Search Results (12)

A novel tungsten-based heterojunction nanocomposite material was developed for the efficient oxidative desulfurization (ODS) of fuel oil, enabling the production of low-sulfur fuel and a reduction in harmful SO_x emissions. In this material, the WC/W₂C heterojunction was uniformly immobilized on a porous nitrogen-doped carbon (NC) matrix structure through facile in situ pyrolysis of polyaniline–phosphotungstic acid (PANI/PTA) precursors. The resultant WC/W₂C@NC catalyst demonstrated remarkable desulfurization performance, achieving 100% removal of 4000 ppm dibenzothiophene (DBT) in just 15 min at 60 °C in the presence of 0.03 g of WC/W₂C@NC and a H₂O₂/S molar ratio of 2. This exceptional activity is attributed to the synergistic effects stemming from the accelerated electron transfer by the NC matrix, the intricate porous network, and the abundant WC/W₂C heterojunction active sites. Moreover, the in situ formation of NC around WC/W₂C mitigated active site leaching, ensuring remarkable stability, with a DBT removal rate of 97.2% maintained even after eight recycling cycles. This work provides a versatile and scalable approach for fabricating tungsten-based heterojunction catalysts and highlights the potential of WC/W₂C@NC as a high-performance, durable ODS catalyst, paving the way for further advancements in sustainable desulfurization technologies. Full article

Using agricultural and forestry wastes as raw materials, adsorbent materials were prepared for dye adsorption in wastewater, which can minimize the environmental load and fully realize sustainability by treating waste with waste. Taking lignosulfonate as a raw material, due to its molecular structure having more reactive groups, it is easy to form composite materials via a chemical oxidation reaction with an aniline monomer. After that, using a sodium lignosulfonate/polyaniline composite as the precursor, the activated high-temperature pyrolysis process is used to prepare porous carbon materials with controllable morphology, structure, oxygen, sulfur, and nitrogen content, which opens up a new way for the preparation of functional carbon materials. When the prepared O-N-S co-doped activated carbon materials (SNC) were used as adsorbents, the adsorption study of cationic dye methylene blue was carried out, and the removal rate of SNC could reach up to 99.53% in a methylene blue solution with an initial concentration of 100 mg/L, which was much higher than that of undoped lignocellulosic carbon materials, and the kinetic model conformed to the pseudo-second-order kinetic model. The adsorption equilibrium amount of NC (lignosulfonate-free) and SNC reached 478.30 mg/g and 509.00 mg/g, respectively, at an initial concentration of 500 mg/L, which was consistent with the Langmuir adsorption isothermal model, and the adsorption of methylene blue on the surface of the carbon material was a monomolecular layer. The adsorption of methylene blue dye on the carbon-based adsorbent was confirmed to be a spontaneous and feasible adsorption process by thermodynamic parameters. Finally, the adsorption of SNC on methylene blue, rhodamine B, Congo red, and methyl orange dyes were compared, and it was found that the material adsorbed cationic dyes better. Furthermore, we also studied the adsorption of SNC on different kinds of heavy metal ions and found that its adsorption selectivity is better for Cr³⁺ and Pb²⁺ ions. Full article

Hydrogen from biomass, as a promising alternative fuel, is becoming considerably attractive due to its high energy density and clean emissions. The aqueous phase reforming (APR) of biomass-derived oxygenated hydrocarbons and water is a renewable and efficient pathway for hydrogen production and shows great potential. However, the key to the application of this technique is to develop catalysts with high hydrogen productivity. In this work, we first synthesized polyaniline–platinum (PANI-Pt) organo-metallic hybrid precursors and then obtained a high-loaded (~32 wt.% Pt) and highly dispersed (~3 nm Pt particles) Pt@NC−400 catalyst after pyrolysis at 400 °C, and the nanoparticles were embedded in a nitrogen-doped carbon (NC) support. The Pt@NC−400 catalyst showed an almost three times higher hydrogen production rate (1013.4 μmol_H2/g_cat./s) than the commercial 20% Pt/C catalyst (357.3 μmol_H2/g_cat./s) for catalyzing methanol–water reforming at 210 °C. The hydrogen production rate of 1,2-propanediol APR even reached 1766.5 μmol_H2/g_cat./s over the Pt@NC−400 catalyst at 210 °C. In addition, Pt@NC−400 also exhibited better hydrothermal stability than 20% Pt/C. A series of characterizations, including ICP, XRD, TEM, SEM, XPS, N₂ physisorption, and CO chemisorption, were conducted to explore the physiochemical properties of these catalysts and found that Pt@NC−400, although with higher loading than 20% Pt/C (~23 wt.% Pt, ~4.5 nm Pt particle), possessed a smaller particle size, a more uniform particle distribution, a better pore structure, and more Pt metal active sites. This study provides a strategy for preparing high-loaded and highly dispersed nanoparticle catalysts with high hydrogen productivity and sheds light on the design of stable and efficient APR catalysts. Full article

Nitrogen-doped carbon materials demonstrate high performance as electrodes in fuel cells and higher oxygen reduction reactivity than traditional Pt-based electrodes. However, the formation process of nitrogen-doped carbon materials has long been a mystery. In this study, the formation mechanism of nitrogen-doped carbon materials from polyaniline (PANI) pyrolysis was studied by the combination of in situ pyrolysis vacuum ultraviolet photoionization time-of-flight mass spectrometry (Py-VUVPI-TOF MS) and substrate-enhanced, laser-induced acoustic desorption source time-of-flight mass spectrometry (SE-LIAD-TOF MS). The initial pyrolysis species, including free radicals and intermediates, were investigated via in situ Py-VUVPI-TOF MS during the temperature-programmed desorption process (within tens of microseconds). The pyrolysis residues were collected and further investigated via SE-LIAD-TOF MS, revealing the product information of the initial pyrolysis products. The results show that the edge doping of carbon materials depends on free radical reactions rather than the direct substitution of carbon atoms by nitrogen atoms. Meanwhile, pyrrole nitrogen and pyridine nitrogen are formed by the free radical cyclization reaction and the amino aromatization reaction at the initial stage of pyrolysis, while the formation of graphitic nitrogen depends on the further polymerization reaction of pyrrole nitrogen and pyridine nitrogen. Full article

In this paper, a Si@EG composite was prepared by liquid phase mixing and the elevated temperature solid phase method, while polyaniline was synthesized by the in situ chemical polymerization of aniline monomer to coat the surface of nano-silicon and exfoliated graphite composites (Si@EG). Pyrolytic polyaniline (p-PANI) coating prevents the agglomeration of silicon nanoparticles, forming a good conductive network that effectively alleviates the volume expansion effect of silicon electrodes. SEM, TEM, XRD, Raman, TGA and BET were used to observe the morphology and analyze the structure of the samples. The electrochemical properties of the materials were tested by the constant current charge discharge and cyclic voltammetry (CV) methods. The results show that Si@EG@p-PANI not only inhibits the agglomeration between silicon nanoparticles and forms a good conductive network but also uses the outermost layer of p-PANI carbon coating to effectively alleviate the volume expansion of silicon nanoparticles during cycling. Si@EG@p-PANI had a high initial specific capacity of 1491 mAh g⁻¹ and still maintains 752 mAh g⁻¹ after 100 cycles at 100 mA g⁻¹, which shows that it possesses excellent electrochemical stability and reversibility. Full article

Graphite as a commercial anode for lithium-ion batteries has significant safety concerns owing to lithium dendrite growth at low operating voltages. Li₄Ti₅O₁₂ is a potential candidate to replace graphite as the next-generation anode of lithium-ion batteries. In this work, fluoride-doped Li₄Ti₅O₁₂ was successfully synthesized with a direct double coating of carbon and nitrogen using a solid-state method followed by the pyrolysis process of polyaniline. X-ray diffraction (XRD) results show that the addition of fluoride is successfully doped to the spinel-type structure of Li₄Ti₅O₁₂ without any impurities being detected. The carbon and nitrogen coating are distributed on the surface of Li₄Ti₅O₁₂ particles, as shown in the Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy (SEM-EDS) image. The Transmission Electron Microscopy (TEM) image shows a thin layer of carbon coating on the Li₄Ti₅O₁₂ surface. The fluoride-doped Li₄Ti₅O₁₂ has the highest specific discharge capacity of 165.38 mAh g⁻¹ at 0.5 C and capacity fading of 93.51% after 150 cycles compared to other samples, indicating improved electrochemical performance. This is attributed to the synergy between the appropriate amount of carbon and nitrogen coating, which induced a high mobility of electrons and larger crystallite size due to the insertion of fluoride to the spinel-type structure of Li₄Ti₅O₁₂, enhancing lithium-ion transfer during the insertion/extraction process. Full article

Designing of porous carbon system for CO₂ uptake has attracted a plenty of interest due to the ever-increasing concerns about climate change and global warming. Herein, a novel N rich porous carbon is prepared by in-situ chemical oxidation polyaniline (PANI) on a surface of multi-walled carbon nanotubes (MWCNTs), and then activated with KOH. The porosity of such carbon materials can be tuned by rational introduction of MWCNTs, adjusting the amount of KOH, and controlling the pyrolysis temperature. The obtained M/P-0.1-600-2 adsorbent possesses a high surface area of 1017 m² g⁻¹ and a high N content of 3.11 at%. Such M/P-0.1-600-2 adsorbent delivers an enhanced CO₂ capture capability of 2.63 mmol g⁻¹ at 298.15 K and five bars, which is 14 times higher than that of pristine MWCNTs (0.18 mmol g⁻¹). In addition, such M/P-0.1-600-2 adsorbent performs with a good stability, with almost no decay in a successive five adsorption-desorption cycles. Full article

Biochar is a kind of carbon-rich material formed by pyrolysis of biomass at high temperature in the absence or limitation of oxygen. It has abundant pore structure and a large surface area, which could be considered the beneficial characteristics for electrodes of microbial electrochemical systems. In this study, reed was used as the raw material of biochar and six biochar-based electrode materials were obtained by three methods, including one-step biochar cathodes (BC 800 and BC 700), biochar/polyethylene composite cathodes (BP 5:5 and BP 6:4), and biochar/polyaniline/hot-melt adhesive composite cathode (BPP 5:1:4 and BPP 4:1:5). The basic physical properties and electrochemical properties of the self-made biochar electrode materials were characterized. Selected biochar-based electrode materials were used as the cathode of sediment microbial electrochemical reactors. The reactor with pure biochar electrode (BC 800) achieves a maximum output power density of 9.15 ± 0.02 mW/m², which increases the output power by nearly 80% compared with carbon felt. When using a biochar/polyaniline/hot-melt adhesive (BPP 5:1:4) composite cathode, the output power was increased by 2.33 times. Under the premise of ensuring the molding of the material, the higher the content of biochar, the better the electrochemical performance of the electrodes. The treatment of reed powder before pyrolysis is an important factor for the molding of biochar. The one-step molding biochar cathode had satisfactory performance in sediment microbial electrochemical systems. By exploring the biochar-based electrode, waste biomass could be reused, which is beneficial for the environment. Full article

The fuel cell, as one of the most promising electrochemical devices, is sustainable, clean, and environmentally benign. The sluggish oxygen reduction reaction (ORR) is an important fuel cell cathodic reaction that decides the efficiency of the overall energy conversion. In order to improve ORR efficiency, many efficient catalysts have been developed, in which the N-doped material is most popular. Polyaniline and polypyrrole as common aromatic polymers containing nitrogen were widely applied in the N-doped material. The shape-controlled N-doped carbon material can be prepared from the pyrolysis of the polyaniline or polypyrrole, which is effective to catalyze the ORR. This review is focused on the recent advance of polyaniline or polypyrrole-based ORR electrocatalysts. Full article

The exploration of multifunctional electrode materials has been a hotspot for the development of high-performance supercapacitors. We have used carbon fiber plates recovered from construction waste to prepare high-quality flexible carbon fiber materials by pyrolysis of epoxy resin. The as-prepared recycled carbon fiber has a diameter of 8 μm and is the perfect substrate material for flexible electrode materials. Furthermore, polyaniline and manganese dioxide are uniformly deposited on the recycled carbon fiber by one-step electrodeposition to form an active film. The recycled carbon fiber/polyaniline/MnO₂ composite shows an excellent specific capacitance of 475.1 F·g⁻¹ and capacitance retention of 86.1% after 5000 GCD cycles at 1 A·g⁻¹ in 1 M Na₂SO₄ electrolyte. The composites optimized for electrodeposition time have more electroactive sites, faster ions and electron transfer, structural stability and higher conductivity, endowing the composites promising application prospect. Full article

Nitrogen doped carbon materials as electrodes of supercapacitors have attracted abundant attention. Herein, we demonstrated a method to synthesize N-doped macroporous carbon materials (NMC) with continuous channels and large size pores carbonized from polyaniline using multiporous silica beads as sacrificial templates to act as electrode materials in supercapacitors. By the nice carbonized process, i.e., pre-carbonization at 400 °C and then pyrolysis at 700/800/900/1000 °C, NMC replicas with high BET specific surface areas exhibit excellent stability and recyclability as well as superb capacitance behavior (~413 F $\cdot$ g⁻¹) in alkaline electrolyte. This research may provide a method to synthesize macroporous materials with continuous channels and hierarchical pores to enhance the infiltration and mass transfer not only used as electrode, but also as catalyst somewhere micro- or mesopores do not work well. Full article

Nitrogen-doped ordered mesoporous carbon was synthesized by using polyaniline as the carbon source and SBA-15 as the template. The microstructure, composition and electrochemical behavior were extensively investigated by the nitrogen sorption isotherm, X-ray photoelectron spectroscopy, cyclic voltammetry and rotating ring-disk electrode. It is found that the pyrolysis temperature yielded a considerable effect on the pore structure, elemental composition and chemical configuration. The pyrolysis temperature from 800 to 1100 °C yielded a volcano-shape relationship with both the specific surface area and the content of the nitrogen-activated carbon. Electrochemical tests showed that the electrocatalytic activity followed a similar volcano-shape relationship, and the carbon catalyst synthesized at 1000 °C yielded the best performance. The post-treatment in NH₃ was found to further increase the specific surface area and to enhance the nitrogen doping, especially the edge-type nitrogen, which favored the oxygen reduction reaction in both acid and alkaline media. The above findings shed light on electrocatalysis and offer more strategies for the controllable synthesis of the doped carbon catalyst. Full article