Bidirectional Progressive Optimization of Carbon and Nitrogen Defects in Solar-Driven Regenerable Adsorbent to Remove UV-Filters from Water

Defect engineering of nanomaterials has emerged as a promising approach to improve their performance for pollutant removal. However, various nanomaterial defects play variant roles in environmental applications. It is still a challenge to construct multiple defects of composite materials into advantageous aggregates to deal with complicated matrix pollution. In this work, we investigated a series of three-dimensional defect-optimized aerogels (3D DOAs) of graphene oxide (GO) with a covalent triazine framework (CTF) for improved adsorption and photoregeneration performance via tailoring duet carbon and nitrogen defects. Using chemical reduction, carbon defects in GO were gradually repaired and nitrogen defects in CTF were created simultaneously. The carbon defect engineering generated additional nonpolarized electron-depleted sites in GO of 3D DOA for increased adsorption capacities (2417 μmol/g for benzophenone, 2209 μmol/g for 4-hydroxybenzophenone, 1957 μmol/g for 2,2′,4,4′-tetrahydroxybenzophenone). Meanwhile, increasing nitrogen defects of the CTF in 3D DOA would produce midgap states for an extended absorption range of visible light and increased photocatalytic activity to remove adsorbed pollutants. The enhanced adsorption and the superior photocatalytic regeneration soundly corroborated that the performance of 3D DOA was improved effectively by the defect optimization strategy. Moreover, the high stability of 3D DOA and its practical usage were verified in a real water matrix with a 7-day cycle test. The present work highlights an approach of defect optimization for development of a solar-driven, self-regenerative adsorbent for water purification with high efficiency.