during electrolysis likely contributed to its superior catalytic performance. This work offers valuable insights for designing cost-effective, highly-performance active catalytic materials for water electrolysis applications.