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.