Water-Modulated Construction of Nanoclay/g-C₃N₄ Heterostructures for Selective Generation of Singlet Oxygen in...

Singlet oxygen (¹O₂), a highly selective oxidant in advanced oxidation processes, remains challenging to generate efficiently and exclusively due to competing radical pathways. Here, we report a water-modulated interlayer confinement strategy for constructing nanoclay/g-C₃N₄ heterostructures (RT/CN) that promote selective ¹O₂ production through tailored interfacial electronic modulation. By precisely tuning the rectorite-to-water ratio during precursor grinding, urea undergoes confined polymerization within the RT interlayers, forming ultrathin g-C₃N₄ nanosheets covalently anchored via Si-N-Al linkages. This asymmetric interfacial architecture induces localized electron redistribution, enabling peroxymonosulfate (PMS) activation through an oxidative, nonradical pathway while fully suppressing radical generation. The optimized RT/CN-H3 catalyst achieves dual-mode ¹O₂ production: interfacial electron transfer under dark conditions and hole-mediated enhancement under visible light. Remarkably, it delivers 96% degradation of Orange II in 30 min (k = 0.102 min^-1) under dark, with near-exclusive (∼100%) ¹O₂ selectivity. This scalable, metal-free platform demonstrates robust reactivity across diverse pollutants and environmental conditions. The work establishes a generalizable strategy for harnessing the interlayer confinement of natural minerals, with broader implications for sustainable oxidation chemistry, environmental remediation, and the rational design of green catalytic systems.