Visible‐Light‐Driven Ammonia Photosynthesis on Mo ₇ ‐Cluster Stabilized CeO ₂ Nanocore Through Interfacial Charge Transfer

Abstract A [Mo ₇ O ₂₄ ] ⁶⁻ ‐cluster is used herein to stabilize a vacancy‐rich CeO ₂ nanocore (Mo ₇ @CeO ₂ ) with high aqueous dispersity and wide‐pH stability, possessing a band structure to harvest the visible‐light for photoreduction of [NO ₃ ] ⁻ to ammonia. Covalent‐type atomic connectivity of the Mo ₇ ‐clusters to CeO ₂ nanocore is established by advanced spectroscopies. In situ electron paramagnetic resonance (EPR) with photogenerated hole and electron capturing reagents, femtosecond transient absorption spectroscopy (fs‐TAS), and in situ Kelvin probe atomic force microscopy (KPFM) studies probe the interfacial charge transfer in this type‐II heterostructure, which favors the efficient exciton separation and enhances the lifetime for the photosynthesis of NH ₃ (>95%) with an exceptionally high yield rate ≈332 mg h ⁻¹ . A computational study emphasizes an internal electric field (IEF) formation and hole retention on the CeO ₂ and electron localization in the Mo ₇ cluster. ¹⁵ N‐labeling study confirms the source of nitrogen in photogenerated NH _3, while pH‐variation and D‐labelling studies infer that the photochemical deoxygenation of nitrate is coupled with hydrogenation. This study highlights the pivotal role of an inorganic ligand in regulating the size of the metal‐oxide core, modulating the band alignment, and charge transfer dynamics for photoconversion, which is further demonstrated as a potential strategy for ammonia photosynthesis using wastewater and sunlight.