Search Results (10)

The development of advanced anode materials with high capacity and structural stability addressing the limitations of conventional graphite anodes in theoretical capacity (372 mA h g⁻¹) and severe volume expansion remains a critical challenge for lithium-ion batteries (LIBs). Herein, we propose a structural engineering strategy through high-temperature calcination to construct 2D layered Bi₂O₂Se integrated with optimized 3D carbon nanotube (CNT) frameworks (Bi₂O₂Se–CNT-x). Comprehensive characterization (XRD, Raman, FESEM, XPS) verifies the high crystallinity of Bi₂O₂Se and the successful establishment of 3D conductive networks through interfacial coupling with CNTs. Electrochemical evaluation demonstrates that the optimized Bi₂O₂Se–CNT-2 composite delivers a remarkable initial discharge capacity of 1544.7 mA h g⁻¹ at 0.1 A g⁻¹, significantly outperforming pristine Bi₂O₂Se (124.3 mA h g⁻¹). Notably, it maintains superior rate capability (405.0 mA h g⁻¹ at 2 A g⁻¹, 35.2% capacity retention) and cycling stability (74.8% capacity retention after 250 cycles), attributed to the synergistic effects between 2D Bi₂O₂Se lamellae and the conductive CNT matrix. The 3D CNT network facilitates rapid electron transport while mitigating volume fluctuations, whereas the layered Bi₂O₂Se enables a hybrid storage mechanism combining intercalation, conversion, and alloying reactions. This work broadens the application horizons of 2D layered materials in energy storage systems. Full article

Harnessing waste heat from environmental or industrial sources presents a promising approach to eco-friendly and sustainable chemical synthesis. In this study, we introduce a thermoelectrocatalytic (TECatal) system capable of utilizing even small amounts of heat for hydrogen peroxide (H₂O₂) production. We developed a nanohybrid structure, combining carbon nanotubes (CNTs) and Bi₂Te₃ nanoflakes (Bi₂Te₃/CNTs), through a one-pot synthesis method. Bi₂Te₃, as a thermoelectric (TE) material, generates charge carriers under a temperature gradient via the Seebeck effect, enabling them to participate in surface redox reactions. However, the rapid recombination of these charge carriers greatly limits the TECatal activity. In the Bi₂Te₃/CNTs nanohybrid system, the introduction of CNTs substantially enhances the efficiency of H₂O₂ production, as the strong bonding between CNTs and Bi₂Te₃, along with the excellent conductivity of CNTs, facilitates charge carrier separation and transport, as confirmed by TE electrochemical tests. This study underscores the significant potential of thermoelectric nanomaterials for converting waste heat into green chemical synthesis. Full article

The oxygen evolution reaction (OER) is a key half-reaction in electrocatalytic water splitting. Large-scale water electrolysis is hampered by commercial noble-metal-based OER electrocatalysts owing to their high cost. To address these issues, we present a facile, one-pot, room-temperature co-precipitation approach to quickly synthesize carbon-nanotube-interconnected amorphous NiFe-layered double hydroxides (NiFe-LDH@CNT) as cost-effective, efficient, and stable OER electrocatalysts. The hybrid catalyst NiFe-LDH@CNT delivered outstanding OER activity with a low onset overpotential of 255 mV and a small Tafel slope of 51.36 mV dec⁻¹, as well as outstanding long-term stability. The high catalytic capability of NiFe-LDH@CNT is associated with the synergistic effects of its room-temperature synthesized amorphous structure, bi-metallic modulation, and conductive CNT skeleton. The room-temperature synthesis can not only offer economic feasibility, but can also allow amorphous NiFe-LDH to be obtained without crystalline boundaries, facilitating long-term stability during the OER process. The bi-metallic nature of NiFe-LDH guarantees a modified electronic structure, providing additional catalytic sites. Simultaneously, the highly conductive CNT network fosters a nanoporous structure, facilitating electron transfer and O₂ release and enriching catalytic sites. This study introduces an innovative approach to purposefully design nanoarchitecture and easily synthesize amorphous transition-metal-based OER catalysts, ensuring their cost effectiveness, production efficiency, and long-term stability. Full article

This study aimed to investigate the performance of composite photocatalytic membranes fabricated by incorporating multiple nanoparticles (TiO₂, carbon nanotubes, BiVO₄) into polyvinylidene fluoride membrane material for real dairy wastewater treatment. The composite photocatalytic membranes exhibited superior antifouling behavior, lower filtration resistance, better flux, and higher flux recovery ratio than the pristine membrane. Salinity, pH, and lactose concentration are determinant factors that affect filtration resistance and rejection performance during the ultrafiltration of dairy wastewater. Generally, higher irreversible and total resistances and slightly lower chemical oxygen demand (COD) rejections were found at higher salinity (expressed by electric conductivity values of >4 mS/cm) than lower salinity (<4 mS/cm) levels. The presence of lactose in dairy wastewater increased irreversible resistance and severely reduced COD rejection during ultrafiltration due to the ability of lactose to pass through the membranes. It was ascertained that membranes require further treatment after filtrating such wastewater. Lower resistances and slightly better COD rejections were observed at pH 7.5 and pH 9.5 compared to those observed at pH 4. Photocatalytic membranes fouled during the ultrafiltration of real dairy wastewater were regenerated by visible light irradiation. The membrane containing all constituents (i.e., TiO₂, carbon nanotubes, and BiVO₄) showed the best regeneration performance, exceeding that of the pristine membrane by 30%. Full article

The shuttling effect of soluble lithium polysulfides (LiPSs) and the sluggish conversion kinetics of polysulfides into insoluble Li₂S₂/Li₂S severely hinders the practical application of Li-S batteries. Advanced catalysts can capture and accelerate the liquid–solid conversion of polysulfides. Herein, we try to make use of bismuth tantalum oxide with oxygen vacancies as an electrocatalyst to catalyze the conversion of LiPSs by reducing the sulfur reduction reaction (SRR) nucleation energy barrier. Oxygen vacancies in Bi₄TaO₇ nanoparticles alter the electron band structure to improve instinct electronic conductivity and catalytic activity. In addition, the defective surface could provide unsaturated bonds around the vacancies to enhance the chemisorption capability with LiPSs. Hence, a multidimensional carbon (super P/CNT/Graphene) standing sulfur cathode is prepared by coating oxygen vacancies Bi₄TaO_7−x nanoparticles, in which the multidimensional carbon (MC) with micropores structure can host sulfur and provide a fast electron/ion pathway, while the outer-coated oxygen vacancies with Bi₄TaO_7−x with improved electronic conductivity and strong affinities for polysulfides can work as an adsorptive and conductive protective layer to achieve the physical restriction and chemical immobilization of lithium polysulfides as well as speed up their catalytic conversion. Benefiting from the synergistic effects of different components, the S/C@Bi₃TaO_7−x coin cell cathode shows superior cycling and rate performance. Even under a high level of sulfur loading of 9.6 mg cm⁻², a relatively high initial areal capacity of 10.20 mAh cm⁻² and a specific energy density of 300 Wh kg⁻¹ are achieved with a low electrolyte/sulfur ratio of 3.3 µL mg⁻¹. Combined with experimental results and theoretical calculations, the mechanism by which the Bi₄TaO₇ with oxygen vacancies promotes the kinetics of polysulfide conversion reactions has been revealed. The design of the multiple confined cathode structure provides physical and chemical adsorption, fast charge transfer, and catalytic conversion for polysulfides. Full article

In this study, we examine the effect of integrating different carbon nanostructures (carbon nanotubes, CNTs, graphene nanoplatelets, GNPs) into Ni- and Ni-W-based bi-functional catalysts for hydrocracking of heptane performed at 400 °C. The effect of varying the SiO₂/Al₂O₃ ratio of the zeolite Y support (between 5 and 30) on the heptane conversion is also studied. The results show that the activity, in terms of heptane conversion, followed the order CNT/Ni-ZY5 (92%) > GNP/Ni-ZY5 (89%) > CNT/Ni-W-ZY30 (86%) > GNP/Ni-W-ZY30 (85%) > CNT/Ni-ZY30 (84%) > GNP/Ni-ZY30 (83%). Thus, the CNT-based catalysts exhibited slightly higher heptane conversion as compared to the GNP-based ones. Furthermore, bimetallic (Ni-W) catalysts possessed higher BET surface areas (725 m²/g for CNT/Ni-W-ZY30 and 612 m²/g for CNT/Ni-ZY30) and exhibited enhanced hydrocracking activity as compared to the monometallic (Ni) catalyst with the same zeolite support and type of carbon structure. It was also shown that CNT-based catalysts possessed higher regeneration capability than their GNP-based counterparts due to the slightly higher thermal stability of the CVD-grown CNTs. Full article

Strain-induced internal electric fields present a significant path to boosting the separation of photoinduced electrons and holes. In addition, piezo-induced positive/negative pairs could be released smoothly, taking advantage of the excellent electroconductibility of some conductors. Herein, the hybrid piezo-photocatalysis is constructed by combining debut piezoelectric nanosheets (Bi₄O₅I₂) and typical conductor multiwalled carbon nanotubes (CNT). The photocatalytic degradation efficiency that the hybrid CNT/Bi₄O₅I₂ exhibits was remarkably increased by more than 2.3 times under ultrasonic vibration, due to the piezo-generated internal electric field. In addition, the transient photocurrent spectroscopy and electrochemical impedance measurement reveal that the CNT coating on Bi₄O₅I₂ enhances the piezo-induced positive/negative migration. Therefore, the piezocatalytic activity of CNT/Bi₄O₅I₂ could be improved by three times, compared with pure Bi₄O₅I₂ nanosheets. Our results may offer promising approaches to sketching efficient piezo-photocatalysis for the full utilization of solar energy or mechanical vibration. Full article

This study presents a highly efficient method of a synthesis of n-butyl acrylate via esterification of acrylic acid and n-butanol in the presence of supported ionic liquid phase (SILP) biocatalyst consisting of the lipase B from Candida antarctica (CALB) and multi-walled carbon nanotubes (MWCNTs) modified by D-glucose-based ionic liquids. Favorable reaction conditions (acrylic acid: n-butanol molar ratio 1:2, cyclohexane as a solvent, biocatalyst 0.150 g per 1 mmol of acrylic acid, temperature 25 °C) allowed the achievement of a 99% yield of n-butyl acrylate in 24 h. Screening of various ionic liquids showed that the most promising result was obtained if N-(6-deoxy-1-O-methoxy-α-D-glucopyranosyl)-N,N,N-trimethylammonium bis-(trifluoromethylsulfonyl)imide ([N(CH₃)₃GlcOCH₃][N(Tf)₂]) was selected in order to modify the outer surface of MWCNTs. The final SILP biocatalyst–CNTs-[N(CH₃)₃GlcOCH₃][N(Tf)₂]-CALB contained 1.8 wt.% of IL and 4.2 wt.% of CALB. Application of the SILP biocatalyst led to the enhanced activity of CALB in comparison with the biocatalyst prepared via physical adsorption of CALB onto MWCNTs (CNTs-CALB), as well as with commercially available Novozyme 435. Thus, the crucial role of IL in the stabilization of biocatalysts was clearly demonstrated. In addition, a significant stability of the developed biocatalytic system was confirmed (three runs with a yield of ester over 90%). Full article

A novel graphite-phase carbon nitride (g-C₃N₄)/bismuth ferrite (BiFeO₃)/carbon nanotubes (CNTs) ternary magnetic composite (CNBT) was prepared by a hydrothermal synthesis. Using this material, Cr(VI) and methylene blue (MB) were removed from wastewater through synergistic adsorption and photocatalysis. The effects of pH, time, and pollutant concentration on the photocatalytic performance of CNBT, as well as possible interactions between Cr(VI) and MB species were analyzed. The obtained results showed that CNTs could effectively reduce the recombination rate of electron-hole pairs during the photocatalytic reaction of the g-C₃N₄/BiFeO₃ composite, thereby improving its photocatalytic performance, while the presence of MB increased the reduction rate of Cr(VI). After 5 h of the simultaneous adsorption and photocatalysis by CNBT, the removal rates of Cr(VI) and MB were 93% and 98%, respectively. This study provides a new theoretical basis and technical guidance for the combined application of photocatalysis and adsorption in the treatment of wastewaters containing mixed pollutants. Full article

In this work, ternary all-solid-state Z-scheme g-C₃N₄/carbon nanotubes/Bi₂Fe₄O₉ (g-C₃N₄/CNT/BFO) composites with enhanced photocatalytic activity were prepared by a hydrothermal method. The morphology observation shows that ternary heterojunctions are formed in the g-C₃N₄/CNT/BFO composites. The photocatalytic activity of the samples for the degradation of acid orange 7 was investigated under simulated sunlight irradiation. It was found that the ternary composites exhibit remarkable enhanced photocatalytic activity when compared with bare BFO and g-C₃N₄/BFO composites. The effect of the CNT content on the photocatalytic performance of the ternary composites was investigated. The photocatalytic mechanism of g-C₃N₄/CNT/BFO was proposed according to the photoelectrochemical measurement, photoluminescence, active species trapping experiment and energy-band potential analysis. The results reveal that the introduction of CNT as an excellent solid electron mediator into the ternary composites can effectively accelerate the electron migration between BFO and g-C₃N₄. This charge transfer process results in highly-efficient separation of photogenerated charges, thus leading to greatly enhanced photocatalytic activity of g-C₃N₄/CNT/BFO composites. Furthermore, the g-C₃N₄/CNT/BFO composites also exhibit highly-efficient photo-Fenton-like catalysis property. Full article