Novel high-entropy layered double hydroxide microspheres as an effective and durable electrocatalyst for oxygen evolution

Abstract

In this work, novel high-entropy layered double hydroxide (HELDH) microspheres consisting of nanosheets were synthesized via a simple hydrothermal method through utilizing the combination of low-cost active transition metal elements such as Ni, Fe, Mn, Zn, and Co, as well as non-active Mg and Al elements for electrocatalysis. The reported flower-like seven-element HELDH microspheres self-supported on a nickel foam substrate outperformed the hydroxide analogues with a similar structure in the electrocatalytic oxygen evolution reaction. Specifically, the optimal sample only requires a low overpotential of 183 mV to obtain a current density of 10 mA cm⁻² with a small Tafel slope of 49.21 mV dec⁻¹ (more active than RuO₂ electrocatalysts) and has an outstanding cycling stability. Furthermore, in 1.0 mol L⁻¹ KOH solution, the potential shows only a negligible increase (<5%) after a continuous test of 48 h even at a high current density of 250 mA cm⁻², suggesting its robust durability and promising potential for practical industrial application as OER catalysts. Thus, the present work provided a new strategy to design and prepare high-performance HEM electrocatalysts. In addition, the theoretically calculated results based on density functional theory with the proposed models completely support our experimental results, which provide a new way to manipulate the catalytic performance of HEM electrocatalysts.