One-step route to a hybrid TiO₂/Ti_xW_1−xN nanocomposite byin situselective carbothermal nitridation

Abstract

Metal oxide/nitride nanocomposites have many existing and potential applications, e.g. in energy conversion or ammonia synthesis. Here, a hybrid oxide/nitride nanocomposite (anatase/Ti x W 1−x N) was synthesized by an ammonia-free sol-gel route. Synchrotron x-ray diffraction, complemented with electron microscopy and thermogravimetric analysis, was used to study the structure, composition and mechanism of formation of the nanocomposite. The nanocomposite contained nanoparticles (<5 nm diameter) of two highly intermixed phases. This was found to arise from controlled nucleation and growth of a single oxide intermediate from the gel precursor, followed by phase separation and in situ selective carbothermal nitridation. Depending on the preparation conditions, the composition varied from anatase/Ti x W 1−x N at low W content to an isostructural mixture of Ti-rich and W-rich Ti x W 1−x N at high W content. In situ selective carbothermal nitridation offers a facile route to the synthesis of nitride-oxide nanocomposites. This conceptually new approach is a significant advance from previous methods, which generally require ammonolysis of a pre-synthesized oxide.

Doped-carbon electrocatalysts with trimodal porosity from a homogeneous polypeptide gel

“…The only example of the evolution of separate phases from a sol gel achieved just partial phase separation. 32 This has wide implications, since metal carbides are emerging as important catalysts, 33 particularly in the eld of noble-metal replacement. This integration of multiple desirable features such as multimodal porosity or diverse functionality into a single material enables ne-tuning and optimization of the material properties.…”

Nano-mechanical characterization of plasma surface tungstenized layer by depth-sensing nano-indentation measurement

“…When high tungsten content at the surface of the alloyed layer leads to W-rich Ti x W 1−x phase. As the tungsten content gradually decreases, Ti-rich Ti x W 1−x phase predominates and this shift is coupled with a substantial strengthening of the tungsten [27].…”

Iron-catalyzed graphitization of biomass

“…Therefore by choosing an intermediate temperature it is possible to achieve selective carbothermal reduction of one metal while leaving the other one as an oxide. 21 Metal oxide/graphitic carbon nanostructures are investigated in a wide range of applications from supercapacitors and batteries, 22 to water treatment. 23 The proof of concept of making mesoporous graphitic nanotubes alongside metal oxide nanoparticles in a single step therefore offers a promising future route to synthesizing functional materials for many technologies.…”