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
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
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/Îł-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/Îł-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
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