Synergistic Effects of PtRhNiFeCu High Entropy Alloy Nanocatalyst for Hydrogen Evolution and Oxygen Reduction Reactions

The unique properties of high entropy alloy (HEA) catalysts, particularly their severe lattice distortion and the synergistic effect of multiple components, endow them with exceptional multifunctional catalytic performance. Herein, it is revealed for the first time, that the ultrasmall PtRhNiFeCu HEA nanoparticles catalyst shows outstanding catalytic activity for both hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). The catalyst exhibits an impressively low overpotential of 13 mV at 10 mA cm-2, a Tafel slope of 29.6 mV dec-1, and high mass activity of 7.6 A mgPt-1 at -50 mV in alkaline media, and long-term stability of at least 20 h. Moreover, the catalyst also demonstrates effective catalytic activity for acidic ORR with a commendable performance of 1.23 A mgPt-1, much exceeding the commercial Pt/C catalyst. Density functional theory (DFT) calculations unveil that the efficient electrocatalytic performance for HER and ORR can be primarily attributed to the synergistic effect between components tailors and optimizes the electronic structure of PtRhNiFeCu/C HEA, which not only enhances the HER activity through increasing water capture capability, decreasing energetic barrier for water dissociation, and optimizing hydrogen absorption but also initiates non-platinum active sites with high ORR activity, achieving the improved ORR performance. Under the synergistic effect of up to five atoms, the surface electronic structure and coordination environment of ultrasmall high entropy alloy PtRhNiFeCu nanoparticles are optimized, exhibiting high oxygen reduction and hydrogen evolution reaction performance in acidic and alkaline environments, respectively.image