Revealing stable geometries and magic clusters of hexagonal boron nitride in the nucleation of chemical vapor deposition growth on Ni(111)/Cu(111) surfaces: a theoretical study

Revealing maleic acid role in the preparation of α-hemihydrate gypsum from titanium gypsum through experiments and DFT calculations

Titanium gypsum (TG) is rarely used to produce α-hemihydrate gypsum (α-HH) because of its poor crystallinity and high impurity and moisture contents. Here, a method is proposed to prepare α - HH by adjusting the reaction temperature, CaCl2 solution concentration and maleic acid dosage based on acid leaching and heat-treated TG as raw material. The effect of maleic acid and Fe3+ ions on the preparation of α-HH were systematically analyzed using density functional theory (DFT) and typical materials characterization methods, X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Under the optimal conditions (CaCl2 concentration of 23 % and reaction temperature of 95 °C), the maleic acid is chemically adsorbed on the crystal surfaces of α-HH, the strongest adsorption is in the (111) surface. Increasing the maleic acid concentration from 0 to 0.15 % decreased the aspect ratio of the α-HH crystals from 8.26 to 0.96, respectively, where the optimal dosage was 0.1 %. The theoretical results proved that the substitution energy of Fe3+ was greater than that of Ca2+, and Fe3+ ions can spontaneously enter the α-HH lattice to replace Ca2+ ions. Furthermore, the adsorption energy of maleic acid on the (111) surface increased after the substitution of Fe3+ to generate a synergistic effect that hinders α-HH growth along the c-axis, resulting in the preferred morphology. The results of this study provide a new method for using waste TG to produce a high-value-added product.

Dissociation of ammonia borane and its subsequent nucleation on the Ru(0001) surface Revealed by density functional theoretical simulations

Chemical vapor deposition (CVD) method is widely used in preparation of graphene, hexagonal boron nitride (h-BN) and other 2D materials. To improve the quality of h-BN, it is essential to...

Revealing initial nucleation of hexagonal boron nitride on Ru(0001) and Rh(111) surfaces by density functional theory simulations

The nucleation of h-BN on Ru(0001) and Rh(111) surfaces via an energy-driven process is systematically studied by density functional theory simulations.

Isolated Ni atoms induced edge stabilities and equilibrium shapes of CVD-prepared hexagonal boron nitride on the Ni(111) surface

The edge stability and equilibrium shape of h-BN passivated by isolated Ni atoms are revealed by density functional theory simulations.