Carbon Letters最新文献

This research highlights the use of a WO₃:CeO₂@MXene/gC₃N₄ (MGWC) nanodisk as a versatile material. MGWC demonstrates efficient photocatalytic degradation of moxifloxacin (MOF) in water under sunlight and also shows great promise for high-performance supercapacitor applications. MGWC was synthesized using a modified hydrothermal method and thoroughly characterized using various techniques. The MGWC showed a band gap energy of 2.79 eV determined through UV–Vis DRS analysis and an average crystallite size of 39.6 nm calculated from XRD. A promising photocatalytic activity was observed for the degradation of MOF, outperforming other photocatalysts. Additionally, preliminary studies examined variations in catalyst concentration, pH, kinetics, electrolytes, scavengers, reusability, and TOC, contributing valuable insights. Under optimal conditions, the MOF achieved almost complete degradation, reaching about 99.7% within 180 min using the MGWC photocatalyst. Additionally, MGWC exhibits promising potential in supercapacitor applications. EIS and CV studies have been used to examine MGWC’s exceptional charge transfer properties. CV tests confirm the pseudo-capacitive nature of MGWC electrodes. GCD studies of MGWC exhibit a high specific capacitance of 551 F/g at 1 A/g with incomparable capacitance retention of 98.1% over 10,000 cycles. This research not only aids in reducing emerging environmental pollutants but also sets the stage for sustainable energy solutions.

With the increasing demand for flexible electronic devices, smaller and lighter flexible supercapacitors have gained significant research attention. Among the various materials, self-supporting reduced graphene oxide (rGO) paper has emerged as one of the most promising electrode materials for supercapacitors due to its low cost, high chemical/thermal stability, and excellent electrical conductivity. Nevertheless, a major drawback of rGO paper is the limited ion diffusion between stacked rGO layers, hindering the effective formation of electrochemical double-layer at the electrode/electrolyte interface. In this study, we prepared the rGO paper derived from ball-milled followed-by water oxidation process for reducing the sheet size. The smaller-sized rGO sheets facilitated ion transport between graphene layers, promoting efficient electric double-layer formation. Moreover, the increased presence of edge planes in ball-milled rGO sheets achieved high capacitance, further enhancing the performance of rGO as an electrode material. Notably, the 2-BMOX rGO paper obtained from ball-milling and wet-oxidized graphite exhibited a capacitance of 117.9 F/g in cyclic voltammetry (CV) and 128.6 F/g in galvanostatic charge–discharge (GCD) tests, approximately twice that of conventional rGO. Additionally, the capacitance retained 91% of its initial performance after 2,000 cycles, indicating excellent cycling stability.

Improving the oxygen evolution reaction (OER) performance or replacing OER with the value-added conversion of biomass is of great significance for the green hydrogen energy production. In this work, bimetallic species-decorated laser-induced graphene (LIG) was fabricated and demonstrated as the self-supported electrodes towards efficient OER and 5-hydroxymethylfurfural oxidation reaction (HMFOR). Three-dimensional LIG was obtained via one-step irradiation process under ambient conditions, and active metal species were then introduced through electrodeposition, with Ni-based catalyst as the primary catalytic material and Fe and Co as modified metals. Among, LIG-NiFe electrode achieved an extremely low overpotential of 241.7 mV at a current density of 20 mA/cm² for OER and demonstrated long-term stability. This could be attributed to the promoted formation of Ni³⁺ active centers by Fe modified and the intrinsic porous structure of LIG providing an enhanced surface area. As for LIG-NiCo, due to the low onset potential of Co for HMF, it could achieve 99.6% HMF conversion and yielded value-added 2, 5-furandicarboxylic acid (FDCA) with a selectivity of 87.1%. Coupled with the merit of facile fabrication of LIG framework, this study demonstrates that LIG-based electrodes assume great practical application value in electrocatalytic reactions.

Graphical abstract

In this study, C.I. Pigment Blue 15:3, an organic phthalocyanine based pigment, was used as a precursor to synthesize activated carbon/copper/copper oxide composite through a carbonization and activation process. The resulting composite was investigated to evaluate the potential use as a hybrid capacitor electrode of supercapacitor and pseudo-capacitor. Precursor was pre-treated at 600 °C, followed by activation at 750 °C using alkaline activating agents (KOH and K₂CO₃). Neutral ZnCl₂ activating agent was also used for activation at 700 °C without pre-treatment to compare the electrochemical performance. The KOH activated sample exhibited the presence of Cu, CuO, and Cu₂O in XRD and XPS analysis results and it also showed a highest specific surface area of 2731 m²/g and well-developed 0.7–2.0 nm micropores, enhancing ion adsorption in K₂SO₄ electrolyte. Electrochemical tests revealed that PB_KOH exhibited the highest capacitance, outperforming commercial Norit Carbon at various current densities, due to its Cu/CuO/Cu₂O/activated carbon composite structure. These findings highlight its strong potential as a high-performance supercapacitor electrode material.

Single-walled carbon nanotubes (SWCNTs) are a promising material for advancing the field of materials. However, controlling the controlled growth of SWCNTs by conventional chemical vapor deposition or other growth processes remains challenging. Recent studies have shown that some progress has been made in the synthesis mechanism, catalysts and growth processes of SWCNTs, which makes the controlled growth of SWCNTs possible. This paper reviews the common SWCNTs, the synthesis process, and the applications. The paper firstly discusses the differences in the structure and properties of different types of SWCNTs and the related studies on these properties. Next, the paper discusses the mechanisms, catalysts, and growth processes used to synthesize SWCNTs, from experimental characterization to simulation analysis. Subsequently, the paper describes some applications of SWCNTs in popular fields such as functionalization, transistors, electrochemistry, and so on. Finally, a brief outlook on the challenges and future development of these SWCNTs in the research field is presented.

Modifying the softening point (SP) of pitch is crucial owing to its substantial influence on pitch applicability. This study presents a novel fluorination technique for engineering the SP of mesophase pitch (MP). Low-concentration fluorine gas was used to modify the edge sites of the MP, allowing for either an increase or decrease in the SP by controlling the gas reactivity. The fluorination was conducted with 20 vol% F₂ gas under reaction temperature of 25, 50, and 75 ℃ for 2 h in atmospheric pressure. A reduction in SP was achieved through edge alkylation, with a decrease of up to 14.1% observed after the fluorination. Conversely, an increase in SP resulted from edge dealkylation at higher reaction temperatures. As the modified MPs retained perfect anisotropy, this study offers an effective strategy for adjusting the SP to meet application needs without causing structural deterioration.

Double-layer supercapacitors (SC_s) based on carbon quantum dots (CQDs) are a novel and highly potential electrical energy storage technology. They have a high-power density (P_d) and a long span life, which are desirable for electric automobiles, however, their specific capacitance (C_sp) needs to be improved. Here, we introduce an affordable and environmentally sustainable method to enhance the capacitance of Boron-Sulphur doped carbon quantum dots (B,S-CQDs) from Oloptum miliaceum (Grass) via the hydrothermal method. The findings show that heteroatom-doping might greatly enhance the C_sp and energy density (E_d) when compared to undoped CQDs. As a consequence, the B,S-CQDs demonstrate a high C_sp of 390 F g⁻¹ at 0.1 A g⁻¹ and 152 F g⁻¹ at 1.0 A g⁻¹, revealing excellent rate performance. Along with the electrode demonstrates superb coulombic efficiency with only 2% efficiency loss after 3000 cycles. Furthermore, the B,S-CQDs with a wide voltage range of 0.8 V yields a remarkable E_d of 48.0 Wh kg⁻¹ and P_d of 524 W kg⁻¹. These promising findings demonstrate an economical and environmentally friendly electrode material for high-performance SC_s. This study offers ideas for the design and preparation of SC_s electrode materials and represents a major endeavour to turn waste biomass (smilograss) into a useful electrode material.

Based on a carbon emission inventory of China’s cement industry, this study evaluates the performance of six machine learning models—ridge regression (RR), polynomial regression (PR), random forest (RF), support vector machine (SVR), gradient boosted regression tree (GBRT), and feed-forward neural network (FNN)—in predicting carbon emissions. Model accuracy, feature importance, and residual distributions were analyzed. Results show that clinker production and coal consumption are the dominant factors, contributing 83.7% and 11.95% to emissions, respectively. PR and FNN achieved the best performance with R² values up to 0.99 and lowest mean square errors (0.11 and 1.82). Their mechanisms were further adapted to improve the generalization of other models. Spatial analysis revealed that North, South, and Southwest China are major emission regions. Using the optimal model, emissions in 2035 are projected to reach 519.14 million tonnes. This study offers technical insights for model optimization and supports low-carbon policymaking in the cement industry.

In this study, we investigated the effect of excess sodium (Na) in a NaMnO₂ structure using one-step heat treatment at 900 °C followed by quenching in liquid nitrogen (N₂). According to the X-ray diffraction (XRD) analysis, there was a competition between the monoclinic and orthorhombic phases, and we found that there were two monoclinic phases with similar structural properties. Therefore, we focused on revealing the formation of two isostructures of the monoclinic phase triggered by Na ions. We found that the lattice parameters and β angle changed from 113° to 105° in the samples with increasing Na content. Structural analysis of the powders using the XRD data was conducted using Rietveld refinement, and the phase ratios for all samples were calculated. The sample with x = 1.3 showed a 95% α-phase. To understand the formation of the two isostructures, we performed Density functional theory (DFT) calculations to examine their band structure, stability, and formation energy. A structural analysis of the excess Na-doped samples was performed using common techniques, and it was found that excess Na caused the formation of a coating on the grains in the form of sodium oxide. To validate this prediction, we conducted inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy coupled with energy dispersive X-ray (SEM–EDX) analyses using the basic properties of these techniques and their interactions with materials. In the second part of the study, we produced HC from locally sourced olive leaves and investigated their structural properties. The electrochemical properties of the electrode materials were examined using a half-cell configuration as electrodes with Na metal and a full-cell configuration using x = 1.3 cathode and HC anode. A direct-contact pre-sodiation strategy was used as the anode in the full-cell measurements. It was found that the full cells had initial capacity values of 150 mAh/g for the voltage range 1.5–4.3 V and 120 mAh/g for the voltage range 1.5–3.5 V.

To explore the heating characteristics of activated carbon in a microwave field, the effects of microwave irradiation power, the radius and physical properties of activated carbon, and a symmetrical waveguide on the heating characteristics of activated carbon in a microwave field were studied by experiments and simulation. This study distinguishes itself from previous works by focusing on high-power microwave heating (up to 800 W) and providing a comprehensive analysis of key parameters such as radius, thermal conductivity, magnetic conductivity, and dielectric constant. Additionally, the use of symmetrical waveguides and their impact on heating efficiency represents a novel contribution to the field of microwave-assisted flue gas desulfurization. According to the results, with the increase in microwave irradiation power, the heating rate of activated carbon in the microwave field increases, and the final temperature also rises. Waveguides significantly influence the heating characteristics of activated carbon. When multiple waveguides act on the same microwave field, electromagnetic waves interfere with each other and affect the distribution and intensity of the electromagnetic field. With an increase in the imaginary part of the relative permittivity, the real part of the relative magnetic permeability, and the thermal conductivity of the heated material, the heating characteristics of activated carbon in the microwave field are improved. This study provides a theoretical model for the heating characteristics and temperature distribution of activated carbon in a microwave field under high irradiation power.