Electrochemically Enhanced Oxygen Evolution and Urea Oxidation Reactions with Advanced High-Entropy LDH Nanoneedles

Abstract

This study describes the synthesis of innovative high-entropy layered double hydroxide (HE-LDH) nanoneedles, achieved through a straightforward hydrothermal method using a combination of cost-effective active non-nobel transition elements Fe, Co, Cr, Mn, Zn (denoted as FCCMZ) for electrocatalysis. The structure and elemental compositions of the synthesised HE-FCCMZ LDH were characterised by FE-SEM, FE-TEM, XRD, XPS, and ICP-OES. The electrocatalytic activity of oxygen evolution reaction (OER) and urea oxidation reaction (UOR) was analysed by LSV, CV, chronopotentiometry, and EIS methods. The resulting HE-FCCMZ LDH, exhibited superior performance in the electrocatalytic OER and UOR in alkaline medium. Specifically, the optimized HE-FCCMZ LDH sample demonstrated a low overpotential of 185 mV to achieve a current density of 10 mA/cm2, with a minimal Tafel slope of 87 mV/dec. It is superior to other ternary and quaternary elements LDHs. For the UOR, HE-FCCMZ LDH demonstrated very lower potential of 250 mV vs Hg/HgO. The HE-FCCMZ LDH demonstrated remarkable electrocatalytic OER performance, as evidenced by its high intrinsic activities, including the turnover frequency (TOF). Moreover, HE-FCCMZ LDH electrocatalysts showcased exceptional stability for 60 hours and it is potential for practical industrial use as OER catalysts