Confinement-Modulated Singlet-Oxygen Nanoreactors for Water Decontamination

Water decontamination with singlet oxygen (¹O₂) has shown advantages over the traditional radical-based treatment processes, which are frequently inhibited by the background inorganic/organic substances and produce toxic byproducts. However, earlier reported treatment systems mostly suffer from side reactions against efficient and cost-effective production of ¹O₂, together with insufficient utilization of ¹O₂ limited by the extremely short diffusion length. To overcome the drawbacks, we here designed high-performance nanoreactors by modulating the MnO₂ phase to nanotube structures (with ∼5 nm diameter, termed "NT₅"). With nanoconfinement, our developed NT₅ directed efficient and almost 100% utilization of peroxymonosulfate (PMS) to produce ¹O₂ and achieved maximal kinetics on organic pollutant elimination. The mechanism study revealed that the geometric strain of NT₅ together with spatial confinement modulated the adsorption properties of PMS molecules and led to their transformation to ¹O₂. To demonstrate the applicability of NT₅, we developed a reactive filter with a particulate catalyst (NT₅ grown on an alumina substrate) that can effectively and stably work in a broad range of contaminated scenarios (surface water, groundwater, municipal secondary effluent, and industrial wastewaters), due to the confined treatment together with the fouling-resistance nature. Our study may boost the deployment of nanomaterials with confined catalysis and their applications in practical water treatment scenarios.