Medium-Entropy Engineering of Pt/FeCo Layered Double Hydroxide for Synergistically Enhanced Alkaline Hydrogen Evolution

Developing efficient, stable, low-platinum (Pt)-loading electrocatalysts for the hydrogen evolution reaction (HER) is key for advancements in green hydrogen technology. In this work, a "medium-entropy engineering" strategy was introduced simply by a two-step hydrothermal method. Then a low-loading Pt/FeCo layered double hydroxide (LDH) medium-entropy hybrid (MEH) electrocatalyst was constructed on nickel foam. Systematic characterization shows that this approach affords the dispersion of Pt nanoparticles onto a three-dimensional flower-like nanostructure and plentiful surface defects. X-ray photoelectron spectroscopy (XPS) analysis shows strong electron interaction between Pt and the FeCo LDH support and cooperatively tunes the electronic structure as a consequence. In 1 M KOH electrolyte, Pt/FeCo LDH-MEH-0.02 exhibits excellent HER activity with overpotentials of only 19 mV and 64 mV to deliver current densities of 10 mA cm^-2 and 100 mA cm^-2 respectively to outperform commercial Pt/C and a series of control samples. Furthermore, its Tafel slope is low at 30.1 mV dec^-1, has a significantly lowered charge-transfer resistance and long-term excellent operation stability. Our study reports a design strategy for preparing high-performance, low-Pt-loading electrocatalysts through medium-entropy engineering.