Fully Exposed Pd Ensembles on Ultrathin Co3O4 Nanosheets: A Reductive–Oxidative Dual-Active Catalyst for the Detoxification of Chlorophenol

The complete detoxification of hazardous organic pollutants is crucial for water treatment. However, this often requires the cooperation of multiple treatment processes catalyzed by different catalysts, leading to a complex water treatment infrastructure design and high operational costs. To address this challenge, we developed fully exposed palladium (Pd) ensemble (Pdn)-loaded ultrathin Co3O4 nanosheets (NSs) (Pdn/Co3O4 NSs) as a reductive–oxidative dual-active catalyst for the efficient detoxification of halogenated organic pollutants. During the treatment of simulated water contaminated by 4-chlorophenol (4-CP), a representative persistent organic pollutant, Pdn reactive centers rapidly hydrodechlorinate 4-CP into low-toxicity phenol with activity ≥10 times that of benchmark catalysts. The synergy between the Pd ensembles and oxygen vacancies further promotes the rapid and selective hydrogenation of phenol into cyclohexanone on Co3O4 NSs. Subsequently, cyclohexanone is oxidized by peroxymonosulfate (PMS) under Co3O4 activation. A cell assay-based toxicity study confirmed that stimulated polluted environmental water is fully detoxified after treatment with the designed Pdn/Co3O4 NSs catalyst. This study provides new insights into the rational design of Pd catalysts for the catalytic removal of persistent organic pollutants, particularly halogenated aromatics, paving the way for facile, low-cost, and highly efficient water treatment processes.