Single-Atom\nCobalt Incorporated in a 2D Graphene Oxide\nMembrane for Catalytic Pollutant Degradation

We introduce a new graphene oxide\n(GO)-based membrane architecture\nthat hosts cobalt catalysts within its nanoscale pore walls. Such\nan architecture would not be possible with catalysts in nanoscale,\nthe current benchmark, since they would block the pores or alter the\npore structure. Therefore, we developed a new synthesis procedure\nto load cobalt in an atomically dispersed fashion, the theoretical\nlimit in material downsizing. The use of vitamin C as a mild reducing\nagent was critical to load Co as dispersed atoms (Co<sub>1</sub>),\npreserving the well-stacked 2D structure of GO layers. With the addition\nof peroxymonosulfate (PMS), the Co<sub>1</sub>-GO membrane efficiently\ndegraded 1,4-dioxane, a small, neutral pollutant that passes through\nnanopores in single-pass treatment. The observed 1,4-dioxane degradation\nkinetics were much faster (>640 times) than the kinetics in suspension\nand the highest among reported persulfate-based 1,4-dioxane destruction.\nThe capability of the membrane to reject large organic molecules alleviated\ntheir effects on radical scavenging. Furthermore, the advanced oxidation\nalso mitigated membrane fouling. The findings of this study present\na critical advance toward developing catalytic membranes with which\ntwo distinctive and complementary processes, membrane filtration and\nadvanced oxidation, can be combined into a single-step treatment.