Carbon Doping Research Articles

Air‐Pyrolysis Precision Synthesis of Functional Porous Carbon Materials

AbstractCarbon materials play a pivo tal role across various advanced applications, yet their synthesis traditionally necessitates inert atmospheres to avert oxidation at high temperatures, thus inflating production costs and resource utilization. Achieving precision synthesis of functional porous carbon materials via air‐pyrolysis remains a formidable challenge. Herein, a streamlined, one‐step lava‐like carbonization approach is introduced enabling the fabrication of porous carbons boasting tailored morphologies (0‐3D), elevated specific surface areas (540.7–1047.6 m2g⁻¹), heteroatom doping, and commendable carbon yields (20‐39.1%) through direct pyrolysis within an air environment. Leveraging recyclable boric acid as a reaction medium, a lava‐like flowing protective barrier above 170 °C is engendered that spontaneously creates an oxygen‐free‐like milieu devoid of high pressure or intricate procedures. This boron‐containing lava serves dually as a template and chemical activator, facilitating pore formation and catalyzing porous carbon production. Notably, the method accommodates a spectrum of carbon sources, encompassing sugars, proteins, graphene oxide, and their metal mixtures. The resultant morphologically customizable carbons exhibit excellent performance in areas as diverse as microwave absorption and electrocatalysis. This work pioneers a novel pathway for large‐scale precision synthesis of high‐quality carbon materials via air‐pyrolysis under mild conditions.

Effective Near-Infrared Light-Driven Photocatalytic Reduction of CO2 by Dual-Site Doped Carbon Nitrides

Effective Near-Infrared Light-Driven Photocatalytic Reduction of CO₂ by Dual-Site Doped Carbon Nitrides

Effective Determination of Diosmin Using Nitrogen Doped Carbon Dots as Probe Based on Internal Filtering Effect.

The establishment of a convenient and efficient testing method is crucial and needed for the monitoring of diosmin. In this study, nitrogen doped carbon dots (N-CDs) with the particle size distribution of 2.5-5.7nm and the average diameter of 4.1nm were successfully synthesized using a simple strategy. N-CDs exhibited excellent and stable fluorescence performance with the quantum yield of 22.33%. Correspondingly, a fluorescence analytical method was developed for diosmin determination using N-CDs as probe. UV-vis absorbance spectroscopy and the evaluation of internal filtering parameters verified that the mechanism causing the quenching of N-CDs was an internal filtering effect (IFE). The concentration of diosmin can be directly evaluated based on the quenched fluorescence intensities. After optimizing experimental conditions, it was found that the fluorescence quenching efficiency ((F0-F)/F0) of N-CDs exhibited a good linear relationship with the concentration of diosmin (CDiosmin) in the range of 3.0-50µg/mL. The limit of detection (LOD) was 0.86µg/mL based on 3σ/slope (n = 13). This method was successfully applied to accurately determine the content of diosmin in diosmin tablets and human plasma samples with good reproducibility. It stands out for its simplicity, speed, and acceptable determination performance.

Phosphorous doped graphitic carbon nitride (P‐g‐C3N4) as an electrochemical platform for the simultaneous detection of xanthine and caffeine

A one step strategy was employed for the preparation of phosphorous doped g‐C3N4 (P‐g‐C3N4) using melamine phosphate. Herein, the precursor upon thermal condensation at 550º C resulted in the formation of P‐g‐C3N4 nanosheets. The as‐synthesised P‐g‐C3N4 nanosheets were characterized by UV‐vis, FT‐IR and Raman spectroscopy. Later, surface morphological analysis were carried out using FESEM and HRTEM. Moreover, the crystalline nature and elemental composition analysis were conducted using XRD and XPS. Following this, P‐g‐C3N4 nanosheets modified glassy carbon (GC) electrode was employed for the simultaneous detection of xanthene and caffeine. The modified electrode was found to be linear in the range of 0.1 to 100 μM (for xanthine) and 0.05 to 100 μM (for caffeine). The limit of detection was found to be 10 nM and 14 nM for xanthine and caffeine respectively. Further, the electrode exhibited a highly selective detection towards each of these analyte when they co‐exists.

Enhanced carbon host with N-reinforced S-sites to catalyze rapid iodine conversion kinetics for Zn-I2 battery

Aqueous zinc-iodine (Zn-I2) battery is a promising energy storage system in the establishment of a low-carbon, clean society, but they are limited by unsatisfied reversible capacity and poor cycle life. Ultimately, this is due to the poor iodine conversion kinetics and the shuttle effect of the intermediate polyiodide. Herein, a N-reinforced S-site carbon host (labeled as NS-YP80F) is designed to resolve these issues. DFT calculation shows that the electrochemical activity of the NS-YP80F with abundant S-site can be further enhanced by introducing N-atom at the original S-site. The synergistic effect of N-reinforced S-site carbon host cannot only enhance the adsorption of polyiodide to avoid the shuttle effect, but also induce the smooth conversion of iodine through enhanced catalytic mechanism. Consequently, the Zn-I2 battery with NS-YP80F@I2 cathode shows high reversible capacity (127 mAh g−1 at 1C) and stable cycling lifespan (15,000 cycles) with a high current density of 50 C. This strategy achieved a breakthrough in the electrochemical activity of the heteroatom doping carbon hosts, and provided a simple and effective solution for optimizing the performance of Zn-I2 battery.

Effects of Ni Loadings on the Structure and Morphology of Carbon Nanotubes Using Nickel Doped Iron Oxide Catalysts

AbstractIron oxide and their different doped iron oxide catalyst have been used for decades and are considered as efficient catalysts in several synthesis schemes including synthesis of carbon nanotubes. The iron oxide of the catalyst is abundant in nature, high catalytic activity at low over potentials, stability in basic media and low cost, making it environmentally and economically attractive. Nickel doped iron oxide catalyst have not been reported in the literature. Doping of nickel over iron oxide catalyst, different percentage 1 %, 5 %, 10 % and 20 % were done by impregnation method. The samples were characterized by X‐Ray powder Diffraction (XRD), Fourier‐Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Energy Dispersive X‐ray (EDX) and Thermo Gravimetric Analysis (TGA). Nickel doped iron oxide was used as catalyst for the synthesis of carbon nanotubes (CNTs) and doping changed the morphology of carbon nanotube (CNTs). FTIR results confirmed the doping and presence of different functional groups. Chemical vapor deposition (CVD) was carried out for the synthesis of multiwall carbon nanotubes (MWCNTs) on nickel doped iron oxide catalyst for different percentage (1 %, 5 %, 10 % and 20 %) separately. CVD assembly was carried in tube furnace and the reaction was checked at two different temperature i.e 700 °C and 750 °C and using methane and compressed natural gas (CNG) as precursors. The catalyst was activated in the furnace at 800 °C for an hour. Methane and argon were used in proportion 2 : 1 inside the furnace. SEM showed formation of CNTs at 750 °C with CNG precursor. Formation of CNTs increased with increasing doping with this CNTs was confirmed by SEM.

Energy‐Saving Hydrogen Production from Methanol Electrocatalysis Catalyzed by Molybdenum Phosphide/Nitrogen‐Doped Carbon Polyhedrons Supported Pt Nanoparticles

Comprehensive SummaryImproving the catalytic efficiency and anti‐poisoning ability of Pt‐based catalysts is very critical in methanol electrolysis technology for high‐purity hydrogen generation. Herein, the nitrogen‐doped carbon polyhedrons‐encapsulated MoP (MoP@NC) supported Pt nanoparticles were demonstrated to be effective for methanol electrolysis resulting from the combined advantages. The nitrogen‐doped carbon polyhedrons not only greatly enhanced the conductivity but also effectively prevented the aggregation of MoP to offer Pt anchoring sites. The electronic structure modification of Pt from their interaction reduced the adsorption energy of CO*, resulting in good CO‐poisoning resistance and accelerated reaction kinetics. Specifically, Pt‐MoP@NC exhibited the highest peak current density of 106.4 mA·cm–2 for methanol oxidation and a lower overpotential of 28 mV at 10 mA·cm–2 for hydrogen evolution. Energy‐saving hydrogen production from methanol electrolysis was demonstrated in the two‐electrode systems assembled by Pt‐MoP@NC which required a low cell voltage of 0.65 V to reach a kinetic current density of 10 mA·cm–2 on the glass carbon system, about 1.02 V less than that of water electrolysis.

Synergistic enhancement of lithium iron phosphate electrochemical performance by organic zinc source doping and crystalline carbon layer capping

In this study, lithium iron phosphate (LFP) is prepared as cathode material by hydrothermal synthesis method and the combined effect of doping and capping is applied to co-modify it. We thoroughly investigate how Zn2+ doping and PA capping layer affect the crystal structure, microscopic morphology, and electrochemical properties of LFP cathode materials. The experimental results show that when co-modified with 5 % Zn2+ doping combined with 7 % PA capping layer, the resulting cathode material exhibits a discharge specific capacity of 165.5 mAh g−1, and the capacity retention rate can still be maintained at a high level of 98.6 % after 200 charge–discharge cycles.

Charge carrier dynamics of chemical vapor deposited carbon-doped titanium dioxide photoanodes.

This study explores the synthesis of carbon-doped titanium dioxide TiO2(C) photoanodes through a single-step, low-pressure chemical vapor deposition (LCPVD) method, investigating the influence of carbon doping and oxygen vacancies on photoelectrochemical performance. The research employs morphological, structural, and photoelectrochemical characterization methods, including intensity-modulated photocurrent spectroscopy (IMPS) and distribution of relaxation times (DRT) analysis. We correlate the simultaneous presence of surface carbon and oxygen defects to improved charge separation and collection for TiO2(C) photoanodes. This work provides a comprehensive and detailed explanation of the photoelectrochemical performance of TiO2 electrodes, showing the potential behind combined IMPS-DRT analysis for photoelectrode characterization.

Electrolytic conversion of CO2 to proportionally tunable syngas using nickel-nitrogen doped carbon materials derived from Chlorella sp.

Chlorella sp., a common type of algae found in global surface waters, is prone to causing "blooms" and can accumulate significant amounts of nutrients such as nitrogen, phosphorus, and carbon. While carbon materials derived from Chlorella sp. are widely used in the field of adsorption, there are relatively few reports focused on electrocatalysis. This study utilized Chlorella sp. as a raw material to synthesize functional carbon materials, and prepared nitrogen-doped (CN), nickel-doped (CNi), and nitrogen-nickel co-doped (CNNi) carbon-based catalysts with both metal and non-metal elements. The results showed that the CN, CNi and CNNi catalysts possessed certain electrocatalytic properties, among which the CNNi material had the best electrocatalytic activity towards CO2 reduction (CO2RR). In 1.0 M KHCO3, the CNNi catalyst exhibited an instantaneous current density of 15.4 mA/cm2 under the potential of -0.82V (vs. RHE). In terms of product selectivity, the Faraday efficiency of CO on the CNNi electrode was up to 90% when the electrode potential was -0.62 V (vs. RHE), while the selectivity of the CN and CNi catalysts for CO was only 59% under the optimal conditions. The co-doping of nitrogen and nickel significantly enhanced the electrocatalytic activity and the selectivity towards CO of Chlorella-based carbon materials.

Vanadium doped ZIF-L derived V-NC peroxidase-like nanozymes for tanwenic acid sensing

Transition metal-relied nitrogen doping carbon nanozyme has attracted great attention owning to their high potential to replace natural enzymes. In this study, we prepared novel vanadium doped ZIF-L derived N-doped carbon nanozyme (V-NC) via facilely pyrolysis strategy. The cross-shaped morphology endows V-NC with unique V-Nx active sites, hierarchical pore character and large specific surface area, leading to its good peroxidase-mimetic activity. The steady-state kinetics trials revealed the low Km values of V-NC for TMB and H2O2, demonstrating its good affinity to TMB and H2O2. Mechanism research revealed that the excellent peroxidase-like activity of V-NC resulted from co-participation of •OH and O2•−, which were confirmed by reactive oxygen species (ROS) scavenging experiments and EPR trials. Under optimized operational conditions, and by virtue of the antioxidant properties of tannic acid (TA), a colorimetric sensing programme in terms of the peroxidase-imitating function of V-NC was developed for sensitive detection of TA in the 0.1–2.5 µM linear range with low detection limit of 19.8 nM and the relative standard deviation (RSD, n = 3) of below 5 %. This contribution renders a novel idea for designing and developing high activity N-doped carbon nanozyme, and provides an accurate and feasible assay for the analysis of TA in real samples.

High Performance CMOS RF Switch Based on Highly Carbon Doped Raised Source/Drain Regions

The demand for high-performance Radio Frequency (RF) CMOS RF SOI (Silicon on Insulator) switches has rapidly increased, driven by the need for advanced wireless technologies (1). In this paper we give new insights on high carbon incorporation, where a Si(1-y)Cy layer with 1% of substitutional carbon (y = Csub) is grown on 40 nm on top on silicon. This layer is used for Raised Source/Drain (RSD) to strain the Si channel, for reducing on-state resistivity (Ron) and which should result in a theoretical 16% gain in current (3), (4). Si(1-y)Cy growth parameters were carefully optimized to increase Csub. Firstly, with the reduction of the temperature. Then, with H2 carrier gas reduction and total pressure increase. These two process modifications have a positive impact on the carbon concentration, thanks to the higher growth rate, without layer relaxation (5).

Platinum/Platinum Sulfide on Sulfur-Doped Carbon Nanosheets with Multiple Interfaces toward High Hydrogen Evolution Activity.

Platinum (Pt)-based materials are among the most competitive electrocatalysts for the hydrogen evolution reaction (HER) due to suitable hydrogen adsorption energy. Due to the rarity of Pt, it is desirable to develop cost-effective Pt-based electrocatalysts with low Pt loading. Herein, Pt/PtS electrocatalysts on S-doped carbon nanofilms (PPS/C) have been successfully fabricated through a precursor reduction route with a complex of Pt and 1-dodecanethiol (1-DDT) as the precursor. The PPS/C achieved at 400 °C (PPS/C-400) exhibits excellent HER performances with an ultralow overpotential of 41.3 mV, a low Tafel slope of 43.1 mV dec-1 at a current density of 10 mA cm-2, and a long-term stability of 10 h, superior to many recently reported Pt-based HER electrocatalysts. More importantly, PPS/C-400 shows a high mass-specific activity of 0.362 A mgPt-1 at 30 mV, which is 1.88 times of that of commercial 20% Pt/C (0.193 A mgPt-1). The introduction of sulfur leads to the formation of PtS, which not only reduces the content of Pt but also realizes the interface regulation of Pt/PtS, as well as the doping of carbon. Both regulations make the resulting catalyst have abundant active centers and rapid electron transfer/transport, which is conducive to balancing the adsorption and resolution of intermediate products, and finally achieving great mass-specific activity and stability. The research work may provide ideas for designing effective Pt-based multi-interface electrocatalysts.

Characterisation Analysis of Sulphur and Phosphorous Doped and Co-doped Graphitic Carbon Nitride (g-C3N4) Materials

Graphitic carbon nitride (g-C3N4) is tailored with doping of different non-metals (Sulphur and Phosphorus). For synthesis through thermal condensation method, the mixtures of urea and dopant with diverse concentrations have been added for preparation of materials. The basic effect of doping and its concentration on the structural morphology and absorption spectra of the samples is investigated in detail. Pure g-C3N4 suffers from high recombination rate of photogenerated electron-hole pairs resulting in low photocatalytic activity. Different techniques like X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transforms infrared (FTIR) spectroscopy, and Photoluminescence spectroscopy (PL) have been used for the characterization. X-ray diffraction studies confirm the formation of the g-C3N4 structure and SEM images reveal crumpled sheets and irregular plate like shapes of the doped graphitic nitride samples. FTIR analysis identify the presence of surface amino (N-H) and water (O-H) groups, cyano terminal group (C≡N), (C≡C), C–N) and (C=N) bonds and breathing mode of the tri-s-triazine units in the samples. PL spectra shows that the sulphur and phosphorus co-doped PSGCN (8 wt.%) sample is better for photocatalytic activity.

In-situ ‘X’ doped ‘GCN’ photocatalyst enables selective aldehyde synthesis via photo-oxidation of benzyl alcohol under ambient conditions

Photo-oxidative selective conversion of benzyl alcohols using graphitic carbon nitride (GCN) is a sustainable strategy for conventional metal-doped heterogeneous catalytic oxidation systems. Non-metal doped graphitic carbon nitride (a subclass of GCN) enhances its properties as an efficient photocatalyst for oxidation. These heteroatom non-metal dopants alter the optical energy gap and chemical and electronic properties of GCN, making it ideal for creating cost-effective, practical utility. So, herein, we designed heteroatoms (X = B, S, C) doped GCN photocatalysts derived from melamine (M) with different heteroatom ingredients and compared their activity in detail. Among these, the photo-oxidation of benzyl alcohol under blue LED by S-doped GCN (S-GCN) photocatalyst exhibits utmost higher photocatalytic activity than other heteroatoms doped GCN photocatalyst due to suitable band gap and slow photoinduced charge carriers recombination. The suitable energy gap with higher chemical stability is accountable for the substantial increase in the photocatalytic efficiency of S-GCN in the solar light responsive integrating reactions of oxidation of benzyl alcohol in aerobic conditions. Attaining an exceptional >99 % selectivity towards benzaldehyde (up to 5 cycles without significant loss of activity) marks a remarkable milestone. This opens up new possibilities for using these simple non-metal-doped photocatalysts in fine chemical synthesis.

Ultrathin carbon doped hexagonal boron nitride films for electromagnetic interference shielding in the terahertz region

We have investigated the electromagnetic interference (EMI) shielding efficiency of carbon-doped hexagonal boron nitride (hBN) films in 0.3–1.8 THz regions using transmission-based terahertz time-domain spectroscopy (THz TDS). The hBN films were synthesized on Copper foils by atmospheric pressure chemical vapor deposition (APCVD) utilizing ammonia borane (AB) powder as a precursor. Carbon doping of BN films was achieved by using the intrinsic carbon dissolved in the Copper substrate. The EMI shielding efficiencies and the optical, dielectric, and electrical properties of the films were determined using THz TDS. The Absorbance is much greater than the Reflectance indicating that absorption is the dominant mechanism of shielding in these films. These carbon-doped hBN films show a high EMI shielding effectiveness, with 99.99 % EM radiation blocked. A maximum value of 30 dB and 55 dB at 1.72 THz were observed for films with 4.5 nm and 6.5 nm thicknesses. This is equivalent to shielding efficiency per unit thickness of 6667 dB/µm and 8460 dB/µm, which is among the highest reported for 2D materials.

Effect of variation in band gap via carbon doping in ZnO NPs on its photocatalytic activity in Pb ion removal from water

Effect of variation in band gap via carbon doping in ZnO NPs on its photocatalytic activity in Pb ion removal from water

Understanding the evolution of molybdenum-nitrogen doped carbon with long-term durability for efficient oxygen reduction reaction

The performance and durability of catalyst for Oxygen Reduction Reaction (ORR) still are challenges for fuel cell applications. Mo-NC catalyst system was established and showed the activity comparable with commercial Pt/C in alkaline conditions. An activation phenomenon during longer operation was confirmed with an obvious positive shift after 30 k cycles in accelerated degradation tests, which is rarely observed in the ORR process. The X-ray absorption fine structure (XAFS) indicated a coordination structure transform in electrochemical conditions cause the activated performance. The Density Function Theory (DFT) calculation reveals the transformation of the coordination structure is thermodynamically feasible and also conducive to lower the energy barriers of the key steps in the ORR performance, explaining the origin of the activate phenomenon. These findings give potential guidance to improve both activity and stability of catalyst.

Self-sulfur doped mesoporous novel carbon electrodes derived from poly-anthraquinone sulfide for high-performance supercapacitors! A comparative study

Carbon materials are suitable electrode candidates in supercapacitors (SCs) because of their availability, well-defined microstructures, and ultrahigh surface areas. Herein, a universal chemical activation method was utilized to obtain activated carbon (C-KOH) from poly-anthraquinone sulfide (PAQS) at 850 °C and reduced activated carbon (C-KOH-H) from C-KOH via a mild hydrogen reduction process at low temperature. The electrochemical performances of the PAQS derived activated carbon electrodes were investigated by assembling electric double-layer capacitors (EDLCs). Electrodes fabricated from C-KOH and C-KOH-H showed 174 and 182.3 F g−1 specific capacitances at 0.5 A g−1 current density, respectively. Whereas their energy densities were 44 and 46 Wh kg−1 at 350 and 423 W kg−1 power densities, respectively. SCs assembled from C-KOH-H showed excellent rate performance, that retained 140 F g−1 even at high current density (20 A g−1), while the one assembled with C-KOH stored 54 F g−1. Furthermore, the C-KOH-H electrode retained 98 % of the initial capacitance at 1 A g−1 over 20,000 continuous cycles. The experimental results revealed that C-KOH-H showed the best electrochemical performance in SCs, which is attributed to the presence of less sulfur and oxygen than C-KOH after the mild reduction. These results prove that PAQS show excellent activation with KOH to produce well-organized porous activated carbons having high specific surface areas, which can be utilized as high-performance electrode materials in SCs.

Hydrothermal synthesis, characterization of Co3Sb4O6F6 and carbon doped Co3Sb4O6F6 and their application towards photocatalytic dye degradation, adsorption, catalytic Knoevenagel condensation and bacterial disinfection

Single crystals of Co3Sb4O6F6 have been grown by employing hydrothermal techniques. Table sugar was utilized to prepare carbon-doped Co3Sb4O6F6. The objective was to employ Co(II)-based metal oxyfluoride comprising a stereochemically active lone pair element (Sb3+) and its carbon-doped analogues for the multifunctional applications. The impact of carbon doping on Co3Sb4O6F6 has been evaluated towards the changes in photocatalytic, catalytic, and adsorbent efficiency. The changes in carbon percentage affect the physical and chemical properties of the host material. A larger percentage of carbon doping turns the photocatalytic ability of the host material into an adsorbent for the removal of dye. The single crystal X-ray diffraction study reveals that Co3Sb4O6F6 crystallizes into cubic symmetry. However, powder X-ray diffraction study reveals the structural transformation in the carbon-doped Co3Sb4O6F6. It also reduces the band gap energy of the host material, and 4 wt% C@Co3Sb4O6F6 turns out to be an efficient photocatalyst. Large-scale carbon doping (15 wt%) appears to be an effective strategy to increase the surface charge and BET surface area, as consequences adsorption property develops in 15 wt% C@Co3Sb4O6F6/H2O2 for the elimination of methylene blue (MB). This favourable chemical adsorption process occurs with large maximum adsorption capacity (qmax = 58.41169 mg g-1), as evident from the Langmuir adsorption isotherm. Scavenger experiment confirms that the photocatalytic activities of the as-synthesised compounds were triggered by the active participation of the hydroxyl radical (.OH). The catalytic efficiencies of both parent and doped compounds are also established for the solvent-free Knoevenagel condensation reaction with 90 % yield at moderate temperature. Bacterial disinfection studies by the ‘Disc diffusion method’ confirm that Co3Sb4O6F6 shows better efficiency than the carbon doped compound against both Gram-positive and Gram-negative bacteria.