Carbon Letters最新文献

This article describes an efficient electrochemical sensor based on a graphene oxide- manganese dioxide (GO-MnO₂) nanocomposite for detecting acetaminophen (AAP) in human fluids. The MnO₂-wrapped GO sensing element was prepared by a simple and environmentally friendly co-precipitation method. The prepared GO-MnO₂ nanostructure was characterized for its structural, morphological, and functional properties and tested for AAP detection. At a pH of 3, the electrochemical results revealed a high redox process toward AAP due to the transfer of two electrons and protons between the GO-MnO₂/glassy carbon electrode (GO-MnO₂/GCE) and AAP. The differential pulse voltammetry (DPV) analytical results showed the precise sensing ability of AAP in a wide linear range [0.125–2000 µM] with superior anti-interference ability. The calculated sensitivity of the GO-MnO₂/GCE was 17.04 µAµM⁻¹ cm⁻², and the detection limit (LOD) was 7.042 nM. The sensor exhibited high reliability, good reproducibility, and a good recovery range of 98.47–99.22% in human urine sample analysis.

Porous carbon has been intensively used for microwave absorption in merits of its outstanding specific surface area and dielectric properties. This study investigates the microwave absorption capacity of saturated wood-based activated carbon (SWAC) which was used for methylene blue treatment. The results demonstrate that SWAC, subjected to high temperature calcination, exhibits excellent microwave absorption properties. The structure, composition, micro-morphology, and electromagnetic parameters of SWAC were comprehensively analyzed using various techniques. The findings reveal that after calcination, SWAC possesses a rich pore structure, optimized material impedance matching, and the introduction of N atoms from the organic substance methylene blue into the carbon lattice of SWAC, thereby providing dipole polarization loss. These properties significantly contribute to its microwave absorption performance. The optimal reflection loss of SWAC at 6 GHz reaches −50.29 dB with an effective absorption bandwidth of 2.01 GHz, achieved at a calcination temperature of 700 °C and a paraffin matrix additive amount of 25%. The one-step treatment of SWAC proves to be a competitive and cost-effective method for producing microwave absorbers, which holds significant importance for the recovery of SWAC.

Herein, the electrochemical technique was employed to detect hydroquinone (HQ) using a modified glassy carbon electrode (GCE) with reduced graphene oxide (rGO) and silver (Ag)-decorated tin oxy-nanoparticles (SnONPs) to form Ag@SnONPs/rGO nanocomposites (NC). The Ag@SnONPs/rGO nanocomposites were morphologically characterized using multiple analytical methods such as XRD, Raman, XPS, HR-SEM, and HR-TEM. This study revealed that Ag@SnONPs/rGO-NC exhibits excellent conductivity due to the presence of rGO that provides potential π–π interactions with SnONPs, while Ag enhances electron-transfer kinetics. This facilitates efficient charge transport within the sensor, thereby improving HQ adsorption. The key advantages of the sensor demonstrate a concentration of 0.5–200 µM, and a low detection limit value of 0.010 µM, and a high sensitivity value of 6.0746 µA µM⁻¹ cm². Under optimal conditions, the Ag@SnONPs/rGO sensor may be used to determine HQ and its concentration using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The Ag@SnONPs-rGO/GCE sensor demonstrated excellent reproducibility, repeatability, and stability. Moreover, the suggested bimetallic nanocomposite effectively determined the presence of HQ in water and cosmetic samples.

The mass production of highly crystalline carbon nanotubes (CNTs) is highly demanded, yet achieving it remains challenging due to incomplete understanding of how synthetic parameters, except temperature, affect the crystallinity of CNTs. Notably, the choice of carbon precursor significantly influences CNT synthesis, but its impact on crystallinity remains unclear. Here, we employed a data analytics approach to examine the effect of carbon precursors on CNT crystallinity during their synthesis in a fluidized bed reactor. We compared ethylene, acetylene, and a mixture of these. Using Bayesian optimization (BO), we optimized synthesis conditions to maximize I_G/I_D of CNTs for each precursor. Key parameters considered were reaction temperature, precursor concentration, and hydrogen concentration. We conducted three separate BO processes to evaluate the effectiveness of each carbon precursor on CNT crystallinity. The results indicated no significant difference in I_G/I_D of CNTs among the carbon precursors. In addition, multiple linear regression analysis did not support a synergetic effect between acetylene and ethylene. Interestingly, contour plots demonstrated consistent relationships between synthesis parameters and I_G/I_D across different carbon precursors. This data analytics approach allowed us to successfully assess the impact of carbon precursors on the CNT crystallinity and analyze the relationship between synthesis parameters and CNT crystallinity.

Supercapacitors, emerging as energy storage devices, face challenges in practical applications due to their relatively low energy density. In this study, we fabricate a novelty supercapacitor cathode composed of Co₉S₈, conductive phosphorus-doped carbon (P–C), and layered double hydroxides (LDH). The incorporation of a conductive layer significantly enhances charge transfer, capacity, and electrochemical stability, ultimately elevating the electrochemical performance of the cathode. The fabricated Co₉S₈@P–C@NiCo-LDH demonstrates an exceptional area-specific capacitance of 3.9 F cm⁻² at a current density of 2 mA cm⁻², along with remarkable cyclic stability, maintaining 98.9% of their capacity after 2000 cycles. The flexible asymmetric all-solid-state supercapacitor (AAS) assembled with Co₉S₈@P–C@NiCo-LDH and activated carbon (AC) exhibits a remarkable energy density of 0.065 mWh cm⁻², corresponding to 325.0 W h kg⁻¹. Moreover, it maintains excellent cycling stability even at elevated current densities of 10 mA cm⁻². Following 5000 consecutive charge/discharge cycles, the AAS device maintains approximately 91.1% of its initial specific capacity. The AAS device successfully powered a 3V white LED for 5 min, further emphasizing its practicality.

Food contamination with heavy-metal ions and nitrites poses a serious threat to human health. Consequently, the development of fast and sensitive platforms for detecting these contaminants is urgently needed. In this study, a novel sensing platform was developed by integrating carbon nanotubes generated by the pyrolysis of waste masks (WMCNTs) with ZIF-8 for the simultaneous detection of Cd²⁺, Pb²⁺, and nitrite. Specifically, the electronic structure of the WMCNT backbone was modulated by doping with B and N atoms. Nanoporous ZIF-8 was then grown in-situ on its surface to produce composites with enhanced electrical conductivities and large specific surface areas. This modification provided more active sites for the attachment of heavy-metal ions and nitrites. Under optimized conditions, the sensing platform exhibited a wide linear range with the Pb²⁺, Cd²⁺, and NO₂⁻ limits of detection of 2.68, 12.12, and 5.94 μM, respectively. Notably, the sensing platform demonstrated excellent anti-interference capabilities and effectively detected nitrites and heavy-metal ions in pickled foods.

Graphical abstract

Environmental-friendly photocatalytic technology is attracting considerable attentions in the filed of antibiotic degradation. In this work, an innovative Ag/ZnO/Bi₂WO₆ catalyst was fabricated using sol–gel and ultrasonic methods for the degradation cefuroxime sodium in wastewater. The optimized Ag/ZnO/Bi₂WO₆ photocatalyst demonstrated the a remarkable 77.0% photocatalytic efficiency within 180 min under simulated solar sunlight, with an apparent rate constant of 0.01085 min⁻¹. This efficiency is notably 6.02 and 1.41 times higher than that of pure ZnO and Ag/ZnO, respectively. The Ag/ZnO/Bi₂WO₆ photocatalyst achieved a degradation efficiency of up to 72.3% in tap water and polluted river water, while achieving 65.7% degradation in pulping wastewater and pharmaceutical wastewater. Experiments involving reactive species scavenging and electron paramagnetic resonance implied that hydroxide radicals were the predominant active species responsible for the degradation. The enhanced catalytic mechanism and degradation pathway were elucidated, providing valuable insights into the construction and development of high-performance catalysts based on zinc oxide.