Au3SnP7@black phosphorus: an easy access to black phosphorus

Area of Science:

• Materials Science
• Solid-State Chemistry
• Elemental Chemistry

Background:

• Black phosphorus is a crucial allotrope of phosphorus with unique electronic properties.
• Traditional preparation methods often involve high pressures, toxic catalysts, or complex flux techniques.

Purpose of the Study:

• To develop a novel, low-pressure method for synthesizing high-quality black phosphorus.
• To investigate the formation mechanism and crystal structure of the synthesized black phosphorus.

Main Methods:

• Synthesis of black phosphorus from red phosphorus using gold, tin, and tin(IV) iodide at 873 K and low pressure.
• Redetermination of the crystal structure using single-crystal X-ray diffraction.
• Characterization using solid-state 31P Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectroscopy and X-ray powder diffraction.

Main Results:

• Successfully synthesized black phosphorus under low-pressure conditions.
• Observed additional phases including Au3SnP7, AuSn, and Sn4P3, with tin(IV) iodide remaining unreacted.
• Confirmed high crystal quality of black phosphorus through NMR and XRD.
• Redetermined crystal structure: space group Cmce, a = 3.316(1) Å, b = 10.484(2) Å, c = 4.379(1) Å.

Conclusions:

• The new preparation method is simple, effective, and avoids hazardous reagents or complex setups.
• Thermodynamic calculations suggest a kinetically controlled mechanism, not a thermodynamically controlled one, is responsible for the formation of orthorhombic black phosphorus.
• This method holds general interest for elemental phosphorus chemistry and materials science.