Sulfur-doped Carbons Research Articles

Biomass-derived sulfur-doped porous carbon for CO2 and CH4 selective adsorption

Series of sulfur-doped porous carbons were prepared by using glucose as carbon source and sodium dodecyl sulfate as sulfur source to synthesize sulfur-based carbon precursor and KOH as activator. Pore structure parameters and sulfur content of the prepared carbon materials could be facility regulated by controlling the ratio of KOH/sulfur-based carbon precursor and activation temperature, and their adsorptive separation properties towards CO2 and CH4 were investigated. Results showed that the higher the ultra-microporous volume and the S content of the prepared sulfur-doped porous carbon were, the larger the CO2 and the CH4 adsorption capacity were. The maximum adsorption capacity of CO2 (6.54 mmol/g, 273.15 K and 101 kPa, hereinafter) and CH4 (2.98 mmol/g), and the excellent selectivity of CO2/N2 (75.7) and CH4/N2 (22.8) were achieved by ACS-700-2 because of its higher ultra-microporous pore volume and the highest S content. Permeation experiment, cycle stability test and adsorption thermodynamics experiment show that the prepared S-doped porous carbon had good application potential in the separation and enrichment of CO2 in flue gas and CH4 in coalbed methane. In addition, the pore formation mechanism of sulfur-doped porous carbon was discussed.

Preparation of inexpensive S-doped porous carbons for high-performance supercapacitors

Low-cost sulfur-doped porous carbons were prepared through hard template method by using inexpensive colloidal SiO2 nanoparticles as template, glucose as carbon source, H2SO4 as pre‑carbonized reagent and sulfur source. The effects of H2SO4 and carbonization temperature on the microscopic morphology, the pore structure and the specific surface area of porous carbons were explored through multiple characterization methods. The capacitive performance of porous carbons was investigated by multiple electrochemical methods. It was found that the pore structure, specific surface area and the content of sulfur element of carbon are highly dependent on the carbonization temperature. The sulfur-doped porous carbon SPC-900 has much larger surface area and larger pore volume, and thus much better capacitive performance than un-doped PC-900, indicating that H2SO4 can increase the surface area and the pore volume during the preparation process. SPC-900 offers the advantages of lower cost, larger pore size, higher pore volume, better capacitive performance and better rate performance compared to expensive mesoporous carbon CMK-3. In the three-electrode system, the specific capacitance of SPC-900 can reach 363 F g−1, whereas that of PC-900 is only 164 F g−1 at a current density of 0.5 A g−1. The double layer capacitance (EDLC) and pseudocapacitance can both be increased by the sulfur element, according to the capacitive contribution study. Additionally, the SPC-900 can maintain its initial specific capacitance of 98.1 % for 10,000 cycles at a current density of 0.5 A g−1, demonstrating both its high cycling performance and potential for practical applications.

Facile preparation of heteroatom S doped dumbbell-like hard carbon for boosting potassium-ion storage capability

Potassium-ion storage devices have gained increasing interest in applications such as large-scale energy storage and smart grids due to the advantages of high abundance, low cost, high working voltage, and fast charge transport in electrolytes. However, obtaining high-performance anodes with excellent rate performance and cycling stability remains a challenge due to the much larger size of K+ ions. In this contribution, heteroatom S doped dumbbell-like hard carbon (SDHC) are synthesized using sucrose as the carbon source. SDHC-700, which is carbonized at 700 °C, exhibits the highest sulfur doping degree (9.3 at.%), remarkable reversible capacity (416 mAh g-1 at 0.05 A g-1), and superb rate performance (174 mAh g-1 at 5.0 A g-1). Ex situ X-ray photoelectron spectroscopy (XPS) tests reveal that covalent C-S bonds can undergo a reversible reaction with K to form K2Sx. In situ electrochemical impedance spectroscopy (EIS) results suggest that the diffusion of long-chain potassium polysulfides may be the main reason for the degradation of SDHC during long-term cycling. Moreover, using SDHC-700 as the anode and commercial activated carbon as the cathode, a dual-carbon potassium-ion hybrid capacitor has been successfully constructed, which can deliver a high energy/power density of 96.5 Wh kg-1/160.3 W kg-1. This study provides a straightforward and practical approach for developing sulfur-doped hard carbons as high-performance anode materials for alkali metal ion storage.

Super microporous sulfur-doped hard carbon synthesized from a π-stacked Polybenzo[c]thiophene boosting reversible lithium-ion insertion at room temperature

Synthesis of porous carbon materials with controlled textural properties is an all-time challenging process for energy storage applications. Aromatic polymers possess high rigidity due to their π-π stacking arrangement and could serve as robust precursors to produce porous carbon. Herein, super-microporous sulfur-doped hard carbons (SM-SDHCs) were synthesized from a highly ordered aromatic polybenzo[c]thiophene between 600 and 800 °C by using KOH as an activation agent. The degree of carbonization and defects were enhanced as the temperature increased from 600 to 800 °C as confirmed by X-ray diffraction and Raman spectroscopy techniques. All the SM-SDHCs exhibit a super-microporosity (<2 nm) and high surface area (1126–1444 m2 g−1). Among the three synthesized carbons, the SM-SDHC800 exhibited a high discharge capacity of 760.7 mAh g−1 at 20 mA g−1 and showed excellent cycle stability at 200 mA g−1 for 250 cycles. The reversible lithium-ion insertion of SM-SDHC800 anode is accredited to its high degree of carbonization, defect-rich quality, high interlayer distance, and microporous texture with large pore volume (0.68 cm3 g−1). In addition, the excellent cycle stability at 2 A g−1 for 1000 cycles shows its robustness for high C-rate LIBs. Polybenzo[c]thiophene precursor is a perceptive choice to produce sulfur-doped super-microporous hard carbon with controlled textural properties and could bring dramatic advances in the synthesis of nanostructured carbon materials for energy storage applications.

High-performance Zn-ion hybrid supercapacitors enabled by rationally designed hierarchical SiC@C quasi-aligned nanoarrays

In the present work, we report the exploration of rationally designed electrodes based on quasi-aligned nanoarrays composited by the cores of SiC nanowires and shells of sulfur-doped porous carbons (SiC@PC-S), which are directly employed as the free-standing electrodes for Zn-ion hybrid supercapacitors. They behave an ultrahigh areal capacitance of 38.24 mF/cm2 at a scan rate of 10 mV/s, with an exceptional rate capability (~20.67 mF/cm2 even at 1000 mV/s). The as-constructed hybrid supercapacitors deliver a remarkable energy of 10.6 μWh/cm2, which is the highest one among SiC-based supercapacitors ever reported. Moreover, such hybrid devices exhibit a high power density of 7.2 mW/cm2 and a robust cycle stability with ~97 % capacitance retention after 5000 cycles at 2 mA/cm2, representing their promising practical applications.

One-Step Synthesis of Sulfur-Doped Nanoporous Carbons from Lignin with Ultra-High Surface Area, Sulfur Content and CO2 Adsorption Capacity

Lignin is the second-most available biopolymer in nature. In this work, lignin was employed as the carbon precursor for the one-step synthesis of sulfur-doped nanoporous carbons. Sulfur-doped nanoporous carbons have several applications in scientific and technological sectors. In order to synthesize sulfur-doped nanoporous carbons from lignin, sodium thiosulfate was employed as a sulfurizing agent and potassium hydroxide as the activating agent to create porosity. The resultant carbons were characterized by pore textural properties, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The nanoporous carbons possess BET surface areas of 741-3626 m2/g and a total pore volume of 0.5-1.74 cm3/g. The BET surface area of the carbon was one of the highest that was reported for any carbon-based materials. The sulfur contents of the carbons are 1-12.6 at.%, and the key functionalities include S=C, S-C=O, and SOx. The adsorption isotherms of three gases, CO2, CH4, and N2, were measured at 298 K, with pressure up to 1 bar. In all the carbons, the adsorbed amount was highest for CO2, followed by CH4 and N2. The equilibrium uptake capacity for CO2 was as high as ~11 mmol/g at 298 K and 760 torr, which is likely the highest among all the porous carbon-based materials reported so far. Ideally adsorbed solution theory (IAST) was employed to calculate the selectivity for CO2/N2, CO2/CH4, and CH4/N2, and some of the carbons reported a very high selectivity value. The overall results suggest that these carbons can potentially be used for gas separation purposes.

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.

Effect of activator/precursor mass ratio on sulfur-doped porous carbon for catalytic oxidation of aqueous organics with persulfate.

Sulfur-doped porous carbon has emerged as promising metal-free catalysts toward persulfate (PS) for catalytic oxidation of aqueous organics. Wherein, thermal pyrolysis with activator activation is very common for the preparation of activated carbon. However, the relationship between the mass ratio of activator/precursor and catalytic efficiency has been rarely reported. Herein, a series of sulfur-doped porous carbons (S-AC) were synthesized by one-step chemical activation of (Poly(phenylene sulphide) (PPS)) with K2CO3 as activator at K2CO3/PPS mass ratio ranging from 0 to 3. The effects of K2CO3/PPS mass ratio on its physicochemical properties and its catalytic performance for p-chlorophenol (PCP) degradation with PS were comprehensively investigated. Experiment results show that sulfur doping enhanced its catalytic activity and the sample synthesized with K2CO3/PPS mass ratio of 2 (S-AC-2) exhibited the best adsorption and catalytic performance toward PS for PCP removal. More importantly, S-AC-2 with PS could efficiently degrade various aqueous toxic organics other than PCP, and S-AC-2 showed superior catalytic activity to many recently reported advanced materials. In addition, the effects of several operate parameters, including reaction temperature, PS concentration, pH, humic acid, and inorganic ions on PCP oxidation were evaluated. By combining with the results of quenching experiments and EPR, the PS activation mechanism over S-AC-2 was revealed. Moreover, the reusability and regenerability of S-AC-2 was also studied. It indicates that S-AC-2 showed inferior reusability, but the catalytic activity of which could be fully recovered through thermal treatment at 600°C for 2h in N2.

Effect of activation time on sulfur-doped porous carbon for efficient degradation of organic pollutants with persulfate

Metal-free catalysis by using carbonaceous materials has propelled to the forefront in investigation of persulfate (PS) activation for green degradation of aqueous organic pollutants. Herein, sulfur-doped porous carbons (S-AC) were feasibly produced by chemical activation of Poly (phenylene sulphide) with KOH as activator. The influences of activation time on the porous structure, sulfur doping level, and chemical functionality of the as-prepared carbons were investigated by various characterization means. The S-AC samples were employed as metal-free catalysts to activate PS for phenol removal. Experiments results demonstrated that sulfur doping enhanced the catalytic activity of S-AC, and the S-AC-2 sample prepared by carbonization activation of 2 h was demonstrated to be a promising alternative to common metal oxides and other advanced carbon-based materials. Moreover, the S-AC-2/PS system could efficiently degrade various organics, which can be a green material for wastewater treatment and environmental remediation. In addition, the effects of various reaction parameters on phenol removal were discussed. It was found that S-AC-2 still presented an outstanding performance in a wide pH range. Furthermore, the PS activation mechanism over S-AC-2 was investigated by a series of classical radical quenching tests, EPR and Linear Sweep Voltammetry.

Facile synthesis of lignosulfonate-derived sulfur-doped carbon materials for photocatalytic degradation of tetracycline under visible-light irradiation

As the only use of 95% of industrial lignin is as a low-value fuel, it is urgent to explore novel approaches to transform lignin into useful materials. Herein, we report the first transformation of lignin into value-added and inexpensive sulfur-doped carbon photocatalysts by one-step carbonization of sodium lignosulfonates in the presence/absence of Na 2 S·9H 2 O. The sulfur-doped carbon photocatalysts were thoroughly characterized by various physicochemical techniques, including N 2 adsorption, X-ray photoelectron spectroscopy (XPS), scanning transmission microscopy (SEM), photocurrent response, photoluminescence (PL) spectroscopy, and electrochemical impedance spectroscopy (EIS). The IR and XPS spectra show that the dominant sulfur species in the prepared carbon materials are thiophene and SO x groups, such as sulfone groups and sulfonic acid groups. Photocatalytic degradation of tetracycline was employed as a model reaction to evaluate the photocatalytic activities of the sulfur-doped carbons. The incorporation of sulfur-containing groups was found to efficiently decrease the band gaps of these carbon materials and enhance photogenerated charge carrier separation and transfer, thus boosting the tetracycline degradation efficiency. The active sulfur species potentially responsible for the photocatalytic degradation of tetracycline and the degradation mechanism of tetracycline were determined. An innovative strategy for the valorization of lignin to produce valuable carbon photocatalysts was developed in this study. • Sulfur-doped carbon photocatalysts have been prepared from lignosulfonate for the first time. • The introduction of sulfur-containing groups can efficiently boost photocatalytic degradation of tetracycline. • Sulfur-containing groups reduce the band gap and suppress charge carrier recombination. • This work offers a new strategy for the high-value utilization of lignin to carbon photocatalysts.

New insights into N, S doped carbon from conjugated polymers for efficient persulfate activation: Role of hydrogel beads in enhancement of stability

One-pot design of heteroatoms doped carbocatalysts for remediation of wastewater via persulfate (PS) activation is strongly desirable. Herein, a novel nitrogen and sulfur doped and co-doped carbons with controllable N, S doping is rationally prepared using pyrolysis strategy from polypyrrole-polythiophene polymers and copolymer. The N, S co-doped carbon (NS-C) show highly catalytic oxidation compared by N doped carbon (N-C) and S doped carbon (S-C) due to the synergistic effect between N and S dopants. It’s supposed that N and S doping can effectively create highly and main active sites to the electron transfer via PS activation, which could generate reactive oxygen species (ROS). Structure-dependent activity during activation of PS was confirmed by quenching experiments and electron paramagnetic resonance (EPR) analysis, prove that the non-radical species (1O2) is the main ROS generated. To improve the carbocatalyst separation and stability, the hydrogel beads-based alginate NS-C@Alginate were easily prepared. The catalytic efficiency rate by using the real water matrix shows that the NS-C/PS synergic system non-radical-led pathway exhibited a high ability to remediation of surrounding inorganic or organic compounds. This approach provides an innovative method for production and proves an efficient and environmentally benign carbocatalyst to PS activation for practical applications.

Sulfur-Doped Carbons from Durian Peels, Their Surface Characteristics, and Electrochemical Behaviors.

Durian peels are an agricultural waste in Asian countries, including Thailand, Indonesia, and Malaysia, which can be used as a precursor for the production of activated carbon. The objective of this work is to produce activated carbon from durian peels by chemical activation using sodium sulfite (Na2SO3) as an activating and sulfur-doping agent. The process parameter investigated in this study was the activation temperature (500–900 °C) at a fixed impregnation ratio (durian to activating agent of 1:1, by weight). Specific surface areas and pore structures were determined by nitrogen adsorption and desorption measurements, and elemental compositions were characterized by CHNSO analysis. The chemical structure and surface functionality were examined by X-ray photoelectron spectroscopy. The electrochemical behavior of the obtained activated carbon was characterized in 6 M KOH using a three-electrode configuration. It was found that the sulfur content decreases with activation temperature. In contrast, the specific surface area of the activated carbon increases with activation temperature. However, the sample activated at 900 °C with the highest specific surface area (1499 m2 g–1) has a lower specific capacitance (166 F g–1) than the one activated at 700 °C (183 F g–1). This could be due to the presence of a pseudocapacitance caused by the organic sulfur functional groups such as thiophene, sulfone, and sulfoxide, which can trigger a surface redox reaction, leading to a higher capacitance.

Magnetic sulfur-doped carbons for mercury adsorption

Mercury pollution is a significant threat to the environment and health worldwide. Therefore, effective and low-cost absorbents that are easily scalable are needed for real-world applications. Enlarging the surface area of the materials and doping with heteroatoms are two of the most common strategies to cope with this problem. Sulfur-doped activated carbon synthesized from the carbonization of inverse vulcanized thiopolymers makes it possible to combine both large specific surface area and doping of heteroatoms, resulting in outperformance in mercury uptake against commercial activated carbons. Convenient recovery of mercury absorbents after treatment should be beneficial in mercury collecting and recycling. Therefore, magnetic sulfur-doped carbons (MSCs) were prepared by functionalizing sulfur doped carbons through chemical precipitation with magnetic iron oxides. Besides the characterisations of materials, mercury uptake experiments, such as stactic test, capacity test, impact of solution pH, and mixed ions interferences were performed. These MSCs exhibit high specific surface area (1,329 m2/g), high sulfur content (up to 14.8 wt%), porous structure, low cost, and are convenient for retrieval. MSCs are demonstrated high uptake capacity (187 mg g-1) and efficiency in mercury solution and multifunctional absorption in mixed ions solution, showing their potential to be applied in water purification and environmental remediation.

Sulfur-doped 3D hierarchical porous carbon network toward excellent potassium-ion storage performance

Carbonaceous materials are promising anode candidates for potassium-ion batteries, but currently the unsatisfactory cycling and rate performances due to the sluggish diffusion kinetic and serious structure damage during K+ insertion/extraction limit their practical application. Herein, a series of sulfur-doped porous carbons (SPCs) were prepared via a template-assisted freeze-drying followed by the carbonization and sulfuration processes at different temperatures. Among the three as-synthesized samples, SPC-600 exhibits the highest specific capacity (407 mAh·g−1 at 0.10 A·g−1), the best rate (242 mAh·g−1 at 2.00 A·g−1) and cycling performance (286 mAh·g−1 after 800 cycles at 0.50 A·g−1). All the SPCs display higher capacities than the undoped carbon materials. The excellent electrochemical performance of SPC can be ascribed to the abundant three-dimensional porous structure together with S-doping in the disordered carbon, which is favor of providing adequate reaction active sites as well as fast ion/electron transport paths. The density functional theory (DFT) calculations further demonstrate that the sulfur-doping can promote K-ion adsorption and storage. Meanwhile, the kinetic analyses reveal that surface-induced capacitive mechanism dominates the K-ion storage process in SPCs, which contributes to ultrafast charge storage. This work provides an effective strategy for fabricating high-performance potassium-ion storage electrode materials.

Single Alkali Metal Ion-Activated Porous Carbon With Heteroatom Doping for Supercapacitor Electrode.

A single alkali metal ion activation method was used to prepare sulfur-doped microporous carbons. A series of alkali metal ions such as Li+, Na+, K+, and Cs+ was used in the polymerization process of 3-hydroxythiophenol and formaldehyde to obtain metal ion anchored in the sulfur-containing resin, which was further treated to obtain xerogel and carbonized to obtain microporous carbon with sulfur doping. In this case, the monodispersed alkali metal ions could realize highly effective activation with low activating agent dosage. Intensive material characterizations show that the alkali metal ions determine the pore structure and surface properties of as-prepared carbons. C-Cs prepared by Cs+ ion possesses a high Brunauer–Emmett–Teller specific surface area of 1,037 m2 g−1 with interconnected microporosity and sulfur doping. The specific capacitance of C-Cs can reach up to 270.9 F g−1 in a two-cell electrode measurement system, whereas C-Cs-based supercapacitors can deliver an energy density of 7.6 Wh kg−1, which is much larger than that of other samples due to its surface functionalities and well-interconnected porosities.

Ultrafine Cu6Sn5 nanoalloys supported on nitrogen and sulfur-doped carbons as robust electrode materials for oxygen reduction and Li-ion battery

Ultrafine Cu6Sn5 nanoalloys supported on porous N and S-doped carbons (Cu6Sn5@N–S–Cs) were prepared by annealing Cu–Sn-contained covalent organic frameworks (COFs). The Cu6Sn5 alloys with particle size of about 2–10 nm were formed on the surface of N–S–Cs in a high dispersion state. The Cu6Sn5@N–S–Cs were found to efficiently catalyze oxygen reduction reaction (ORR) in both alkaline and acidic media, with half-wave ORR potential (E1/2) of 0.86 V in 0.1 M KOH and 0.67 V in 0.1 M HClO4. The ORR performance of Cu6Sn5@N–S–C could be competitive to the best Fe (or Co)-based non-precious metal electrocatalysts and commercial Pt/C. Cu6Sn5@N–S–C also showed better durability for ORR in both media. Moreover, Cu6Sn5@N–S–C also possessed electrochemical lithium ion storage capacity of 905 mA h g−1 in an initial discharge at the current density of 50 mA g−1, with the outstanding coulomic efficiency. The synergistic effects of ultrafine Cu6Sn5 nanoalloys and porous N–S–Cs contributed to the impressive ORR performance and lithium storage capacities. COFs-derived Cu6Sn5@S–N–C was demonstrated to be a promising bifunctional electrode material for proton exchange membrane fuel cells and lithium ion batteries.

Salt Template Synthesis of Nitrogen and Sulfur Co-Doped Porous Carbons as CO2 Adsorbents

Because of their high stability, low cost, and tunable porosity, porous carbons are of great interest as CO2 adsorbents. The influences of porosity and heteroatom doping on CO2 adsorption depend on the specific adsorption conditions. In the current work, nitrogen and sulfur co-doped carbons were prepared with the assistance of an NaCl template, and the effects of different physicochemical parameters on CO2 adsorption at 20 bar were investigated. The co-doped carbons were synthesized with sodium lignosulfonate as the starting material and urea as the nitrogen source. The material showed a high specific surface area and pore volume of 973 m2/g and 0.50 cm3/g, respectively. Sulfur-doped carbons were also prepared without the addition of urea. Sulfur doping demonstrated positive effects on CO2 adsorption at a low pressure. The sulfur-doped carbons showed adsorption properties similar to those of the co-doped carbons. The CO2 uptake at 298 K and 20 bar was in the range of 4.3–7.5 mmol/g. The experiment results...

Reversing the charge transfer between platinum and sulfur-doped carbon support for electrocatalytic hydrogen evolution

Metal–support interaction is of great significance for catalysis as it can induce charge transfer between metal and support, tame electronic structure of supported metals, impact adsorption energy of reaction intermediates, and eventually change the catalytic performance. Here, we report the metal size-dependent charge transfer reversal, that is, electrons transfer from platinum single atoms to sulfur-doped carbons and the carbon supports conversely donate electrons to Pt when their size is expanded to ~1.5 nm cluster. The electron-enriched Pt nanoclusters are far more active than electron-deficient Pt single atoms for catalyzing hydrogen evolution reaction, exhibiting only 11 mV overpotential at 10 mA cm−2 and a high mass activity of 26.1 A mg−1 at 20 mV, which is 38 times greater than that of commercial Pt/C. Our work manifests that the manipulation of metal size-dependent charge transfer between metal and support opens new avenues for developing high-active catalysts.

Supercapacitance and oxygen reduction characteristics of sulfur self-doped micro/mesoporous bio-carbon derived from lignin

The growing global concerns about the increased fossil fuel consumption and related environmental issues have motived scientists to find new, green and sustainable energy resources and technologies. In this work, byproduct lignin biomass was successfully converted into sulfur self-doped carbon via in-situ hydrothermal carbonization followed by thermal annealing. The sulfur surface content in the as-prepared porous carbon is up to 3.2 wt % as indicated by the XPS measurements. Beyond the traditional synthesis methods which employ KOH or ZnCl2 treatment to activate the carbon surface, the developed synthesis strategy doesn't include such separate activation step. Activation of the as-prepared porous carbons has been conducted in-situ via a calcium ions during the synthesis process. The resulting materials displayed high BET surface areas up to 660 m2 g−1 along with micro/meso porosity and graphitic/amorphous carbon structure. The as-prepared sulfur self-doped electrode materials displayed high electrochemical activity for supercapacitor applications. The sulfur-doped carbon SC-850 electrode exhibited capacitance of 225 F/g at a current density of 0.5 A/g, and high durability where the electrode capacitance did not change over 10,000 cycles at harsh conditions. Additionally, the as-prepared sulfur-doped carbons are promising catalysts for oxygen reduction reaction with 3.4 electrons transferred per molecule at 0.8 V, which approaches the optimum 4-electron pathway.

Effect of Porosity Parameters and Surface Chemistry on Carbon Dioxide Adsorption in Sulfur-Doped Porous Carbons.

In this work, a series of highly porous sulfur-doped carbons are prepared through physical activation methods by using polythiophene as a precursor. The morphology, structure, and physicochemical properties are revealed by a variety of characterization methods, such as scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and nitrogen sorption measurement. Their porosity parameters and chemical compositions can be well-tuned by changing the activating agents (steam and carbon dioxide) and reaction temperature. These sulfur-doped porous carbons possess specific surface area of 670-2210 m2 g-1, total pore volume of 0.31-1.26 cm3 g-1, and sulfur content of 0.6-4.9 atom %. The effect of porosity parameters and surface chemistry on carbon dioxide adsorption in sulfur-doped porous carbons is studied in detail. After a careful analysis of carbon dioxide uptake at different temperatures (273 and 293 K), pore volumes from small pore size (less than 1 nm) play an important role in carbon dioxide adsorption at 273 K, whereas surface chemistry is the key factor at a higher adsorption temperature or lower relative pressure. Furthermore, sulfur-doped porous carbons also possess good gas adsorption selectivity and excellent recyclability for regeneration.