Heterointercalation in Chevrel-Phase Sulfides: A Model Periodic Solid for the Investigation of Chain Electron...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Electron density localization in periodic solids influences catalytic activity.
• Interstitial cations can modulate electronic structures in crystal lattices.

Purpose of the Study:

• Synthesize and characterize novel heterointercalant Chevrel-phase (CP) sulfides.
• Investigate the effect of intercalant composition on electronic structure and CO2 reduction selectivity.
• Establish design principles for advanced catalytic materials.

Main Methods:

• Microwave-assisted solid-state synthesis of Cu_xM_yMo_6S_8 (M = Cr, Mn, Fe, Ni).
• Structural analysis using powder X-ray diffraction (PXRD), Rietveld refinement, high-resolution transmission electron microscopy (HR-TEM), and selected-area electron diffraction (SAED).
• Electronic structure investigation via X-ray photoelectron spectroscopy (XPS) and X-ray absorption analysis (XAS).
• Electrochemical CO2 reduction and formaldehyde to methanol conversion studies.

Main Results:

• Successfully synthesized four heterointercalant CP sulfides.
• Demonstrated electron transfer from intercalated cations to the Mo6S8 cluster, altering electron density distribution.
• Observed enhanced selectivity towards methanol production during electrochemical CO2 reduction at low overpotentials (-0.5 V vs RHE).
• Achieved ~78% faradaic efficiency for methanol production from formaldehyde on Cu_xNi_yMo_6S_8.

Conclusions:

• Intercalant choice in CP sulfides significantly impacts electronic structure and catalytic performance.
• Electron transfer modulation is a key strategy for designing selective electrocatalysts.
• The findings provide a framework for designing materials for CO2 reduction and other catalytic applications.