3 research outputs found

    Fully Exposed Pd Ensembles on Ultrathin Co<sub>3</sub>O<sub>4</sub> Nanosheets: A Reductive–Oxidative Dual-Active Catalyst for the Detoxification of Chlorophenol

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    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

    AuFe<sub>3</sub>@Pd/Îł-Fe<sub>2</sub>O<sub>3</sub> Nanosheets as an In Situ Regenerable and Highly Efficient Hydrogenation Catalyst

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    Heterogenous Pd catalysts play a pivotal role in the chemical industry; however, it is plagued by S2– or other strong adsorbates inducing surface poisoning long term. Herein, we report the development of AuFe3@Pd/γ-Fe2O3 nanosheets (NSs) as an in situ regenerable and highly active hydrogenation catalyst. Upon poisoning, the Pd monolayer sites could be fully and oxidatively regenerated under ambient conditions, which is initiated by •OH radicals from surface defect/FeTetra vacancy-rich γ-Fe2O3 NSs via the Fenton-like pathway. Both experimental and theoretical analyses demonstrate that for the electronic and geometric effect, the 2–3 nm AuFe3 intermetallic nanocluster core promotes the adsorption of reactant onto Pd sites; in addition, it lowers Pd’s affinity for •OH radicals to enhance their stability during oxidative regeneration. When packed into a quartz sand fixed-bed catalyst column, the AuFe3@Pd/γ-Fe2O3 NSs are highly active in hydrogenating the carbon–halogen bond, which comprises a crucial step for the removal of micropollutants in drinking water and recovery of resources from heavily polluted wastewater, and withstand ten rounds of regeneration. By maximizing the use of ultrathin metal oxide NSs and intermetallic nanocluster and monolayer Pd, the current study demonstrates a comprehensive strategy for developing sustainable Pd catalysts for liquid catalysis

    Au@Pd Bimetallic Nanocatalyst for Carbon–Halogen Bond Cleavage: An Old Story with New Insight into How the Activity of Pd is Influenced by Au

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    AuPd bimetallic nanocatalysts exhibit superior catalytic performance in the cleavage of carbon–halogen bonds (C–X) in the hazardous halogenated pollutants. A better understanding of how Au atoms promote the reactivity of Pd sites rather than vaguely interpreting as bimetallic effect and determining which type of Pd sites are necessary for these reactions are crucial factors for the design of atomically precise nanocatalysts that make full use of both the Pd and Au atoms. Herein, we systematically manipulated the coordination number of Pd–Pd, d-orbital occupation state, and the Au–Pd interface of the Pd reactive centers and studied the structure–activity relationship of Au–Pd in the catalyzed cleavage of C–X bonds. It is revealed that Au enhanced the activity of Pd atoms primarily by increasing the occupation state of Pd d-orbitals. Meanwhile, among the Pd sites formed on the Au surface, five to seven contiguous Pd atoms, three or four adjacent Pd atoms, and isolated Pd atoms were found to be the most active in the cleavage of C–Cl, C–Br, and C–I bonds, respectively. Besides, neighboring Au atoms directly contribute to the weakening of the C–Br/C–I bond. This work provides new insight into the rational design of bimetallic metal catalysts with specific catalytic properties
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