Concerted Reactive Adsorption and Photocatalytic Degradation of Bisphenol-S on Molybdenum Cluster-Modified Nanoceria

Bisphenol-S (BPS) is a widespread toxic industrial pollutant and endocrine disruptor of growing environmental concern. This study investigates the use of porous nanoceria particles (CeO₂) functionalized with octahedral molybdenum clusters (Mo₆) for the removal of waterborne BPS through a combined mechanism of reactive adsorption and photodegradation. Although immobilization of Mo₆ cluster reduced the overall surface area of CeO₂, BPS adsorption and partial decomposition in the dark were enhanced due to chemical specificity and surface interactions introduced by the Mo₆ clusters. Upon UV-A irradiation, quenching of the phosphorescence of the clusters indicated photoinduced electron transfer from Mo₆ to CeO₂, which facilitated hydroxyl radical generation and improved BPS photocatalytic degradation. Unlike bare nanoceria, the Mo₆@CeO₂ composite initially retained the intermediate 4-hydroxybenzenesulfonic acid formed in the dark, but subsequently released it, along with phenol and other degradation products, under light. This controlled photodesorption was coupled with stable performance over multiple degradation cycles. Under simulated solar irradiation, the composite achieved a 3-fold increase in BPS removal efficiency compared to bare nanoceria. These findings highlight the synergistic interplay between Mo₆ clusters and nanoceria and reflects the potential of this composite material for effective water remediation.