Long-range electronic interactions of tubular single-atom Cu-N₃ catalysts for nanoconfined direct electron transfer oxidation

Abstract

Leveraging atomically dispersed catalysts to selectively trigger nonradical oxidation can overcome the short lifetimes and poor selectivity of radical-based processes in water treatment. Here, we integrate long-range electronic modulation with nanoconfinement by embedding isolated Cu-N₃ sites into carbon-doped tubular carbon nitride (CuTCN/C). Carbon atoms intrinsic to the support upshift the Cu d-band center, which strengthens peroxymonosulfate (PMS) adsorption and lowers the activation energy barrier. Moreover, surface mesopores greatly enrich local PMS concentration in the nanoconfined environment and accelerate interfacial electron migration to coordinate a direct electron transfer pathway. As a result, CuTCN/C delivers the highest activity among Cu single-atom catalysts, while operating with minimal PMS doses due to the remarkably accelerated mass transfer. Spectroscopic, electrochemical, DFT and MD analyses confirm the synergistic roles of electronic tuning and nanoconfinement in promoting oriented PMS activation as reactive surface complex that directly attacks surface-enriched pollutants with high PMS utilization efficiency. The continuous fluidized-bed tests demonstrate strong salt tolerance and long-term stability of the system, while life-cycle assessment confirms favorable environmental metrics in practical application. This dual engineering strategy of macroscopic morphological and microscopic electronic structure provides a blueprint for smart design of robust single-atom catalysts for selective and high-efficiency water purification.