Polymer and cluster chemistry of tetravalent cerium in aqueous solutions - Comparison with tetravalent actinides

Cerium (Ce) is known to be the only lanthanide (Ln) which can be stabilized in the tetravalent state (i.e., Ce(IV)) in aqueous solutions. Owing to this chemical specificity, the aqueous chemistry of Ce(IV) shows unique characters as compared to that for the other Ln. For instance, due to its high charge density, the aqueous chemistry of Ce(IV) is predominantly characterised by strong hydrolysis. This strong hydrolysis results in the formation of a variety of hydroxide species even under acidic conditions.1 Moreover, the hydrolysis of Ce(IV) is often a primary step of many wet syntheses to yield nano-sized CeO2 particles which have many technological applications. Despite these chemical uniqueness and importance in applications, the aqueous chemistry of Ce(IV) is poorly understood even to date. Based on this background, this study aims to comprehensively understand the chemical behaviour of Ce(IV) in aqueous solutions by combining several spectroscopic (XAS, HEXS, DLS) and microscopic (TEM) techniques.