Carbon Thermal Reduction Process Research Articles

Carbothermal synthesis of activated carbon-supported nano zero valent iron: effects of temperature, characterization, and reactivity

Activated carbon-supported nano zero valent iron was synthesized through a carbonthermal reduction process. Specifically, iron-impregnated activated carbon was thermally treated under N2 atmosphere at temperatures ranging from 350 to 1,150°C. Major properties of the synthesized materials were obtained through analysis of iron content, BET surface area, and pore size distribution. TEM images, X-ray diffraction (XRD), and Fourier transform infrared patterns were also obtained for characterization. Results show that zero valent iron was reduced from iron oxide and those nanoparticles were highly dispersed based on TEM images while XRD patterns indicate a progressive reduction of iron oxide to form elemental iron. Treatment temperature greatly impacted the characteristics of the carbonthermal products. The size of the particles, content of elemental iron, surface functional groups, and pore structure all changed with the change in treatment temperature. Synthesized materials were tested for their reactivities on chromate. Reduction of Cr(VI) by carbothermal products occurred based on analysis of Cr speciation. In addition, reduction ability differed with various carbothermal temperatures. Overall, materials synthesized at 550–750°C appears to stand out when chromate removal capability and removal rate are concerned.

Growth and Field Emission Properties of Cactus-like Gallium Oxide Nanostructures

Cactus-like −β-Ga2O3 nanostructures were synthesized by a simple carbon thermal reduction process. Cactus-like −β-Ga2O3 nanostructures are composed of a hollow microsphere and numerous −β-Ga2O3 nanowires grown from the surface. The structure and morphology of the as-synthesized Ga2O3 nanostructures were characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and selected area electron diffraction. The field emission properties of the products were investigated, and the turn-on fields of 12.6 V/μm and the threshold fields of 23.2 V/μm of the product are reported for the first time. The growth mechanism was proposed through observing the morphologies of different growth stages.

Oriented Bicrystalline GaN Nanowire Arrays suitable for Field Emission Applications

Oriented bicrystalline GaN nanowire arrays are synthesized by a catalytic carbon thermal reduction process. The bicrystalline structure is composed of (001) planes and the twin angle is 124°. Field‐emission measurements show that the oriented bicrystalline GaN nanowire arrays produce a current density of 10 μA/cm2 at a lower turn‐on fields of 8 V/μm. It suggests that the oriented bicrystalline GaN nanowire capped with catalyst particle arrays can serve as a promising candidate for field emission emitters.

Preparation and oxidation behavior of three-dimensional braided carbon fiber coated by SiC

In this paper, SiC coating on three-dimensional (3-D) braided carbon fiber was obtained, which was infiltrated with SiO 2 sol into 3-D braided carbon fiber and then carbon–thermal reduced. The effect of carbon–thermal reduction process was examined. Thermal–oxidative stability of the 3-D braided carbon fiber coated with SiC was compared with original 3-D braided carbon fiber. The oxidation stability of the SiC coating/3-D braided carbon fiber was extended up to 900–1000 °C. After exposure to air at 900–1000 °C , the residual weight of the composite was 26–30%.