Self-limiting synthesis of Au–Pd core–shell nanocrystals with a near surface alloy and monolayer Pd shell structure and their superior catalytic activity on the conversion of hexavalent chromium

Li, Xiaokun; Li, Cuixia; Xiang, Dong; Zhang, Chun-Mei; Lü, Xin; Liu, Xingyu; Zheng, Fuqin; Xie, Xiaoyu; Zhang, Youlin; Chen, Wei

doi:10.1016/j.apcatb.2019.04.071

Cited by 37 publications

(13 citation statements)

References 49 publications

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“…Study of effect of morphologies of nanocatalysts on catalytic reduction of Cr(VI) may be a fascinating subject of future studies. Core-shell bimetallic nanoparticles have been reported for catalytic Cr(VI) reduction ( Li et al, 2019 ) but effect of shell thickness and core size and exchange of core metal by shell metal may an interesting subject of future studies. Transition metal like manganese, copper and cobalt etc.…”

Section: Discussionmentioning

confidence: 99%

Inorganic nanoparticles for reduction of hexavalent chromium: Physicochemical aspects

Farooqi

Akram

Begum

et al. 2021

Journal of Hazardous Materials

107

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Section: Discussionmentioning

confidence: 99%

Inorganic nanoparticles for reduction of hexavalent chromium: Physicochemical aspects

Farooqi

Akram

Begum

et al. 2021

Journal of Hazardous Materials

107

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“…At present, the methods for reducing the Cr(VI) concentration in aqueous solutions mainly include electrochemical precipitation, ion exchange, membrane filtration, photocatalytic degradation, and adsorption [ 10 , 11 , 12 , 13 , 14 ]. The reduction of Cr(VI) to less toxic Cr(III) by semiconductor photocatalytic technology is considered an effective, low-cost method that generates no harmful substances [ 15 , 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

Spherical Bi2WO6/Bi2S3/MoS2 n-p Heterojunction with Excellent Visible-Light Photocatalytic Reduction Cr(VI) Activity

Ren

Gong

et al. 2020

Nanomaterials

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Exploiting excellent photocatalytic activity and stable heterostructure composites are of critical importance for environmental sustainability. The spherical Bi2WO6/Bi2S3/MoS2 n-p heterojunction is first prepared via an in situ hydrothermal method using Bi2WO6, Na2MoO4·2H2O, and CH4N2S, in which the intermediate phase Bi2S3 is formed due to chemical coupling interaction of Bi2WO6 and CH4N2S. Scanning electron microscopy indicates that the compactness of the sample can be easily adjusted by changing the contents of S and Mo sources in the solution. The results of ultraviolet–visible (UV–vis) diffuse reflectance spectra, photoluminescence, transient photocurrent response, and electrochemical impedance spectra indicate that the formation of heterojunctions contributes to enhancing visible-light utilization and promoting photogenerated carrier separation and transfer. The composite material is used as a catalyst for the visible light photocatalytic reduction of Cr(VI). Remarkably, the optimal Bi2WO6/Bi2S3/MoS2 n-p heterojunction achieves the greatest Cr(VI) reduction rate of 100% within 75 min (λ > 420 nm, pH = 2); this rate is considerably better than the Cr(VI) reduction rate of pure Bi2WO6. The recycling experiment also reveals that the photocatalytic performance of the n-p heterojunction toward Cr(VI) is still maintained at 80% after three cycles, indicating that the n-p heterojunction has excellent structural stability. The capture experiment proves that the main active species in the system are electrons. The reasonable mechanism of Bi2WO6/Bi2S3/MoS2 photocatalytic reduction Cr(VI) is proposed. Our work provides new research ideas for the design of ternary heterojunction composites and new strategies for the development of photocatalysts for wastewater treatment.

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“…High-resolution elemental mapping enables the determination of concentration profiles of the two metals for comparison to a transport model. Our model is based on intrinsic properties of the two metal components with no fitting parameters and can be generalized to other alloying systems. , Systems such as Cu–Ag, Au–Ni, and Au–Pt have positive heats of mixing that favor phase-segregation whereas systems such as Pt–Pd, Ag–Au, and Ni–Pd have negative heats of mixing that enable alloying . Galvanic replacement could also be used in tandem with other postsynthetic steps when synthesizing more complex geometries or multicomponent nanostructures.…”

mentioning

confidence: 99%

Self-Limiting Shell Formation in Cu@Ag Core–Shell Nanocrystals during Galvanic Replacement

Kamat

Yan

Osowiecki

et al. 2020

J. Phys. Chem. Lett.

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The understanding of synthetic pathways of bimetallic nanocrystals remains limited due to the complex energy landscapes and dynamics involved. In this work, we investigate the formation of self-limiting Cu@Ag core–shell nanoparticles starting from Cu nanocrystals followed by galvanic replacement with Ag ions. Bulk quantification with atomic emission spectroscopy and spatially resolved elemental mapping with electron microscopy reveal distinct nucleation regimes that produce nanoparticles with a tunable Ag shell thickness, but only up to a certain limiting thickness. We develop a quantitative transport model that explains this observed self-limiting structure as arising from the balance between entropy-driven interdiffusion and a positive mixing enthalpy. The proposed model depends only on the intrinsic physical properties of the system such as diffusivity and mixing energy and directly yields a high level of agreement with the elemental mapping profiles without requiring additional fit parameters.

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Self-limiting synthesis of Au–Pd core–shell nanocrystals with a near surface alloy and monolayer Pd shell structure and their superior catalytic activity on the conversion of hexavalent chromium

Cited by 37 publications

References 49 publications

Inorganic nanoparticles for reduction of hexavalent chromium: Physicochemical aspects

Inorganic nanoparticles for reduction of hexavalent chromium: Physicochemical aspects

Spherical Bi2WO6/Bi2S3/MoS2 n-p Heterojunction with Excellent Visible-Light Photocatalytic Reduction Cr(VI) Activity

Self-Limiting Shell Formation in Cu@Ag Core–Shell Nanocrystals during Galvanic Replacement

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