A mixed valence decanuclear cerium-oxo cluster CeIII4CeIV6 for efficient photocurrent response

Abstract

Cerium-oxo clusters with mixed valence exhibit distinctive redox properties due to cerium ions switch between +3/+4 valence states. However, the design and synthesis of these clusters present formidable challenges, resulting in limited availability of such species, often necessitating the use of both CeIII and CeIV reactants. Herein, we successfully obtained a mixed valence cerium-oxo cluster CeIII4CeIV6(µ3-O)4(µ4-O)4(acac)14(CH3O)6(CH3OH)2 (CeIII4CeIV6, Hacac = acetylacetone) through low-temperature crystallization only using the trivalent cerium salt. The coexistence as well as the distribution of Ce ions in different valence states have been determined from a multifaceted analysis. In addition, the stability of the synthesized cluster was confirmed by the HRESI-MS study through redissolution of the single crystal sample in fresh methanol. Importantly, Importantly, this study reveals the mechanism for the generation of +4 valence state. Under alkaline conditions, the presence of trace oxygen and the involvement of acetylacetone ligand facilitated the partial oxidation of CeIII to CeIV. The cluster CeIII4CeIV6 has strong ultraviolet absorption and long visible light absorption. As the electrode precursor, CeIII4CeIV6 showed clear photocurrent response and high photocurrent intensity due to CeIII/CeIV redox reaction.