Oxygen Vacancy Assisted Hydrogen Evolution Reaction over CeO2 based Solid Solutions

Abstract

Producing sustainable hydrogen through water electrolysis is a promising approach to meet the growing demand for renewable energy storage. Developing affordable and efficient electrocatalysts made from non-precious metals to replace platinum-based catalysts for hydrogen evolution reactions (HER) continues to be a significant challenge. In the present study, pristine CeO2 and doped solid solutions Ce0.95Co0.05O2–δ, Ce0.95Ni0.05O2–δ and Ce0.95Cu0.05O2–δ were evaluated for HER, and the electrochemical studies in alkaline medium showed superior HER activity for the doped catalysts, with Ce0.95Ni0.05O2–δ achieving the lowest overpotential and highest mass activity, comparable to Pt/C. Tafel slopes and EIS measurements suggested a Volmer–Heyrovsky mechanism facilitated by oxygen vacancies and hydrogen spill-over. Stability tests confirmed the durability of Ce0.95Ni0.05O2–δ under prolonged HER conditions. This study highlights aliovalent doping as a viable strategy for engineering oxygen vacancies and enhancing CeO2-based catalysts for alkaline water electrolysis.