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Structural trends, such as the migration of Sn/In to surface layers, are observed on melting Ga–Sn/Ga–In alloys.

Liquid GaAu systems provide the possibility of developing dynamic and self-healing materials for a variety of applications, including catalysis. GaAu systems provide both dynamic capability by being liquid at just above room temperature, as a result of the Ga, and likely catalytic activity, resulting from the Au. While the formation of a Ga

It is well-understood that during the liquid-to-solid phase transition of alloys, elements segregate in the bulk phase with the formation of microstructures. In contrast, we show here that in a Bi–Ga alloy system, highly ordered nanopatterns emerge preferentially at the alloy surfaces during solidification. We observed a variety of transition, hybrid and crystal-defect-like patterns, in addition to lamellar and rod-like structures. Combining experiments and molecular dynamics simulations, we investigated the influence of the superficial Bi and Ga2O3 layers during surface solidification and elucidated the pattern-formation mechanisms, which involve surface-catalysed heterogeneous nucleation. We further demonstrated the dynamic nature and robustness of the phenomenon under different solidification conditions and for various alloy systems. The surface patterns we observed enable high-spatial-resolution nanoscale-infrared and surface-enhanced Raman mapping, which reveal promising potential for surface- and nanoscale-based applications. During a liquid-to-solid phase transition, a Bi–Ga alloy forms ordered nanostructured patterns on its surface.

Experiment has shown that dilute GaBi systems produce a range of self-organised nanostructured patterns at the surface [Tang et al., Nat. Nanotechnol., 2021, 16, 431-439]. Using extensive ab initio molecular dynamics simulations, we elucidate the mechanisms underlying the formation of the Bi surface islands in Bi-doped Ga liquid metals. Here, we show that in order for internal Bi atoms to diffuse to the surface a lateral extension of the Ga surface network is required. Furthermore, the absence of surface Bi patterning perturbs the Ga surface network providing a preferred path for an internal Bi to diffuse. By understanding how and why Bi nucleates at a surface, we increase the ability to control, manipulate and design such systems for use in future electronic devices.

Using ab initio molecular dynamics, we show that a recently discovered form of 2D Ga—gallenene—exhibits highly variable thickness dependent properties. Here, 2D Ga of four, five and six atomic layers thick are found to be thermally stable to 457 K, 350 K and 433 K, respectively; all well above that of bulk Ga. Analysis of the liquid structure of 2D Ga shows a thickness dependent ordering both parallel and perpendicular to the Ga/vacuum interface. Furthermore, ground state optimisations of 2D Ga to 12 atomic layers thick shows a return to a bulk-like bonding structure at 10 atoms thick, therefore we anticipate that up to this thickness 2D Ga structures will each exhibit novel properties as discrete 2D materials. Gallenene has exciting potential applications in plasmonics, sensors and electrical contacts however, for the potential of 2D Ga to be fully realised an in depth understanding of its thickness dependent properties is required.

Catalysts are required to ensure electrochemical reduction of CO

Catalysts are required to ensure electrochemical reduction of CO2 to fuels proceeds at industrially acceptable rates and yields. As such, highly active and selective catalysts must be developed. Herein, a density functional theory study of p-block element and noble metal doped graphene-based single-atom catalysts in two defect sites for the electrochemical reduction of CO2 to CO and HCOOH is systematically undertaken. It is found that on all of the systems considered, the thermodynamic product is HCOOH. Pb/C3, Pb/N4 and Sn/C3 are identified as having the lowest overpotential for HCOOH production while Al/C3, Al/N4, Au/C3 and Ga/C3 are identified as having the potential to form higher order products due to the strength of binding of adsorbed HCOOH.

Single-atom catalysts are promising candidates for many industrial reactions. However, making true single-atom catalysts is an experimental dilemma, due to the difficulty of keeping dopant single atoms stable at temperature and under pressure. This difficulty can lead to clustering of the metal dopant atoms in defect sites. However, the electronic and geometric structure of sub-nanoscale clusters in single-atom defects has not yet been explored. Furthermore, recent studies have proven sub-nanoscale clusters of dopants in single-atom defect sites can be equally good or better catalysts than their single-atom counterparts. Here, a comprehensive DFT study is undertaken to determine the geometric and electronic structure effects that influence clustering of noble and p-block dopants in C

Density functional theory calculations have been used to calculate activation barriers for N2 dissociation on a range of possible active sites on ruthenium (Ru) nanoparticles, including step, edge,...

Using

It is well-understood that during the liquid-to-solid phase transition of alloys, elements segregate in the bulk phase with the formation of microstructures. In contrast, we show here that in a Bi-Ga alloy system, highly ordered nanopatterns emerge preferentially at the alloy surfaces during solidification. We observed a variety of transition, hybrid and crystal-defect-like patterns, in addition to lamellar and rod-like structures. Combining experiments and molecular dynamics simulations, we investigated the influence of the superficial Bi and Ga

A combined experimental and computational study is reported on a hitherto unrecognised single lanthanide catalyst for the breaking of molecular nitrogen and formation of ammonia at ambient temperature and low pressure.We combine in situ electrical conductance and electron diffraction measurements to track the conversion from the lanthanide metals to the insulating lanthanide nitrides.The efficiency of the conversion is then interpreted using DFT+U calculations, suggesting a molecular nitrogen dissociation pathway separate from that well-established for transition metals.Finally, we show that exposure of the lanthanide surfaces to both molecular nitrogen and hydrogen results in the formation of ammonia.