Unraveling the Operando Structural and Chemical Stability of Rare-Earth Substituted Ceo2 Electrocatalysts for Oxygen Evolution Reactions

Abstract

Highly efficient, abundant, and long-lasting electrocatalysts for oxygen evolution will be a key step toward industrial hydrogen production via water splitting. Recently, in water electrolyzers, co-doped metal oxides are employed to reduce energy loss during electrochemical oxygen evolution reactions (OER), a great alternative to noble-metal derived materials. In the present work, Nd-dopped CeO2 (CeNdO2) nanostructures (Ns) co-doped with rare earth metals (REMs) are synthesized via sol-gel technique and are analyzed through different analytical techniques with a focus on structural, morphological, elemental, electrical as well as electronic properties. All the synthesized samples were coated on nickel foam (NF) and fluorinated tin oxide (FTO) substrate for electrochemical water splitting in a 1.0 M KOH solution. The Pr/Nd co-doped CeO2 grown on NF demonstrates high electrochemical activity with a greatly reduced OER overpotential of 274 mV, Tafel slope of 84 mV/dec, and increases electrochemical surface area. This co-doped metal oxide nanostructure causes interactions with oxy-radicals (confirmed from XPS and Raman) are thought to be the source of easy charge transport and decrease in overpotential. The least charge transfer resistance of Pr-doped CeNdO2/NF presented excellent electroactive nature due to reduced polarization resistance between electrolyte and catalyst material. Additionally, for a practical water electrolysis system, the high stability of Pr doped CeNdO2/NF electrode was getting exposed by continuous cyclic voltammetry sweeps of electrolysis up to 1500 cycles. This work reveals a synergistic effect between metal atoms (Ce, Nd, and Pr) on nickel foam substrate is considered mainly responsible for the electron transfer mechanism and well-balanced kinetics under begin conditions.

Keywords: CeNdO2, Co-doping, Alkaline media, Oxygen evolution reaction, Mechanisim