High entropy rare-earth Prussian blue analogues for boosting oxygen evolution catalysis

The development of high-performance, stable, and cost-effective catalysts is crucial for advancing the oxygen evolution reaction (OER) in alkaline environments. In this study, we report the successful introduction of high-entropy technology into metal-organic frameworks using a facile and tunable one-step room-temperature co-precipitation method to enhance the OER performance. The X-ray photoelectron spectroscopy (XPS) and elemental mapping data indicated the successful incorporation of the metal elements into the metal-organic frameworks. Additionally, the synthesized high-entropy porous coordination polymers (PBAs) exhibited a cubic-like crystal structure. NiFeLaMoCo-PBA showed exceptional electrocatalytic water splitting performance in an alkaline environment, with an overpotential of only 244 mV at a current density of 10 mA cm^-2 and a Tafel slope of merely 32 mV dec^-1. The stability of 48 h was achieved in 1 M KOH solution with a current density of 50 mA cm^-2. The enhanced OER activity and stability of the NiFeLaMoCo-PBA catalyst compared to NiCo-PBA systems primarily stems from the strategic incorporation of Fe, La, and Mo elements into the high-entropy Prussian blue analog architecture. This multielement integration not only optimizes electron transport kinetics but also establishes a robust multimetallic synergistic framework. The resultant electronic structural modulation facilitates charge transfer processes while the coordinated interactions among the five metallic components synergistically lower the activation energy barrier, thereby enhancing the OER performance of the catalyst in alkaline media. The current study demonstrates that NiFeLaMoCo-PBA is a promising candidate for an efficient and cost-effective OER electrocatalyst.