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

Abstract 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 nontoxic 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, a novel method employing defect‐engineered indium (In) single‐atom photocatalysts with nitrogen vacancy (Nv) defects, dispersed in carbon nitride foam (In‐Nv‐CNF), is reported to overcome these challenges and make further advances in photocatalysis. This Nv defect‐engineered strategy produces a remarkable extension in the lifetime 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 is completely nontoxic based on the growth of Escherichia coli . Structural–performance correlations between 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.