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Domestic wastage and liquid discharge from industries cause serious water pollution and severely damage the life cycle of living species. Therefore, it is necessary to construct efficient photocatalysts for the removal of toxic pollutants from water. Herein, a novel heterostructure ZnWO–ZnCeS nanocomposite was prepared by the sol-gel route and studied its physical and photocatalytic properties using various analytical techniques. Under sunlight irradiation, the ZnWO–ZnCeS photocatalyst eliminated 99.7, 99.1, 99.0 % rhodamine-B (RhB), methylene blue (MB), and safranin-O (SO) dyes within 70 min with excellent performance higher than individual ZnWO and ZnCeS catalysts. The optimization tests exhibit the catalyst loading = 30 mg, dye content = 25 ppm, solution pH = 8 of ZnWO–ZnCeS against MB dye for practical application. The heterojunction of coupled ZnWO and ZnCeS leads to a synergistic effect that facilitates the charge transport and hampers the recombination of photo-induced charge carriers thereby leading to boosted photocatalytic performance. Furthermore, based on the scavenging test, the hydroxyl and superoxide radicals were the reactive species during the photodegradation reaction. The designed photodegradation reaction mechanism has proposed the formation of an S-scheme in ZnWO–ZnCeS that led to the accumulation of electrons at ZnCeS and holes at ZnWO, favoring the formation of reactive species for dye degradation. Moreover, this work provides a novel direction to synthesize S-scheme heterostructure photocatalysts for application in wastewater treatment. [Display omitted] • Construction of novel S-scheme ZnCeS–ZnWO heterostructure photocatalyst. • The effect of catalyst dose, pH, dye concentration, and reusability were studied. • Enhanced electron transfer/separation was achieved via direct contact S-scheme. • •O 2 − and •OH dominated for MB, SO, and RhB dyes degradation under direct sunlight. • Robust and durable photocatalyst designed for application in wastewater treatment. [ABSTRACT FROM AUTHOR]

In this work, tri-phase direct dual S-scheme ZnO–V 2 O 5 –WO 3 heterostructured nanocomposite and pure ZnO, V 2 O 5 , and WO 3 nanoparticles were synthesized by using a facile co-precipitation approach to investigate antibacterial and photocatalytic characteristics of the grown nanocomposite. The physical properties of as-synthesized products were examined by employing characterization techniques such as Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman, Fourier transform infrared spectroscopy (FTIR), and UV–vis spectroscopy. The XRD results confirmed the formation of pristine ZnO, V 2 O 5 , WO 3 nanoparticles and the existence of diffraction peaks related to hexagonal phase ZnO, orthorhombic V 2 O 5 , and monoclinic phase of WO 3 in ZnO–V 2 O 5 –WO 3 nanocomposite. The variation in structural parameters was studied by SSP, Scherrer plot, and W–H models. The energy bandgap of nanocomposite (2.63 eV) was calculated from UV–vis spectroscopy, which indicated the usability as a photocatalyst under direct sunlight. FTIR and Raman's spectra also supported the formation of the ZnO–V 2 O 5 –WO 3 nanocomposite. Spherical and roughly hexagonal morphology were seen in SEM images. EDX analysis has confirmed the existence of Zn, V, W, and O in the nanocomposite. The antibacterial test against Klebsiella pneumonia, Staphylococcus aureus , Proteus Vulgaris, and Pseudomonas aeruginosa bacteria showed higher activity. The photocatalytic performance of the ZnO–V 2 O 5 –WO 3 nanocomposite (99.8%) was the highest against methylene blue (MB) as compared to pure ZnO (78.8%), V 2 O 5 (85.8%), and WO 3 (80.0%) under natural sunlight. The degradation efficiency of ZnO–V 2 O 5 –WO 3 against cresol red (CR), rhodamine-B (RhB), methyl orange (MO), safranin-O (SO), and methyl red (MR) dyes was 67.0%, 86.6%, 98.0%, 76.8%, and 99.0%, respectively, under direct sunlight in 80 min. Different schematic models are designed to illustrate the photocatalytic reaction mechanism, whereas the separation of charge carriers and enhanced photocatalytic performance can be efficiently explained by S-scheme. [Display omitted] • Facile synthesis of tri-phase direct dual S-scheme ZnO–V 2 O 5 -WO 3 heterostructured NC and pure ZnO, V 2 O 5 , and WO 3 NPs. • SEM, EDX, XRD, Raman, FTIR, and UV–vis was carried out. • The photocatalytic performance was tested against MB, CR, RhB, MO, SO, and MR dyes. • S-scheme is more efficient than other schemes for enhancing photocatalytic activity. • The antibacterial test against different bacteria strain was performed. [ABSTRACT FROM AUTHOR]

Novel direct dual Z-scheme ZnO-Er 2 O 3 -Nd 2 O 3 @rGO heterostructured nanocomposite along with simple ZnO-Er 2 O 3 -Nd 2 O 3 nanocomposite was prepared by co-precipitation route. The X-ray diffraction pattern exhibited the diffraction peaks associated with ZnO (hexagonal), Er 2 O 3 (cubic), and Nd 2 O 3 (hexagonal) in both nanocomposites. The FTIR spectra further confirmed the formation of nanocomposites. The energy bandgap of simple and rGO decorated nanocomposites were 3.1 and 2.82 eV. The antibacterial characteristics of grown samples showed that the rGO anchored nanocomposite has higher antibacterial activity as compared to simple nanocomposite. The ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite exhibited higher photodegradation (97.0%) against methylene blue (MB) than simple nanocomposite (86.0%). The effectiveness of grown ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite as photocatalyst was also tested for degradation of other dyes such as RhB, MO, CR, and SO. The effect of operating parameters was investigated for ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite. A possible conventional heterojunction and Z-scheme for the degradation using ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite has been designed to elucidate the photocatalytic mechanism. • ZnO-Er 2 O 3 -Nd 2 O 3 and ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposites successfully prepared. • The photocatalytic application was studied using MB, RhB, MO, CR and SO dyes. • The effect of operating parameters for the degradation of SO dye investigated. • The antibacterial activity against different bacterial strains was investigated. [ABSTRACT FROM AUTHOR]

Developing effective and noble-metal-free electrocatalysts for the grim oxygen evolution reaction (OER) and photocatalysts for pollutant elimination is critical for long-term energy supply and environmental remediation. Herein a simple sol-gel technique is used to synthesize NiO/C60 electrophotocatalyst and is characterized via different state-of-art techniques. All the characteristic analytical studies have discovered that the structural components dramatically increased the OER and photocatalytic activity for grown NiO/C60 nanocomposite. TEM results showed that the C60 uniformly covering NiO has a particle size of 46 nm. NiO/C60 electrocatalyst has outperformed the overpotential of 310 mV at a current density of 10 mA/cm2. At the applied voltage, electrochemical impedance spectroscopy showed that the catalytically active surfaces of NiO/C60 and charge transfer rate are much greater than simple NiO. It was also discovered that the grown nanocomposite remained stable for 30 h without degrading, outlasting numerous recent noble-metal-free electrocatalysts. In addition, the NiO/C60 has also exhibited excellent photocatalytic reduction efficiency for Methylene blue (MB) dye and completely degraded after 40 min under sunlight with the stability of up to six cycles. Our findings show that NiO-based water oxidation electrocatalysts and efficient photocatalysts may now be produced at a low cost with outstanding performance. Recycleable core-shell NiO/C60 photocatalyst and electrocatalyst. [Display omitted] • Development of NiO/C60 core-shell electrocatalyst/photocatalyst. • Lower overpotential 310 mV and Tafel slope 43 mV/dec at 10 mA/cm2 for OER. • Complete MB dye degradation in 40 min under natural sunlight. • Remarkable stability 1500 cycles for OER and 6 cycles for photocatalysis. • Dual-functional, low-cost, noble-metal-free catalyst with outstanding performance. [ABSTRACT FROM AUTHOR]

Abstract: A magnetically separable single-phase MgFe2O4 photocatalyst with a spinel crystal structure was synthesized by using the solid-state reaction method. The formation of spinel structure is confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. The magnetic measurements showed that the photocatalyst material can be separated from water when an external magnetic field is added and redispersed into water solution after the external magnetic field is eliminated. It is one of the promising photocatalysts for waste water treatment. The photocatalytic activity of MgFe2O4 was investigated by using the photo-decomposition of methylene blue dye under visible light. The photoelectrochemical property of the MgFe2O4 was studied by measuring their photocurrent–potential behavior in 1 M NaOH electrolyte under AM 1.5100 mW cm−2 illumination. [Copyright &y& Elsevier]

Structural, magnetic, optical and electronic properties of GeGa 2 O 4 , CoGa 2 O 4 , GeCo 2 O 4 and CoCo 2 O 4 spinel oxides have been studied. Spinel oxides are studied by performing theoretical calculations based on density functional theory. In non-magnetic host GeGa 2 O 4 spinel oxide, significant effects of Co occupancy (at A, B and/or both sites) on the electronic, magnetic and optical behavior have been observed. Among the spinel oxides, the CoGa 2 O 4 , GeCo 2 O 4 and CoCo 2 O 4 spinel oxides show 100% spin-polarization and exhibit stable cubic structure in ferromagnetic phase. The calculated structural and magnetic parameters predict the cation distribution at A and B sites as follows: (G e 2 + ) [ G a 2 3 + ] O 4 − 2 , (C o 2 + ) [ G a 2 3 + ] O 4 − 2 , (G e 4 + ) [ C o 2 2 + ] O 4 − 2 and (C o + 2 ) [ C o 2 3 + ] O 4 − 2 for GeGa 2 O 4 , CoGa 2 O 4 , GeCo 2 O 4 and CoCo 2 O 4 spinel oxides, respectively. The electronic band gap is found to be decreased from 1.605 eV to 0.762 eV for spin↑ state while it is decreased from 1.578 eV to 0.000 eV for spin↓ state with Co occupancy in host GeGa 2 O 4 lattice. Lattice constant decreases (8.7877 Å to 8.1390 Å) as Co occupies B site and/or both (A and B) sites. For GeCo 2 O 4 spinel oxide, the calculated value of total magnetic moment (m tot = 6.12 μ B / f.u) and saturation magnetization (M S = 134.22 emu/g) is found to maximum. Optical properties reveal that the CoGa 2 O 4 , GeCo 2 O 4 and CoCo 2 O 4 spinel oxides have less threshold electronic transition energy relative to host GeGa 2 O 4 spinel oxide. Electronic, magnetic and optical characteristics show potential integration of these spinel oxides in magnetic-semiconducting devices. Image 1 • Effects of Co occupancy on different atomic sites in GeGa 2 O 4 spinel are studied. • Cubic CoGa 2 O 4 , GeCo 2 O 4 and CoCo 2 O 4 spinel oxides show 100% spin-polarization. • Co occupying A, B or both sites decreases the electronic and optical band gap. • GeCo 2 O 4 spinel oxide shows half metallic behavior with m t o t = 6.12 μ B / f.u and M S = 134.22 emu/g. • All spinel oxides show maximum absorption and optical conductivity in UV region. [ABSTRACT FROM AUTHOR]