Synthesis of N-Doped Magnetic WO_3–x@Mesoporous Carbon Using a Diatom Template and Plasma Modification: Visible-Light-Driven Photocatalytic Activities

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 WO 3−x @ mesoporous carbon (M-WO 3−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-WO 3−x @MC (NM-WO 3−x @MC) with enhanced photocatalytic activity and durable performance. The WO 3−x was embedded in the conductive MC, which was also partially reduced by the carbon precursor within the heat-treatment procedure. The obtained M-WO 3−x @MC was treated by the plasma under an N 2 atmosphere for the production of the final photocatalyst containing both the N-doped WO 3−x and MC. As a result, the NM-WO 3−x @MC had larger surface area (208.4 m 2 g −1 ), narrower band gap (2.3 eV), more visible light harvesting, and confined electron−hole pairs recombination. The H 2 generation rates of net WO 3 nanorods and NM-WO 3−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.

Dewetted Silver Nanoparticle-Dispersed WO3 Heterojunction Nanostructures on Glass Fibers for Efficient Visible-Light-Active Photocatalysis by Magnetron Sputtering

“…The other two peaks centered at 712 and 806 cm –1 correspond to the ν(O–W–O) vibrational stretching modes of the monoclinic WO 3 . 47 , 48 The peak at 978 cm –1 in the 2Cu–WO 3 /SGF is attributed to the symmetric stretching mode of W=O bonds resulting from the adsorbing water molecules in the air. 37 Based on group theory calculations, the triclinic CuWO 4 exhibits 36 vibrational modes (Γ Raman+infrared = 18A g + 18A u ).…”

Formation of Aggregate-Free Gold Nanoparticles in the Cyclodextrin-Tetrachloroaurate System Follows Finke–Watzky Kinetics

“…Moreover, the ability of cyclodextrin-capped gold nanoparticles to encapsulate and release various drugs can be used beyond drug delivery. Gold nanoparticles with immobilized cyclodextrins could be used for the sequestration of antibiotics with their subsequent release into the nanocomposite-containing medium for degradation [9,10]. Being reusable and easily separable by centrifugation, these nanoparticles would be useful for the preconcentration step, especially when pH adjustment is needed.…”

Nanoscale Zero-Valent Iron Modified by Bentonite with Enhanced Cr(VI) Removal Efficiency, Improved Mobility, and Reduced Toxicity

“…In recent years, different modified methods have been reported to decrease the agglomeration and improve the mobility and reactivity of nZVI, such as the surface modification (chitosan [13,14], sodium carboxymethyl cellulose [15], starch [16], and polyethylene glycol [17]) and carrier modification (biochar [18], active carbon [19], silica [20], zeolite [21], attapulgite [22], and diatomite [23]). In addition, the modification of reaction conditions such as ultrasound and photocatalysis can also improve the removal efficiency of pollutants [24][25][26]. Bentonite is a widely used porous adsorbent, which has high adsorption capability, chemical and mechanical stability, and unique inter-lamellar structural properties [27].…”