Accumulation of Long-Lived Photogenerated Holes at Indium Single Atom Catalysts via Two Coordinate Nitrogen Vacancy Defect Engineering for Enhanced Photocatalytic Oxidation.

Visible light-driven photocatalytic oxidation by photogenerated holes has immense potential for environmental remediation applications. While the electron-mediated photoreduction reactions are often at the spotlight, active holes possess a remarkable oxidation capacity that can degrade recalcitrant organic pollutants, resulting in non-toxic byproducts. However, the random charge transfer and rapid recombination of electron-hole pairs hinder the accumulation of long-lived holes at the reaction center. Herein, we report a novel method employing defect-engineered indium (In) single atom photocatalysts, dispersed in carbon nitride foam (In-Nv-CNF), to overcome these challenges and make further advances in photocatalysis. This Nv (nitrogen vacancy) defect-engineered strategy produces a remarkable extension in the lifetime of photogenerated holes and an increase in the concentration of photogenerated holes in In-Nv-CNF. Consequently, the optimized In-Nv-CNF demonstrates a remarkable 50-fold increase in photo-oxidative degradation rate compared to pristine CN, effectively breaking down two widely used antibiotics (tetracycline and ciprofloxacin) under visible light. The contaminated water treated by In-Nv-CNF has proven to be completely non-toxic based on the growth of E. coli before and after treatment. Structural-performance correlations between Nv defect engineering and long-lived hole accumulation in In-Nv-CNF are established and validated through experimental and theoretical agreement. This work has the potential to elevate the efficiency of overall photocatalytic reactions from a hole-centric standpoint. This article is protected by copyright. All rights reserved.