Photoexcited Hole‐Enabled Synthesis of Surface High‐Valent Cobalt‐Oxo Species with Water as the Oxygen Atom Source for Water Purification

Abstract

Abstract High‐valent cobalt‐oxo species (Co IV ═O) are key intermediates in catalytic chemistry but suffer a great challenge in their efficient and mild synthesis due to the strong electronic repulsion between the cobalt center and the oxygen ligand. Herein, we report a new approach to synthesizing surface Co IV ═O on the Co 3 O 4 /BiVO 4 (CoBi) catalyst via a photoexcited hole‐induced process using water as the oxygen atom source. The interfacial Co 2+ ─O─Bi 3+ bonds act as the atomic‐level channels to directionally transport photoexcited holes driven by the internal electric field effect. It has been found that H 2 O was photolyzed to cobalt‐coordinated hydroxyls that were turned to Co IV ═O via a photoexcited hole‐induced deprotonation. The isotopic labeling experiments confirmed that the oxygen atom source of Co IV ═O was derived from water rather than chlorite. A synergistic effect was formed between photocatalysis and transition metal‐catalyzed chlorite activation, which enhanced the degradation of sulfadiazine (SDZ) and elevated the conversion ratio of chlorite to chlorine dioxide (ClO 2 ) from 40% to 60%. The present work has elucidated the essential role of H 2 O and photoexcited holes in the formation of Co IV ═O and provides a viable strategy to synthesize surface high‐valent metal species utilizing ubiquitous water and sunlight for water purification.