Structural Dynamics Behind the Formation of α′-Ni₃Ga Alloy Nanoparticles from a Ni–Ga Phyllosilicate Dispersed on Silica Using X-ray Probes
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Date
2025-07-22
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Journal Article
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Abstract
This study investigates the structural evolution during the formation of α′-Ni₃Ga alloy nanoparticles from Ni–Ga phyllosilicate sheets upon heating in H₂. The phyllosilicate sheets were produced through a deposition–precipitation process using Ni and Ga nitrates and colloidal SiO₂. Advanced characterization techniques, including X-ray absorption spectroscopy, pair distribution function analysis, and electron microscopy, revealed the structure of the chrysotile-type phyllosilicates. Such phyllosilicates are composed of brucite-like layers with Ni²⁺ in octahedral coordination with oxygen (NiO₆), intercalated by layers of silica tetrahedra (SiO₄). Ga³⁺ ions partially replaced Ni²⁺ in octahedral positions within the brucite-like layers, but are also found in tetrahedral coordination, substituting Si⁴⁺ within the SiO₄ layers of the phyllosilicate phase and/or dispersed on/in the surface of the amorphous SiO₂ support. The structural transformation of the precursor material during thermal activation in H₂ was monitored by d-PDF and XAS. It was observed that the decomposition of the Ni–Ga phyllosilicate starts in the temperature range 290–310 °C, resulting in the formation of small nickel-rich nanoparticles and gallium oxide (GaOx) species. As the temperature is increased, Ga is reduced and is incorporated into the metallic nickel structure, ultimately forming intermetallic α′-Ni₃Ga nanoparticles with an average size of about 5 nm. Our findings provide a detailed mechanistic understanding of the structural evolution of the phyllosilicate-based precursor, including alloy/intermetallic formation under thermal reduction conditions and highlight the potential of mixed-metal phyllosilicates as precursors for bimetallic catalysts.
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37 (14)
Pages / Article No.
5312 - 5324
Publisher
American Chemical Society
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Subject
Extended X-Ray Absorption Fine Structure; Layers; Materials; Scattering; X-Ray Absorption Near Edge Spectroscopy
Organisational unit
03865 - Müller, Christoph R. / Müller, Christoph R.
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Funding
183495 - Tailored CO2 Hydrogenation Catalysts for Selective Methanol Synthesis via Structure-Activity Relationship across Time and Length Scale (SNF)
224646 - Deciphering the structural descriptors of bimetallic catalysts that control their activity and selectivity through operando electron total scattering analysis. (SNF)
180544 - NCCR Catalysis (phase I) (SNF)
ETH-18 22-1 - Supported intermetallic nanocrystals: investigating structure – catalytic performance relationships via in situ and operando studies (ETHZ)
819573 - Advancing CO2 Capture Materials by Atomic Scale Design: the Quest for Understanding (EC)
225147 - NCCR Catalysis (51NF40_225147): Flexibility Grant (SNF)
224646 - Deciphering the structural descriptors of bimetallic catalysts that control their activity and selectivity through operando electron total scattering analysis. (SNF)
180544 - NCCR Catalysis (phase I) (SNF)
ETH-18 22-1 - Supported intermetallic nanocrystals: investigating structure – catalytic performance relationships via in situ and operando studies (ETHZ)
819573 - Advancing CO2 Capture Materials by Atomic Scale Design: the Quest for Understanding (EC)
225147 - NCCR Catalysis (51NF40_225147): Flexibility Grant (SNF)