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In order to solve the problems of powder g-C3N4 catalysts being difficult to recycle and prone to secondary pollution, floating network porous-like sponge monolithic structure g-C3N4 (FSCN) was prepared with a one-step thermal condensation method using melamine sponge, urea, and melamine as raw materials. The phase composition, morphology, size, and chemical elements of the FSCN were studied using XRD, SEM, XPS, and UV–visible spectrophotometry. Under simulated sunlight, the removal rate for 40 mg·L−1 tetracycline (TC) by FSCN reached 76%, which was 1.2 times that of powder g-C3N4. Under natural sunlight illumination, the TC removal rate of FSCN was 70.4%, which was only 5.6% lower than that of a xenon lamp. In addition, after three repeated uses, the removal rates of the FSCN and powder g-C3N4 samples decreased by 1.7% and 2.9%, respectively, indicating that FSCN had better stability and reusability. The excellent photocatalytic activity of FSCN benefits from its three-dimensional-network sponge-like structure and outstanding light absorption properties. Finally, a possible degradation mechanism for the FSCN photocatalyst was proposed. This photocatalyst can be used as a floating catalyst for the treatment of antibiotics and other types of water pollution, providing ideas for the photocatalytic degradation of pollutants in practical applications.

Single-walled carbon nanotube (SWCNT) transparent conducting films (TCFs) are attracting increasing attention due to their exceptional optoelectronic properties. Toluene is a proposed carbon source for SWCNT synthesis, but the growth parameters of SWCNTs and their TCF optoelectronic performance (i.e., sheet resistance versus transmittance) have been insufficiently evaluated. Here, we have for the first time reported a systematic study of the fabrication of high-performance SWCNT TCFs using toluene alone as the carbon source. The mechanisms behind each observed phenomenon were elucidated using optical and microscopy techniques. By optimizing the growth parameters, high yields of SWCNT TCFs exhibiting a considerably low sheet resistance of 57 Ω/sq at 90% transmittance were obtained. This competitive optoelectronic performance is mainly attributable to long SWCNT bundles (mean length is 41.4 μm) in the film. Additionally, a chirality map determined by electron diffraction displays a bimodal distribution of chiral angles divided at 15°, which is close to both armchair and zigzag edges. Our study paved the way towards scaled-up production of SWCNTs for the fabrication of high-performance TCFs for industrial applications.

Solar reforming (SR) is a promising green‐energy technology that can use sunlight to mitigate biomass and plastic waste while producing hydrogen gas at ambient pressure and temperature. However, practical challenges, including photocatalyst lifetime, recyclability, and low production rates in turbid waste suspensions, limit SR's industrial potential. By immobilizing SR catalyst materials (carbon nitride/platinum; CNx|Pt and carbon nitride/nickel phosphide; CNx|Ni2P) on hollow glass microspheres (HGM), which act as floating supports enabling practical composite recycling, such limitations can be overcome. Substrates derived from plastic and biomass, including poly(ethylene terephthalate) (PET) and cellulose, are reformed by floating SR composites, which are reused for up to ten consecutive cycles under realistic, vertical simulated solar irradiation (AM1.5G), reaching activities of 1333 ± 240 µmolH2 m−2 h−1 on pre‐treated PET. Floating SR composites are also advantageous in realistic waste where turbidity prevents light absorption by non‐floating catalyst powders, achieving 338.1 ± 1.1 µmolH2 m−2 h−1 using floating CNx versus non‐detectable H2 production with non‐floating CNx and a pre‐treated PET bottle as substrate. Low Pt loadings (0.033 ± 0.0013% m/m) demonstrate consistent performance and recyclability, allowing efficient use of precious metals for SR hydrogen production from waste substrates at large areal scale (217 cm2), taking an important step toward practical SR implementation. Reusable floating composites of carbon nitride containing hollow glass microspheres separate to the air‐water interface where they catalyze solar reforming (SR) reactions, transforming waste streams to hydrogen gas. Driven by sunlight, the floating composite produces hydrogen gas from plastic and biomass substrates over consecutive cycles and enables SR in turbid waste suspensions, addressing some key concerns for potential application.

Floating immobilized spherical titanium dioxide catalysts were used to degrade micro-pollutants by solar photocatalysis. The degradation of the micro-pollutants was performed in the secondary effluent of a wastewater treatment plant. During the experimental period, the continuous measurement of the solar ultraviolet (UV) radiation intensity was performed. The micro-pollutants were degraded to an average of 55% after 9 h of irradiation. A substance-specific degradation affinity was found, whereby degradation rates varied by a factor of up to 3.5. The substance-specific adsorption behavior was identified as a major limitation of the reaction performance. With an increasing influence of adsorption limitation, the degradation kinetics changed from the pseudo-first order to pseudo-zero order. A correlation between degradation rate and solar irradiance could only be found for substances with high degradation/adsorption affinity. For diclofenac, a 95% degradation rate could be achieved at a radiation dose of approximately 190 mWh/m². The investigated technology represents a promising possibility for a minimally invasive extension of wastewater treatment plants. Possibilities of implication were estimated and discussed within this work, whereby possibilities arise for large-scale as well as decentral treatment plants.

This work studies synthesis of carbon nanotube (CNT) sheet using the high temperature (1400 °C) floating catalyst chemical vapor deposition (FC-CVD) method. Three metallocenes—ferrocene, nickelocene, cobaltocene—and their combinations are used as precursors for metal catalysts in the synthesis process. For the carbon source, an alcohol fuel, a combination of methanol and n-hexane (9:1), is used. First, the metallocenes were dissolved in the alcohol fuel. Then, the fuel mixture was injected into a tube furnace using an ultrasonic atomizer with Ar/H2 carrier gas in a ratio of about 12/1. The synthesis of CNTs from a combination of two or three metallocenes reduces the percentage of metal catalyst impurity in the CNT sheet. However, there is an increase in structural defects in the CNTs when using mixtures of two or three metallocenes as catalysts. Furthermore, the specific electrical conductivity of the CNT sheet was highest when using a mixture of ferrocene and cobaltocene as the catalyst. Overall, the multi-catalyst method described enables tailoring certain properties of the CNT sheet. However, the standard ferrocene catalyst seems most appropriate for large-scale manufacturing at the lowest cost.

The single-stage floating catalyst chemical vapor deposition (SS-FCCVD) method using the ferrocene route (e.g., ferrocene: catalyst and camphor: carbon source) offers significant but largely unexplored versatility for the production of carbon nanotubes (CNTs). Our study used the SS-FCCVD method to grow vertically aligned carbon nanotubes (VACNTs) on an alumina ceramic reactor surface at 850 °C under a nitrogen atmosphere. The experimental setup included a camphor/ferrocene ratio of 20:1 and a specific temperature gradient of 21 °C/cm. To minimize the catalyst agglomeration, we positioned the chemical sources at a distance of 15 cm from the inlet of the CVD reactor. Alumina ceramic surfaces proved highly effective for VACNT production, showing minimal agglomeration of iron particles, facilitating the formation of reactive sites essential for VACNT growth. The VACNTs grew readily on alumina ceramic surfaces, forming bundled, forest-like structures with segment lengths up to 1.2 mm and diameters around 60 nm. When compared to conventional substrates, the surface area of the reaction zone substrate increases by up to 705%, resulting in a significant boost in VACNT yield. A detailed evaluation of characterization results confirmed the growth mechanism and behavior of Fe particles such that carbon-encapsulated particles are attached to the inner and outer surfaces of the CNTs. These VACNT surfaces exhibited superhydrophobic properties, similar to the lotus leaf effect. The synthesized iron-dispersed CNTs exhibit exceptional efficiency in Chromium (VI) removal, with an impressive adsorption capacity of 0.206 mmol/m², positioning them as a promising solution for effective water treatment. This scalable SS-FCCVD method using the ferrocene route achieved the longest VACNTs reported to date.

Perovskite solar cells offer a promising future for next‐generation photovoltaics owing to numerous advantages such as high efficiency and ease of processing. However, two significant challenges, air stability, and manufacturing costs, hamper their commercialization. This study proposes a solution to these issues by introducing a floating catalyst‐based carbon nanotube (CNT) electrode into all‐inorganic perovskite solar cells for the first time. The use of CNT eliminates the need for metal electrodes, which are primarily responsible for high fabrication costs and device instability. The nanohybrid film formed by combining hydrophobic CNT with polymeric hole‐transporting materials acted as an efficient charge collector and provided moisture protection. Remarkably, the metal‐electrode‐free CNT‐based all‐inorganic perovskite solar cells demonstrated outstanding stability, maintaining their efficiency for over 4000 h without encapsulation in air. These cells achieved a retention efficiency of 13.8%, which is notable for all‐inorganic perovskites, and they also exhibit high transparency in both the visible and infrared regions. The obtained efficiency was the highest for semi‐transparent all‐inorganic perovskite solar cells. Building on this, a four‐terminal tandem device using a low‐band perovskite solar cell achieved a power conversion efficiency of 21.1%. These CNT electrodes set new benchmarks for the potential of perovskite solar cells with groundbreaking device stability and tandem applicability, demonstrating a step toward industrial applications. image

An effective and cost-effective approach to synthesize new materials can be determined via research on a carbon nanotube (CNT) aerogel. This review paper gives an overview of the current synthetic methodologies and routes to enhance understanding. It also investigates the appropriate issues on the development of CNT-based three-dimensional (3-D) porous materials in an attempt to fill the knowledge gap regarding viability. First, an elaborate description on CNTs is provided, followed by a focus on CNT macrostructure fabrication, showcasing their key features, disadvantages, advantages and other aspects that were considered as related. Then, the methods for synthesis pertaining to the CNT aerogel are discussed with a focus on a floating catalyst chemical vapour deposition method as well as the growth mechanism pertaining to CNTs employing the method. Key parameters, including catalyst, reaction time, carbon source, carrier gas and reaction temperature, which could cast an impact on the efficiency of the process are discussed subsequently.

Abstract Grapeseed oil as a new source of graphenated carbon nanotube (g-CNTs) hybrids was described in this paper. Mesoporous three-dimensional (3D) g-CNT aerogel was synthesized by a floating catalyst chemical vapor deposition (FCCVD) method. The effect of the H2 gas ratio was evaluated, and the graphenated g-CNTs morphology was identified by various physico-chemical techniques, such as field-emission scanning microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, thermogravimetric analysis (TGA), and N2 sorption studies. Furthermore, the multi-wall carbon nanotube (MWCNT) bundles in the network were highly disordered and rounded by graphene foliate structures in which a large number of sharp edges of graphene sheets were found.

We report a new scheme for fabrication of clean, suspended superconducting weak links from pristine single-walled carbon nanotubes (SWCNT). The SWCNTs were grown using the floating-catalyst chemical vapour deposition (FC-CVD) and directly deposited on top of prefabricated superconducting molybdenum-rhenium (MoRe) electrodes by thermophoresis at nearly ambient conditions. Transparent contacts to SWCNTs were obtained by vacuum-annealing the devices at 900 °C, which enabled proximity-induced supercurrents up to 53 nA. SWCNT weak links fabricated on MoRe/palladium bilayer sustained supercurrents up to 0.4 nA after annealing at relatively low temperature of 220 °C. The fabrication process does neither expose SWCNTs to lithographic chemicals, nor the contact electrodes to the harsh conditions of in situ CVD growth. Our scheme facilitates new experimental possibilities for hybrid superconducting devices.