Controllable synthesis of Mo2C with different morphology and application to electrocatalytic hydrogen evolution reaction

In order to evaluate the effect of precursors and synthesis strategies on catalytic ability of Mo2C in the hydrogen evolution reaction (HER), four kinds of Mo2C were synthesized using two kinds of MoO3 by two strategies. Compared with the one-step direct carbonization strategy, Mo2C with a large special surface area and a better performance could be synthesized by the two-step strategy composed of a nitridation reaction and a carbonization reaction. Additionally, the as-prepared porous Mo2C nanobelts (NBs) exhibit good electrocatalytic performance with a small overpotential of 165 mV (0.5 M H2SO4) and 124 mV (1 M KOH) at 10 mA cm-2, as well as a Tafel slope of 58 mV dec-1 (0.5 M H2SO4) and 59 mV dec-1 (1 M KOH). The excellent catalytic activity is ascribed to the nano crystallites and porous structure. What’s more, the belt structure also facilitates the charge transport in the materials during the electrocatalytic HER process. Therefore, the two-step strategy provides a new insight into the structural design with superior performance for electrocatalytic HER.

Room-temperature printing of 2D GaN semiconductor via liquid metal gallium surface confined nitridation reaction

Outstanding wide-bandgap semiconductor materials like gallium nitride (GaN) have been extensively utilized in power electronics, radiofrequency power amplifiers, and harsh environment adaptability. Due to its quantum confinement impact in enabling desired deep-ultraviolet emission, excitonic impact, and electronic transport features, two-dimensional (2D) GaN has been one of the most remarkable areas for the future growth of microelectronic devices. Here, for the first time, we report a large area, wide bandgap, and room-temperature 2D GaN synthesis and printing strategy via liquid metal gallium surface-confined nitridation reaction. The developed low-temperature synthesis and printing process is consistent with various electronic device manufacturing methods and thus opens a way for the cost-effective growth of the third-generation semiconductor. In particular, the fully printed field-effect transistors relying on the GaN show p-type switching with an on/off ratio greater than 105, maximum field-effect hole mobility of 53 cm2 V−1 s−1, and a small sub-threshold swing at room temperature. The current study establishes a room temperature way to produce the GaN, which can be further verified, generalized, and realized for various upcoming electronic and photoelectronic applications.

Influence of the Feed Powder Composition in Mechanical Properties of AlN-Nano-Reinforced Aluminium Composites Coatings Deposited by Reactive Direct Laser Deposition

Aluminium matrix composite coatings reinforced with AlN nanopaticles have been manufactured by direct laser deposition on an AA6082 alloy substrate. The reinforcement of the composite has been generated by the direct nitridation reaction of the feed powder with the carrier gas (N2) heated by an HPDL beam during the fabrication of the coating. The coating obtained consists of nano-sized AlN particles in an aluminium matrix, and the crystalline structure of the obtained AlN depends on the characteristics of the powder used. In this work, the influence of the feed powder composition is studied by comparison among pure aluminium, Al12-Si alloy, and AA6061 alloy, on the formation of AlN and its crystalline structure. A correlation was established between the temperature distribution reached by the particles, their composition, and the nitridation reaction mechanisms. The effect of the reinforcement was evaluated by comparing the microstructure and mechanical properties (microhardness, nanoindentation) of the composite costing with non-reinforced Al coatings and uncoated AA6082. Al/AlN composite coatings with improved properties were achieved, reaching hardness values that were 65% higher than coatings without reinforcement.

Enhanced photoelectrochemical water-splitting performance of SrNbO2N photoanodes using flux-assisted synthesis method and surface defect management

Particle-assembled SrNbO2N photoanodes were obtained using flux-assisted nitridation reaction. The optimal experimental parameters were studied for SrNbO2N particles with minimum surface defects and high crystallinity.

The preparation of Ni/Mo-based ternary electrocatalysts by the self-propagating initiated nitridation reaction and their application for efficient hydrogen production

This work introduces a novel strategy via the in situ thermal decomposition initiated nitridation reaction for synthesizing Ni/Mo-based ternary HER electrocatalysts.

Red-emission over a wide range of wavelengths at various temperatures from tetragonal BaCN2:Eu2+

A new tetragonal BaCN2 polymorph was obtained via a simple nitridation reaction of BaCO2, and the Eu doped product showed a red emission with an extremely wide range of red-shift of the emission wavelength with decreasing temperature.