Narrow Results

With Ti(OBu)₄ as precursor, and HAc as complexing agent, pure and W-doped TiO₂ gelatins were prepared by a sol-gel method. During the process of gel formation, metal ions were dispersed in the porous TiO₂ matrix. Then, powders of nano-TiO₂ and W-doped nano-TiO₂ were prepared by drying, grinding and heat treatment at different temperatures. The grain size and structure of the samples, pure TiO₂ and W-doped, and treated at different temperatures, were studied by X-ray diffraction (XRD), Beckman Coulter Sorption Analysis and TEM. Results showed that, with increasing temperature, the TiO₂ transformed from anatase to rutile and the grain size increased. This transformation and grain growth of TiO₂ could be retarded by doping with W.

Sulfur-doped SnO₂ nanoparticles with ultrafine sizes have been successfully prepared by a one-pot hydrothermal method. The obtained samples are characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), thermogravimetric (TG), analyzer UV-Vis spectroscopy, photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). The experimental results indicate that the doping level of sulfur element as well as the bandgaps of SnO₂ can be controlled to a certain extent by varying the amount of L-cysteine (L-cys). When evaluated as photocatalysts in the degradation of rhodamine B (RhB) and reduction of Cr(VI) under visible light region, the resultant sulfur-doped SnO₂ nanoparticles demonstrate obviously enhanced photocatalytic activities due to the markedly improved visible light response and effective separation of the photo-generated electron–hole pairs.

Multi-element doped porous carbon materials are considered as one of the most promising electrode materials for supercapacitors due to their large specific surface area, abundant mesoporous structure, heteroatom doping and good conductivity. Herein, we propose a very simple and effective strategy to prepare nitrogen, sulfur co-doped hierarchical porous carbons (N-S-HPC) by one-step pyrolysis strategy. The effect of sole dopants as a precursor was a major factor in the transformation process. The optimized N-S-HPC-2 possesses a typical hierarchically porous framework (micropores, mesopores and macropores) with a large specific surface area (1284.87m² g${}^{-1})$ and N (4.63 atomic %), S (0.53 atomic %) doping. As a result, the N-S-HPC-2 exhibits excellent charge storage capacity with a high gravimetric capacitance of 360F g${}^{-1}$ (1 A g${}^{-1})$ in three-electrode systems and 178F g${}^{-1}$ in two-electrode system and long-term cycling life with 87% retention after 10,000 cycles in KOH electrolyte.