Tailored oxygen vacancy engineering in hierarchical ceria-based materials: A pathway to high-efficiency solar hydrogen generation

Tailored oxygen vacancy engineering in ceria-based materials offers a transformative pathway toward efficient solar thermochemical hydrogen production. This review presents a focused and technically deep examination of how aliovalent doping and hierarchical nanoarchitecturing synergistically modulate oxygen vacancy formation, mobility, and redox thermodynamics. We begin by exploring the electronic structure and defect chemistry of ceria, followed by detailed analysis of dopant-induced vacancy stabilization mechanisms and morphology-driven effects on surface reactivity and strain. Special emphasis is placed on case studies involving doped mesoporous and inverse opal structures that demonstrate enhanced H2 yields and oxygen exchange kinetics. Advanced in situ and operando spectroscopies reveal dynamic defect behavior under realistic cycling conditions, while machine learning and high-throughput DFT approaches are enabling data-driven optimization of defect landscapes. The integration of these insights into closed-loop design frameworks offers a compelling vision for next-generation ceria-based materials, advancing the scalability and sustainability of solar hydrogen production technologies.