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2 results on '"WO3-x@mesoporous carbon"'

1. Synthesis of N-Doped Magnetic WO3–x@Mesoporous Carbon Using a Diatom Template and Plasma Modification : Visible-Light-Driven Photocatalytic Activities

Author

Behrouz Vahid, Alireza Khataee, Peyman Gholami, Amit Bhatnagar, and Department of Chemistry

Subjects
WO3-x@mesoporous carbon, Materials science, Band gap, 116 Chemical sciences, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, Photochemistry, 01 natural sciences, General Materials Science, Hydrogen production, Nanocomposite, nitrogen doping, reduced tungsten oxide, 021001 nanoscience & nanotechnology, beta-lactam antibiotics degradation, 0104 chemical sciences, hydrogen evolution, chemistry, plasma modification, 13. Climate action, Photocatalysis, Degradation (geology), Nanorod, 0210 nano-technology, Carbon, Visible spectrum
Abstract

Synthesis of three-dimensional photocatalysts offers great potential for chemical conversion and hydrogen generation as appropriate solutions for environmental protection and energy shortage challenges. In this study, the magnetic WO3–x@mesoporous carbon (M-WO3–x@MC) was synthesized through the evaporation-induced self-assembly method applying diatom frustules as a natural template. Then, plasma modification was used to prepare the N-doped M-WO3–x@MC (NM-WO3–x@MC) with enhanced photocatalytic activity and durable performance. The WO3–x was embedded in the conductive MC, which was also partially reduced by the carbon precursor within the heat-treatment procedure. The obtained M-WO3–x@MC was treated by the plasma under an N2 atmosphere for the production of the final photocatalyst containing both the N-doped WO3–x and MC. As a result, the NM-WO3–x@MC had larger surface area (208.4 m2 g–1), narrower band gap (2.3 eV), more visible light harvesting, and confined electron–hole pairs recombination. The H2 generation rates of net WO3 nanorods and NM-WO3–x@MC nanocomposite were estimated as 532 and 2765 μmol g–1 h–1, respectively. Additionally, more than 90% of antibiotics (cephalexin, cefazolin and cephradine) degradation and 76% of total organic carbon elimination were obtained after 120 and 240 min of photocatalytic process under visible light irradiation. Eventually, more than eight intermediates were detected for each antibiotic degradation using the gas chromatography–mass spectrometer method, and based on the obtained results, the possible degradation pathways were suggested.

Published
2021

2. Photocatalytic degradation of antibiotic and hydrogen production using diatom-templated 3D WO3-x@mesoporous carbon nanohybrid under visible light irradiation.

Author

Gholami, Peyman, Khataee, Alireza, and Bhatnagar, Amit

Subjects
*TUNGSTEN, *VISIBLE spectra, *HYDROGEN production, *INTERSTITIAL hydrogen generation, *ELECTRON paramagnetic resonance, *BAND gaps, *DIATOM frustules
Abstract

Synthesis of highly efficient 3D photocatalysts offers unique abilities for hydrogen production and chemical conversion to find a solution for energy shortage and environmental pollution issues. However, current strategies for production of ordered nanohybrid photocatalysts usually involve complex procedures and the use of expensive templates, which limit their practical applications. In this work, 3D WO 3-x @mesoporous carbon photocatalyst was fabricated through one-pot evaporation-induced self-assembly (EISA) process using Cyclotella sp. as natural template. During heat-treatment, the precursor of carbon could partially reduce tungsten oxide under N 2 atmosphere leading to the embedding of WO 3-x in conductive mesoporous carbon structure. The diatom templated WO 3-x @mesoporous carbon (DT-WO 3-x @MC) nanohybrid exhibited high surface area (195.37 m2 g−1) and narrowed band gap (2.67 eV). Integration of tungsten oxide with mesoporous carbon and formation of oxygen vacancies enhanced the absorption of visible light using DT-WO 3-x @MC and limited the recombination of electron-hole pairs. 98.7% of cefazolin (CFZ) degradation efficiency and 85.5% of total organic carbon (TOC) removal efficiency were observed within 90 and 180 min under visible light irradiation, respectively. Scavenger quenching tests and electron spin resonance (ESR) analysis demonstrated that O 2 • − played a main role in photocatalysis. CFZ degradation pathway was proposed via identification of conversion intermediates using GC-MS analysis. Photocatalytic hydrogen production rates of the pure WO 3 and the DT-WO 3-x @MC nanohybrid were determined as 746 and 1851 μmol g−1 h−1, respectively. This study presented a way to develop a high-performance and stable photocatalyst using diatom frustules as natural template which works under practical conditions for environmental remediation and energy production. Evaporation-induced self-assembly synthesis of WO 3-x @MC nanohybrid using diatom template for photocatalytic H 2 production and water treatment. Image 1 • Synthesis of 3D reduced tungsten oxide@mesoporous carbon using diatom template. • Superior photocatalytic properties of synthesized nanohybrid compared to pure WO 3. • Photocatalytic cefazolin degradation and H 2 production using synthesized nanohybrids. • Reusability of tungsten oxide@mesoporous carbon photocatalyst after five cycles. • A possible pathway for cefazolin photodegradation. [ABSTRACT FROM AUTHOR]

Published
2020
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