Ultrathin heteroatom-doped CeO2 nanosheet assemblies for durable oxygen evolution: Oxygen vacancy engineering to trigger deprotonation

Heteroatom-doped ultrathin CeO2 nanosheets assemblies activate as an efficient OER electrocatalyst through reduced deprotonation barrier for OH, enhanced conductivity, and increased active sites, owing to the generation of Ce3+ defect-associated OVs. [Display omitted] The manipulation of oxygen vacancies (OVs) in metal oxides has progressively emerged as a versatile strategy for improving their catalytic performance. In this study, we aim to enhance the oxygen evolution reaction (OER) performance of cerium oxide (CeO2) by doping heteroatoms (Fe, Co, Ni) to generate additional OVs. We systematically analyzed both the morphology and electronic structure of the obtained CeO2 catalysts. The experimental results revealed the self-assembly of two-dimensional (2D) CeO2 nanosheets, with an approximate thickness of ∼1.7 nm, into 2D nanosheet assemblies (NSAs). Moreover, the incorporation of heteroatoms into the CeO2 matrix promoted the formation of OVs, resulting in a significant enhancement of the OER performance of CeO2. Among them, the Co-doped CeO2 NSAs sample displayed the highest activity and durability, with almost negligible activity loss during extended operating periods. The roles of heteroatom doping in improving OER activity were explored by DFT calculations. The produced OVs improve the adsorption of hydroxyl groups (OH−), promote the deprotonation process, and increase more active sites. These findings suggest that doping CeO2 with heteroatoms is a promising strategy for improving electrocatalytic OER activity, with great potential for the development of clean energy technologies, including but not limited to water splitting and fuel cells.