Lamellar Hierarchical Porous Carbon Prepared from Coal Tar Pitch through a Lamellar Hard Template Combined with the Precarbonization and Activation Method for Supercapacitors

The lamellar porous carbon favors the diffusion and penetration of electrolyte ions and presents a fantastic advantage as an energy storage electrode material. In this work, the lamellar Mg5(OH)4(CO3)2·4H2O template is synthesized via a simple precipitation method in the low-temperature hydrothermal condition. Lamellar hierarchical porous carbon (LHPC) is successfully synthesized through the Mg5(OH)4(CO3)2·4H2O hard template and the KOH activation method using coal tar pitch (CTP) as the carbon source. The effects of activation temperature and activator dosage on the morphology, microstructure, and supercapacitor performance are researched at length. LHPCs-1–700 displays a good lamellar structure and an abundant mesoporous structure, so as to exhibit superior capacitive performance compared with other carbon electrodes. The specific capacitance for LHPCs-1–700 reaches 298 F g–1 at 1 A g–1 and still maintains 234 F g–1 at 50 A g–1 with a high capacitance retention of 78.5% in the three-electrode system. The kinetic behavior of the LHPCs-1–700 electrode was also analyzed according to the CV data obtained at different scan rates, and it was found that the fast kinetic capacitance contribution was up to 87% at 200 mV s–1. The assembled LHPCs-1–700 symmetric supercapacitor delivered an energy density of 16.73 W h kg–1 with a power density of 859.4 W kg–1 in 1 M Na2SO4 solution. Besides, the specific capacitance retention rate could still reach 95.8% after 8000 cycles

In Situ Ti³⁺/N-Codoped Three-Dimensional (3D) Urchinlike Black TiO₂ Architectures as Efficient Visible-Light-Driven Photocatalysts

In situ Ti³⁺/N-codoped 3D urchinlike black TiO₂ (b-N-TiO₂) is synthesized via hydrothermal treatment with an in situ solid-state chemical reduction method, followed by annealing at 350 °C in argon. The results indicate that N and Ti³⁺ was codoped into the lattice of anatase TiO₂. The prepared b-N-TiO₂, with a narrow bandgap of ∼2.43 eV, possesses a three-dimensional (3D) urchinlike nanostructure, which is composed of fiberlike architecture with a length of 200–400 nm and a width of 25 nm. The visible-light-driven photocatalytic degradation rate of Methyl Orange and hydrogen evolution rate for b-N-TiO₂ are 95.2% and 178 μmol h^–1 g^–1, respectively, which are ∼3 and ∼8 times higher than those of pristine TiO₂. The excellent photocatalytic activity is mainly attributed to synergistic effect of the N and Ti³⁺ codoping narrowing the bandgap, and unique 3D urchinlike architecture favors the separation and transport of photogenerated charge carriers and offers more surface-active sites