Construction of Local Electron-Rich Active Centers in High-Entropy Alloys via a Self-Reduction Way for Efficient Water Oxidation

Abstract

High-Entropy Alloys (HEAs) consisting of five or more elements in high concentrations have gained popularity as an ideal platform for catalysts due to their unique chemical properties and physical structure. However, facile synthesis methods are needed to overcome the high energy consumption and stringent requirements of traditional HEAs fabrication. In this work, we designed a quinary FeCoNiVMo HEAs catalyst, obtained through a one-step hydrothermal and self-reduction treatment. The catalyst exhibits excellent OER performance with a 289 mV overpotential to achieve 10 mA·cm^–2 in an alkaline medium and remarkable stability over 2000 min. The characterization results show that the introduction of both V and Mo greatly improves the electronic modulation among complex chemical compositions and optimizes electron transfer during OER. The DFT analysis revealed that the active center received a greater influx of electrons due to the chemical interactions among the five metals, resulting in the formation of an electron-rich zone. The electron-rich zone could produce more efficient active centers, and the polymetallic model enabled a stronger electron-accepting capability at the active sites. This was beneficial for enhancing the free-energy optimization of intermediate adsorption, thereby boosting the inherent catalytic activity. This work provides a facile synthesis of high-entropy alloys using a formic acid ligand as a sacrificial reductant, and a reference worthy idea of the catalytic mechanism of HEAs, which provides favorable support for the future development of a variety of low-cost transition metal catalysts.