Metal phosphorous trichalcogenide is an important group of layered two-dimensional (2D) materials with potentially diverse applications in low-dimensional magnetic and spintronic devices. Herein we present a comprehensive investigation on the lattice dynamics and spin–phonon interactions of mechanically exfoliated atomically thin 2D magnetic material—iron phosphorus trisulfide (FePS ₃ ) by Raman spectroscopy and first principle calculations. Layer-number and temperature dependent Raman spectroscopy suggests a magnetic persistence in FePS ₃ even down to monolayer regime through the spin–phonon coupling, while the Néel temperature decreases from 117 K in bulk to 104 K in monolayer sample. Our studies advocate the intriguing magnetic properties in 2D crystals and suggest that FePS ₃ is a promising candidate material for future magnetic applications.

Graphitic carbon nitride (g-C₃N₄), a metal-free semiconductor with a band gap of 2.7 eV, has received considerable attention owing to its fascinating photocatalytic performances under visible-light. g-C₃N₄ exhibits high thermal and chemical stability and non-toxicity such that it has been considered as the most promising photocatalyst for environmental improvement and energy conservation. Hence, it is of great importance to obtain high-quality g-C₃N₄ and gain a clear understanding of its optical properties. Herein, we report a high-yield synthesis of g-C₃N₄ products via heating of high vacuum-sealed melamine powder in an ampoule at temperatures between 450 and 650 °C. Using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the chemical composition and crystallization of the as-produced g-C₃N₄ are demonstrated. A systematic optical study of g-C₃N₄ is carried out with several approaches. The optical phonon behavior of g-C₃N₄ is revealed by infrared and Raman spectroscopy, and the emission properties of g-C₃N₄ are investigated using photoluminescence (PL) spectroscopy, while the photocatalytic properties are explored by the photodegradation experiment.