Search

Hierarchical porous carbon materials (HPC) derived from coal tar pitch are synthesized through a one-step carbonization and activation method using CaO as the hard template. The influence of activator dosage, activation time and temperature on the morphology, pore structure and supercapacitor performances has been systematically researched. The synthesized carbon materials are characterized using scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, the Brunauer–Emmett–Teller method and X-ray photoelectron spectroscopy. The as-prepared HPC samples consist of irregular dense carbon blocks. The optimal HPCs-0.5-600-2 possesses a large surface area (1388.62 m2 g−1) with a hierarchical pore structure and moderate heteroatom content. The HPCs-0.5-600-2 electrode manifested a high specific capacitance of 329 F g−1 at a current density of 1 A g−1 and a good rate capability (71.4% retention at 50 A g−1) in the three electrode system. The symmetric supercapacitor assembled with HPCs-0.5-700-2 electrodes delivers an energy density of 6.45 W h kg−1 and a power density of 483.7 W kg−1, and also shows a cycle life with a capacitance retention rate of 56.9% at 10 A g−1 after 4000 cycles. [ABSTRACT FROM AUTHOR]

A high concentration gel polymer electrolyte (GPE) was prepared by simply using LiFSI–LiNO3 dissolved in 1,3-dioxolane. The Li‖Li cell achieves stable battery cycling for over 3200 h. Furthermore, the Li‖Cu cell demonstrates a high CE of 99.2%. Even at a high current density of 8 mA cm−2, a high CE of 98.5% was still achieved. Notably, in a Li‖LiFePO4 cell, this electrolyte enables high capacity retention of 94.5% and an average CE of 99.8% over 500 cycles, showing promising prospects for high-performance lithium metal batteries. [ABSTRACT FROM AUTHOR]

The selective depolymerization of PET plastics to p-xylene (xylene) is very challenging owing to the full deoxygenation of the terephthalic acid monomer and the retainment of the benzene ring through saturation. In this study, the modification of Co–Al catalysts by introducing a second metal (Fe, Cu, Ni, or Zn) was conducted to tailor the activity of the cobalt species for the conversion of PET to xylene. The results indicated that the CoFe alloy in the Co–Fe–Al catalyst weakened the adsorption/activation of H2, achieving xylene yields of >99.0% from PET. Co–Fe–Al suppressed the ring hydrogenation of the benzene ring, while Co–Al and Co–Ni–Al catalyzed the hydrogenation of the benzene ring and cleavage of the C–C bond in the intermediates. Benzene ring-containing intermediates showed a high affinity for Co–Ni–Al and Co–Al, facilitating their hydrogenation. Co–Fe–Al could preferably adsorb and activate the oxygen-containing functionalities of the intermediates for the deoxygenation reactions. The hydrogenolysis reaction of C–OH in intermediates, like 1,4-benzenedimethanol (Ea: 137.8 kJ mol−1), was the rate-determining step, while the hydrogenation of the carboxylic intermediates was much easier. [ABSTRACT FROM AUTHOR]