Carbothermal conversion of boric acid into boron-oxy-carbide nanostructures for high-power supercapacitors

In this study, we report a facile carbothermal method for the preparation of boron-oxy-carbide (BOC) nanostructures and explore their properties towards electrochemical energy storage devices.

Formation Mechanism and Properties of Foam-Structured ZnO Films Prepared Using Catalyst-Free Carbothermal Method

Foam-structured ZnO films were formed on c-axis Al2O3 substrates by using a catalyst-free carbothermal method. The morphological properties of the films strongly depended on their substrate position in the reactor, implying that the quantity of Zn vapor transported played a crucial role in determining the film structure. The formation mechanism of the films is proposed to be as follows: with increased transport of Zn vapor, vaporized Zn elements transformed into liquid Zn nanoparticles, and the liquid Zn elements on the rods promoted the new nucleation of ZnO nanorods. The repeated growth of ZnO rods at the nucleation sites led to the foam-like structure. The as-formed foam-structured ZnO films exhibited the wurtzite crystal structure, and the atomic composition ratio of Zn to O was 1 : 0.85. The main photoluminescence emissions were centered at 3.3 and 2.5 eV, and they were attributed to band-to-band and defect-related transitions, respectively.

Synthesis of Si-Based Refractory Compounds from Coconut Shell by Carbothermal Method

The synthesis of Si-based refractory compounds from coconut shells (CS) by carbothermal treatment was investigated. Coconut shells, an agro-waste was utilised in the processing of the Si-based refractory compounds in a single stage carbothermal processing route. The treatment scheduled was carried out in a conventional heat treatment furnace at a temperature window of (900-1900 °C) at 10 °C/min heating rate in a controlled atmosphere. X-ray Diffractometer (XRD) was used to analyzed and quantify the crystalline and amorphous phases in the reaction products. The results from Fourier transform infrared spectroscopy (FTIR) revealed that, the dominant functional groups present after the carbothermal treatment were mainly Si-O-Si and Si-C groups. Also, the XRD results showed that the polytypes are mainly of α-SiC type precipitating as hexagonal symmetry of 6H-SiC and 4H-SiC type. The silica polytypes amount to about 8-14 wt.% of the silica polytypes as observed for different processing temperatures adopted. However, the total yield of SiC-made up between 11 to 40 wt.% of the crystalline phases as identified by XRD from the process. It is evident that the adoption of this processing route is a viable option for the synthesis of coconut shells as potential reinforcement for composites design.