Nitrogen-Doped Titanium Dioxide for Selective Photocatalytic Oxidation of Methane to Oxygenates

Photocatalytic conversion of methane (CH4) to value-added chemicals using H2O as the oxidant under mild conditions is a desired sustainable pathway for synthesizing commodity chemicals. However, controlling product selectivity while maintaining high product yields is greatly challenging. Herein, we develop a highly efficient strategy, based on the precise control of the types of nitrogen dopants, and the design of photocatalysts, to achieve high selectivity and productivity of oxygenates via CH4 photocatalytic conversion. The primary product (methanol) is obtained in a high yield of 159.8 μmol·g-1·h-1 and 47.7% selectivity, and the selectivity of oxygenate compounds reached 92.5%. The unique hollow porous structure and substituted nitrogen sites of nitrogen-doped TiO2 synergistically promote its photo-oxidation performance. Furthermore, in situ attenuated total reflectance Fourier transform infrared spectroscopy provides direct evidence of the key intermediates and their evolution for producing methanol and multicarbon oxygenates. This study provides insights into the mechanism of photocatalytic CH4 conversion.

Electrochemically dealloyed nanoporous Fe40Ni20Co20P15C5 metallic glass for efficient and stable electrocatalytic hydrogen and oxygen generation

The anion exchange membrane (AEM) in fuel cells requires new, stable, and improved electrocatalysts for large scale commercial production of hydrogen fuel for efficient energy conversion. Fe40Ni20Co20P15C5, a novel metallic glass ribbon, was prepared by arc melting and melt spinning method. The metallic glass was evaluated as an efficient electrocatalyst in water-splitting reactions, namely hydrogen evolution reaction under acidic and alkaline conditions. In addition, oxygen evolution reaction in alkaline medium was also evaluated. In 0.5 M H2SO4, the metallic glass ribbons, after electrochemical dealloying, needed an overpotential of 128 mV for hydrogen evolution reaction, while in 1 M KOH they needed an overpotential of 236 mV for hydrogen evolution. For the oxygen evolution reaction, the overpotential was 278 mV. The electrochemical dealloying procedure significantly reduced the overpotential, and the overpotential remained constant over 20 hours of test conditions under acidic and alkaline conditions. The improved electrocatalytic activity was explained based on the metastable nature of metallic glass and the synergistic effect of metal hydroxo species and phosphates. Based on the excellent properties and free-standing nature of these metallic glass ribbons in electrolyte medium, we propose the current metallic glass for commercial, industrial electrocatalytic applications.

The growth behavior of columnar grains in a TiAl alloy during directional induction heat treatments

In the process of DHT, the curving grain boundary will move towards curvature center of grain under the action of interface tension.

One-dimensional zirconium-doped titanate nanostructures for rapid and capacitive removal of multiple heavy metal ions from water

A novel, one-dimensional zirconium-doped titanate with a porous core and a textured surface of ultrafine nanofibers, exhibiting superior efficiency for rapid and simultaneous removal of multiple heavy metal ions.

Synthesis and Functions of Ag2S Nanostructures

The paper presents a review about synthesis and applications of Ag2S nanostructures. As the modern photoelectric and biological materials, Ag2S nanomaterials are potentially useful for both structure and function purposes. Ag2S is a direction narrow band gap semiconductor with special properties. Ag2S nanostructures have been widely researched in chemistry and biochemistry fields because of their unusual optical, electrical, and mechanical properties. It can also be used in many fields, such as photovoltaic cells and infrared detector. In the past few years, Ag2S nanostructures have been synthesized by various methods. The article mainly discusses the four types of preparation methods. Moreover, this article shows a detailed review on the new properties, fabrication, and applications of Ag2S nanocrystals.

Review of one-dimensional and two-dimensional nanostructured materials for hydrogen generation

Hydrogen is an attractive alternative to fossil fuels in terms of environmental and other advantages.

Nanosized metal oxide and nanobelts prepared by selective dealloying of Ti-based amorphous powders

Two typical nanomaterials, nanosized metal oxides and nanobelts, are obtained in one-pot selective dealloying process by using multiple-component Ti-based amorphous powders as dealloying precursors. The microstructure and photoelectric conversion property of the as-synthesized Zr-doped nanobelts are comprehensively investigated. Particularly, a core-shell structure, for example, residual amorphous alloy as the microsized core and nanosized metal oxide composites (mainly TiO2 and CuO) as the shell, forms as a byproduct of the selective dealloying. These resultant metal oxide composites show large specific surface area, and superior adsorption efficiency and capacity for removing toxic Cr(6+) in aqueous solution. The differences in the standard electrode potentials between the multiple-component elements in amorphous powders trigger their selective dealloying in alkaline solutions.