Theoretical investigation on the nature of substituted benzene···AuX interactions: covalent or noncovalent?

The nature of coinage-metal bonds between AuX (X = F, Cl, Br, CN, NO2, CH3) and aromatic moieties with different electronic properties (benzene, 1,3,5-trifluorobenzene and hexafluorobenzene) has been characterized within...

Construction of Chemically Bonded Interface of Organic/Inorganic g-C3N4/LDH Heterojunction for Z-Schematic Photocatalytic H2 Generation

The design and synthesis of a Z-schematic photocatalytic heterostructure with an intimate interface is of great significance for the migration and separation of photogenerated charge carriers, but still remains a challenge. Here, we developed an efficient Z-scheme organic/inorganic g-C3N4/LDH heterojunction by in situ growing of inorganic CoAl-LDH firmly on organic g-C3N4 nanosheet (NS). Benefiting from the two-dimensional (2D) morphology and the surface exposed pyridine-like nitrogen atoms, the g-C3N4 NS offers efficient trap sits to capture transition metal ions. As such, CoAl-LDH NS can be tightly attached onto the g-C3N4 NS, forming a strong interaction between CoAl-LDH and g-C3N4 via nitrogen–metal bonds. Moreover, the 2D/2D interface provides a high-speed channel for the interfacial charge transfer. As a result, the prepared heterojunction composite exhibits a greatly improved photocatalytic H2 evolution activity, as well as considerable stability. Under visible light irradiation of 4 h, the optimal H2 evolution rate reaches 1952.9 μmol g−1, which is 8.4 times of the bare g-C3N4 NS. The in situ construction of organic/inorganic heterojunction with a chemical-bonded interface may provide guidance for the designing of high-performance heterostructure photocatalysts.

Using a CO2 Laser-Firing as a Clean Production Method to Form an Electrical Conductivity Surface and Color-Changing on Craft Ceramic.

Craft ceramic is an old industry. Most craft clay needs to be fired in a kiln, but kilns are expensive and inefficient [Kiln firing thermal efficiency: Kiln body heat storage 18.67%, Exhaust Sensible Heat 45.9%, Heat loss from incomplete combustion 16.24%, Radiated Conduction and Other Loss of Heat 12.61%]. In order to change the color of ceramic, potters commonly use kiln reduction firing. This technique requires an additional step and more fuel, which creates more air pollution. In this study, we used a CO2 laser to fire craft clay and glaze. This process not only changes the ceramic’s color but also changes the conductivity of the ceramic’s surface. By changing the composition of the glaze, the ceramic’s surface resistance was altered. Most kiln-fired ceramics are non-conductive because oxides are combined by covalent bonds. During the laser firing process, the covalent bonds become metal bonds. This new firing technique produces ceramic products that are superior in terms of light, heat, magnetism, and electricity. Thus, laser firing adds more function to the final ceramic product than kiln firing does. As opposed to kiln firing, there is no air pollution associated with CO2 laser firing. In comparison to kiln firing, laser-firing reduces both heat waste and air pollution by 99%. This study is based on our patented laser ceramic reduction firing technique. (Taiwan, R.O.C Patent Number: I687394) We recommend additional studies into laser firing in order to collect more data on laser-based ceramic production. Range: 20W laser

First-Principles Study on Al/Al3Hf Heterogeneous Nucleation Interface

Using first-principles method, the work of adhesion (Wad) and electronic structure of Al3Hf (001)/Al (001) interface are studied and the mechanism of Al3Hf as enhanced heterogeneous nucleus of α-Al are discussed. The results indicate that Al + Hf-termination interfaces with same stacking sequence and the HCP (Al atom locating on top of the Al3Hf slab) interface with the same termination have maximum Wad and minimum interface energy (yint), and therefore they are more stable ones. It is noteworthy that Al + Hf-terminated interface with HCP is most steady one. The stacking of Al atoms on Al3Hf substrates tend to occur in this way. Besides, electronic structures indicate that Al + Hf-terminated interfaces have stronger electronic interaction than that of Al-terminated ones and the Al-Hf bonds of Al + Hf-terminated interface with HCP stacking tend to covalent bonds, while Al–Al bonds of Al-terminated one are metal bonds. Al3Hf as enhanced heterogeneous nucleation of α-Al are effective from crystallography and thermodynamics.

Characterization of a strong covalent Th3+–Th3+ bond inside an Ih(7)-C80 fullerene cage

The nature of the actinide-actinide bonds is of fundamental importance to understand the electronic structure of the 5f elements. It has attracted considerable theoretical attention, but little is known experimentally as the synthesis of these chemical bonds remains extremely challenging. Herein, we report a strong covalent Th-Th bond formed between two rarely accessible Th3+ ions, stabilized inside a fullerene cage nanocontainer as Th2@Ih(7)-C80. This compound is synthesized using the arc-discharge method and fully characterized using several techniques. The single-crystal X-Ray diffraction analysis determines that the two Th atoms are separated by 3.816 Å. Both experimental and quantum-chemical results show that the two Th atoms have formal charges of +3 and confirm the presence of a strong covalent Th-Th bond inside Ih(7)-C80. Moreover, density functional theory and ab initio multireference calculations suggest that the overlap between the 7s/6d hybrid thorium orbitals is so large that the bond still exists at Th-Th separations larger than 6 Å. This work demonstrates the authenticity of covalent actinide metal-metal bonds in a stable compound and deepens our fundamental understanding of f element metal bonds.