Hetero-Polyatomic Phosphorous Anion-Based High-Entropy Electrocatalyst for Efficient Bifunctional Water Electrolysis in Anion Exchange Membrane Water Electrolyzers

High-entropy materials represent a highly promising platform for electrocatalysis, offering exceptional stability and activity due to their multiple active sites and stabilization by high-entropy, suitable for green hydrogen production via alkaline water electrolysis. Nonetheless, current challenges, such as limited miscibility among metal cations, restrict the advancement of high-entropy materials through the maximization of the high-entropy effect, highlighting the need for further research into the practical implementation of high-entropy electrocatalysts. In this study, we propose and synthesize a nonprecious high-entropy material composed of Co, Fe, Ni, Mo, Ti, and hetero-polyatomic phosphorous anions (H-PPAs) as a new family of H-PPAs-based electrocatalyst platform for efficient alkaline water splitting via electrodeposition. The amorphous structure of the material, reinforced by high configurational entropy and H-PPA groups, not only remains stable but also promotes enhanced synergistic effects among metal cations, hence effectively modulating both the morphology and electronic structure of the active sites. This high-entropy H-PPAs-based electrocatalyst achieves low overpotentials of 37 and 226 mV at a current density of 10 mA cm⁻² for the hydrogen evolution reaction and oxygen evolution reaction, respectively, in alkaline electrolytes. Moreover, an anion exchange membrane water electrolyzer (AEMWE) employing the high-entropy H-PPAs-based catalyst as bifunctional anode and cathode electrocatalysts operates at only 1.80 V to deliver a practically high current density of 1 A cm⁻², sustaining its performance for over 100 h and demonstrating the strong potential of high-entropy materials in energy conversion applications.