N-Doped Yolk–Shell Carbon Nanospheres with “Carbon Bridges” for Supercapacitors

Abstract

N-doping multilocular carbon spheres are beneficial to improving the electrical property due to their unique pore structure and elemental composition; nevertheless, there is a great challenge to fabricate this structure in a facile way. In this work, an N-doping yolk–shell carbon nanosphere with a “carbon bridges” structure was prepared by domain-limited carbonization of RF@SiO2 (RF = resorcinol-formaldehyde resin) with ethylenediamine (EDA) as the nitrogen precursor. The structure of the “carbon bridges” and the carbon shell’s thickness can be adjusted by controlling the thickness of the silica layer, resulting in a change in morphology (from dense nanospheres to yolk–shell nanospheres). The optimized yolk–shell carbon nanospheres (C@C-2 nanospheres) exhibited high N-doping, an abundant micro-mesoporous structure, and an optimum “carbon bridges” structure, contributing to a high-rate capability in a supercapacitor, which was reflected in the energy storage dynamics. Herein, C@C-2 nanospheres, as an electrode material for supercapacitors, presented a reversible specific capacitance of 373.3 F g–1 at 0.5 A g–1 in 2 M KOH and retained a well-advanced capacitance retention capability (95.8%) at 4 A g–1 for more than 10,000 cycles. This work sheds light on an avenue to design high-performance porous carbons for efficient energy storage.

Electron-Rich Ru Supported on N-Doped Coffee Biochar for Selective Reductive Amination of Furfural to Furfurylamine

“…The area percentages of pyrrolic N (from 34.5 to 18.2%) and pyridinic N (from 29.3 to 26.2%) on Ru/NCB-600 decreased compared with Ru/CB-600, and the decrease of pyrrolic N and pyridinic N can be attributed to the formation of Ru–N species (19.6%), both of which can be preferentially paired with metal ions (Table S3). Compared with Ru/CB-600, the peaks of pyridinic N and pyrrolic N on Ru/NCB-600 shift to higher binding energy, suggesting that there exists an electron transfer from N to Ru. Figure d shows that the binding energy of Ru 3d 5/2 on Ru/NCB-600 moved from 280.3 to 280.2 eV compared with Ru/CB-600 (Figure b), demonstrating that N doping could increase the local electron density of Ru species (Ru δ− ).…”

Cobalt‐based zeolitic imidazole framework derived hollow Co3S4 nanopolyhedrons for supercapacitors

“…The search for high energy density and low-cost electrode materials for pseudocapacitors is a top priority. [1][2][3][4][5][6] Compared with oxides, transition metal compounds have better thermal stability and higher conductivity. They have attracted much attention as potential supercapacitor electrode materials.…”