Cs₂Ge₃In₆Se₁₄: A Structure Transformation Driven by the Size Preference and Its Properties

Area of Science:

• Inorganic Chemistry
• Solid-State Chemistry
• Materials Science

Background:

• Exploration of novel chalcogenides for advanced applications.
• Understanding structure-property relationships in complex inorganic compounds.

Purpose of the Study:

• Discover and characterize a new ternary selenide, Cs₂Ge₃In₆Se₁₄.
• Investigate its structural, electronic, and photocatalytic properties.
• Compare its performance to related materials and commercial standards.

Main Methods:

• Solid-state reaction synthesis at 1173 K.
• Single-crystal X-ray diffraction for structural determination.
• X-ray Photoelectron Spectroscopy (XPS) and Electron Localization Function (ELF) analyses for electronic structure.
• UV-Vis spectroscopy for band gap determination.
• Photocatalytic degradation experiments using Rhodamine B (RhB).

Main Results:

• Discovery of Cs₂Ge₃In₆Se₁₄ with a novel structure type (space group R3̅ m).
• Identification of mixed-valence germanium (Ge²⁺/Ge³⁺) and Ge-Ge metallic bonding.
• Observed a structural transformation from R3̅ m to P3̅ m1 in related compounds, driven by dimer size.
• Determined a band gap of 2.08 eV.
• Demonstrated efficient photodegradation of RhB under visible light, exceeding P25 performance.

Conclusions:

• Cs₂Ge₃In₆Se₁₄ is a new inorganic material with unique structural and electronic features.
• The material shows promising photocatalytic activity for environmental remediation.
• Structural transformations in related compounds are influenced by dimer size preferences.