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Multifunctional electrocatalysts are desirable for overall water splitting and zinc-air batteries. In this work, N, S co-doped carbon nanotubes (CNT-NS) with a plentiful of defects were obtained through a novel molecular-level codoped and lattice defect construction method. Thiamine hydrochloride and thiocarbamide were adopted as new precursors in situ doping N and S into multi-walled CNTs surfaces, and lattice defects were constructed by in situ chemical etching using ammonium chloride and ammonium bicarbonate. These surface defects and N,S biatom co-doping synergistic effects can accumulate the CNT-NS to exhibit the superior behavior for electrocatalysis of water splitting and zinc-air batteries. The overpotential for overall water splitting was 1.61 V and the specific capacity for zinc-air batteries was 781 mA h g−1, which was superior to previous works. According to the Operando Raman spectroscopy measurements, the S atoms can serve as the intrinsic catalytic sites for HER and OER, and the defective CNT structures could enhance the catalytic kinetics by the electron-transfer process. Further, density functional theory (DFT) results also indicated the contribution of binary atoms co-doping for low ΔG H∗ values. Therefore, this work provides the valuable reference for rational design/construction for metal-free catalysts of overall water splitting. [Display omitted] • CNT-550-NS were successfully prepared through a molecular-level codoped and lattice defect construction method. • CNT-550-NS exhibited a plentiful of defective structure on the carbon nanotubes surfaces. • CNT-550-NS possessed a high contents of heteroatoms of N and S. • CNT-550-NS executed a remarkable performance for HER, OER and ORR. [ABSTRACT FROM AUTHOR]

Improving the specific capacitance of carbon aerogels in supercapacitors and maintaining their high specific surface area remained an important challenge. Here, we prepared resorcinol-phloroglucinol-formaldehyde carbon aerogels reduced with hydrazine hydrate by a microwave method. The effects of the amount of hydrazine hydrate and the time of microwave reaction on the electrochemical performance of carbon aerogels were investigated. The reductive carbon aerogels were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The XPS spectra of reductive carbon aerogels indicated a presence of four nitrogen N1s groups, three oxygen O1s groups and six carbon C1s groups in the deconvoluted spectra. Surface area analysis and electrochemical performance were also investigated. The results showed that the specific surface area of the N-doped carbon aerogels could be as high as 803 m2 g−1. According to the electrochemical testing results, the specific capacitance of the N-doped carbon aerogels significantly increased and reached 219 F g−1 at a current density of 1.5 A g−1 compared to the pristine carbon aerogels. The optimal dosage and time of hydrazine hydrate was 20.6 mol L−1 for 25 min. The N-doped carbon aerogels electrode exhibited excellent reversibility with a cycling efficiency of 93.6% after 10000 cycles. [ABSTRACT FROM AUTHOR]

A novel, carbon-doped graphitic carbon nitride (C C 3 N 4 -20) was used for methylene blue (MB) removal from an aqueous solution. In dye adsorption experiments, C C 3 N 4 -20 showed a high MB adsorption efficiency due to its extended π-conjugation system and porous structure, the maximum adsorption capacity of C C 3 N 4 -20 for MB was 57.87 mg g −1 , when the initial concentrations of MB were 20 mg L −1 . A Langmuir model fit the MB adsorption isotherm of C C 3 N 4 -20, and a pseudo-second-order kinetic model fit the adsorption kinetics. The MB adsorption process on C C 3 N 4 -20 is physical and mainly via electrostatic attraction and π–π interactions. [ABSTRACT FROM AUTHOR]

The influence of metals on the structure and performance of carbon aerogels is presented here. Metal-doped carbon aerogels (M-CA) were obtained by a simple in situ method without any catalyst. The physical properties were characterized by SEM, XRD, Raman spectroscopy, XPS, and N 2 adsorption-desorption. The results show that the addition of metal particles did not destroy the original 3D structure of carbon aerogels, and Ni-CA displayed excellent pore size distribution and a high degree of graphitization. The results of the electrochemical performance revealed nickel doped carbon aerogel (Ni-CA) gave the highest specific capacitance (126.6 F g − 1 ) at 1 A g − 1 because of the suitable pore size distribution and high conductivity. A cycling performance test showed good cycle stability of all the M-CA in this study, and the attenuation of Ni-CA after 1000 cycles was the lowest recorded, at only 0.6%. [ABSTRACT FROM AUTHOR]

The hierarchical porous nitrogen-doped two-dimensional carbon (HNGC) was prepared by simple calcination of magnesium sulfate (MgSO 4) and self-synthesized nitrogen-doped two-dimensional graphene-like carbon at a mild temperature in oxygen. The influence MgSO4 on the morphology, structure and chemical composition of the prepared HNGC samples were studied using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, surface area analysis, X-ray photoelectron microscopy and elemental analyzer. HNGC-2 exhibited a uniform three-dimensional coral-like porous inter-connected structure, large specific surface area, high pore volume, and no loss of nitrogen content. HNGC-2 demonstrated an excellent rate capability of 62.8% at 20 A g−1, outstanding stability of 96.1% following 5000 cycles and the assembled symmetric supercapcitor achieved 12.5 Wh kg−1 at a 350 Wkg-1 and 7.5 Wh kg−1 at 3500 Wkg-1. The novel method was also found to be effective for facilitating the electrochemical performance of commercial biomass active carbon. In addition, HNGC-2 was used for the photo-catalytic degradation of methylene blue and over 99% of methylene blue was successfully degraded under 25-min visible irradiation in the presence of potassium persulfate. The enhanced electrochemical performance and the excellent photo-catalytic performance of HNGC-2 indicated that porous carbon can be successfully activated using an appropriate oxidation strategy. The illustration for the formation of the hierarchy porous structure of HNGC materials. [Display omitted] • Hierarchical porous nitrogen-doped carbon was prepared by a novel strategy. • The influence of Magnesium sulfate was systematically studied and discussed. • The strategy can greatly enhance the photo-catalytic and electrical performance. [ABSTRACT FROM AUTHOR]