Sulfur-doped Carbon Materials Research Articles

Pseudocapacitive contribution in sulfur-doped porous carbon nanosheets enables high-performance sodium-ion storage

Sulfur-doped carbon materials have sparked considerable attention as the anodes for sodium-ion batteries (SIBs) due to their relatively high reversible specific capacity and excellent pseudocapacitive effect. However, the content of sulfur dopants in carbon materials is usually limited and an efficient doping strategy is urgently imperative to date. Herein, a space-confined doping strategy is proposed to fabricate porous carbon nanosheets with high sulfur dopant content by using low-cost pitch as a precursor with the help of sodium thiosulfate (Na2S2O3). The thermostable nano-MgO used in this system can occupy the specific space during pitch decomposition to induce the formation of hierarchical carbon nanosheets. Interestingly, such a space-confinement effect of nano-MgO is able to enlarge the accessible contact area of reactants and inhibit the loss of sulfur from Na2S2O3, thus significantly increasing sulfur dopant content within carbon frameworks. The optimized sulfur-doped carbon nanosheets (S-PCNs-2) with a high sulfur content of about 20.56 wt% as anode for SIBs delivers an ultrahigh pseudocapacitive contribution of 92.55 % at 5 mV s−1 and thus enable a desirable specific capacity of 428.6 mAh g−1 at 0.1 A g−1 with a high initial Coulombic efficiency of 84.9 % and superior rate performance of 380.6 mAh g−1 at 5 A g−1. Furthermore, a long cycling lifespan with a capacity retention of 88 % after 1000 charge/discharge cycles can be achieved for the S-PCNs-2 anode. This work provides a simple yet efficient doping approach to fabricate carbon anodes with high heteroatom contents for SIBs.

High-efficiency sulfur-doped carbon photocatalysts synthesized by carbonization of lignosulfonate at low temperature

Heteroatom-doped carbon photocatalysts have attracted increasing attention since they are inexpensive, environmentally friendly, and highly efficient. Herein, sulfur-doped carbon photocatalysts were prepared by a one-step low-temperature carbonization method using sodium lignosulfonate (SLS) as a starting material. The physicochemical properties of the carbon photocatalysts were characterized by N 2 adsorption-desorption, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS), and so on. Compared with the carbon photocatalyst derived from alkali lignin, the sulfur-doped carbons from SLS can improve the degradation of tetracycline by nearly 40%. Sulfur species, i.e., sulfone and sulfoxide, can reduce the bandgap and promote the separation and transfer of photogenerated charge carriers under visible light irradiation. The recycling experimental results of S-C-N 2 -12 illustrate that the catalyst is stable without a remarkable loss in photocatalytic degradation of tetracycline after five successive runs, suggesting that the sulfur-containing species coordinated on the carbon surface are relatively stable. The results of radical-assisted electron spin resonance (ESR) and radical scavenger experiments show that h + plays a major role in the degrading of tetracycline. These findings suggest that the sulfur-doped carbon photocatalysts have a great potential in pollutant degradation and wastewater treatment. Sulfur-doped carbon materials were prepared by one-step low-temperature carbonization method using sodium lignosulfonate, then it is carried out with it as a catalyst for photocatalytic experiments to degrade tetracycline.

Nitrogen and Sulfur Doped Mesoporous Carbons, Prepared from Templating Silica, as Interesting Material for Supercapacitors

AbstractHighly accessible surface area and heteroatom‐doping are desired properties for carbon electrode materials to be used in electrochemical supercapacitors. In this paper, nitrogen and sulfur doped carbon materials with wide mesopores (13‐14 nm) were synthetized according to a hard template approach by pyrolysis of sucrose, 1,10‐phenanthroline or dibenzothiophene as carbon, nitrogen‐carbon or sulfur‐carbon precursors, respectively. The morphology and dimension of mesopores were induced by sacrificial SiO2 nanoparticles (10‐20 nm), which are removed at the end of synthesis by an etching solution to reveal a network of hemispherical pores. The interconnected pore structure was confirmed by scanning electron microscopy and transmission electron microscopy. X‐ray photoemission spectroscopy and elemental analysis confirmed the presence of nitrogen and sulfur functional groups. The prepared materials were fully characterized by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy in 0.5 M H2SO4. Notwithstanding the small surface (200 m2g‐1) determined by BET method, the nitrogen doped mesoporous carbon showed high specific gravimetric (∼170 F g‐1) and surface (∼835 F m‐2) capacitances that are comparable to those of materials with much higher surface area (5‐10‐fold higher).

Bio-sourced mesoporous carbon doped with heteroatoms (N,S) synthesised using one-step hydrothermal process for water remediation

Mesoporous carbon monoliths doped with nitrogen, sulphur or both have been prepared in one step hydrothermal carbonization from bio-based precursors. Glucose and pyrrole carboxaldehyde or glucose and thiophene carboxaldehyde aqueous solutions have been used as precursors for nitrogen and sulphur doped carbon materials, respectively. In the same hydrothermal process, a salt-templating approach was used to endow the material with mesoporosity. Additionally, the materials were also pyrolysed in N2 at 973 K. The average mesopore size of resulting xerogels is tuned by the used dopant. Both the doping and mesoporosity enhanced substantially the adsorption of large dye molecules. Accordingly, these metal-free, cost-effective and sustainable materials are excellent candidates for liquid phase environmental and energy applications where the dopant may play a role as catalytic active phase or electronic modulator.

Highly nanoporous carbon microflakes from discarded dental impression materials

Discarded dental alginate impression materials are used as carbon sources to prepare novel carbon microflakes via an industrially feasible pyrolysis–etching approach. Various characterizations reveal that the sulfur-doped carbon materials are porous layered-like microflakes with thicknesses of ~100–400nm. These microflakes have a high specific surface area of ~1000m2g−1, a large pore volume of 1.30cm3g−1 and a high mesoporosity of 95.6% without any activation, thereby making them promising for energy storage applications. Therefore, this study provides technological guidance in the use of discarded alginate impression materials to produce high-quality carbon materials.