Unconventional Interconnected High-Entropy Alloy Nanodendrites for Remarkably Efficient C−C Bond Cleavage toward Complete Ethanol Oxidation

Abstract

Developing ethanol oxidation electrocatalysts with high catalytic activity, durability, and resistance to CO poisoning remains a major challenge. In recent years, high-entropy alloys (HEAs) with unique physical and chemical properties have garnered substantial attention. Herein, a class of HEA nanodendrites are designed by a simple wet-chemical method. The mass activity and specific activity of the septenary PtIrRhCoFeNiCu high-entropy alloy catalyst are 2.13 A mg_Pt⁻¹/1.05 A mg_Pt+Ir+Rh⁻¹ and 2.95 mA cm⁻², which reach 5.76-/2.84-fold and 5.57-fold improvements relative to commercial Pt/C (0.37 A mg_Pt⁻¹ and 0.53 mA cm⁻²), respectively. Remarkably, after the i-t test of up to 100,000 s and the accelerated durability test of 1500 cycles, 81.22 % and 68.54 % of the initial mass activity are well retained, respectively. The lattice distortion-associated local tensile strain as demonstrated by increased Pt−Pt bond length enhances ethanol adsorption and reduces reaction barriers. Moreover, hysteresis diffusion effect induced by lattice distortion in the HEA nanodendrites contributes to their superb ethanol oxidation stability. In situ infrared absorption spectroscopy reveals that the three HEA nanodendrites mainly follow C1 pathway with C−C bond breaking to form CO followed by CO oxidation especially at a wide range of high potentials. Theoretical calculations reveal that among these HEAs, PtIrRhCoFeNiCu possesses the lowest energy barrier for C−C bond scission due to synergy among Pt/Ir/Rh and water dissociation due to synergy among Co/Fe/Ni/Cu. This work provides insights to design unique HEA nanostructures with extraordinary catalytic performances and selectivity compared to conventional nanoparticles.