Deposition of CuWO4 nanoparticles over g-C3N4/Fe3O4 nanocomposite: Novel magnetic photocatalysts with drastically enhanced performance under visible-light

Novel g-C₃N₄/Fe₃O₄/CuWO₄ nanocomposites, as magnetic visible-light-driven photocatalysts, fabricated through a simple refluxing-calcination process. The synthesized photocatalysts were characterized by a series of techniques including XRD, EDX, SEM, TEM, HRTEM, FT-IR, TGA, BET, UV–vis DRS, PL, and VSM. The results showed that heterojunctions are formed between g-C₃N₄, Fe₃O₄, and CuWO₄, which favor suppression of the photogenerated electron/hole pairs from recombination. The resultant g-C₃N₄/Fe₃O₄/CuWO₄ (30%) sample exhibited superior photocatalytic performance. The degradation rate constants on the g-C₃N₄/Fe₃O₄/CuWO₄ (30%) nanocomposite were almost 10.5, 17, 12.5, and 42.5 times higher than those of the pristine g-C₃N₄ for degradations of RhB, MB, MO, and fuchsine, respectively. Moreover, the photocatalyst was magnetically separated and recycled with negligible loss in the activity, which is important for the sustainable photocatalytic processes. Thus, the ternary nanocomposite could have potential applications in different photocatalytic processes.     

Exceptional photocatalytic activity for g-C3N4 activated by H2O2 and integrated with Bi2S3 and Fe3O4 nanoparticles for removal of organic and inorganic pollutants

Herein, hydrogen peroxide activated graphitic carbon nitride (agCN) was combined with Fe₃O₄ and Bi₂S₃ to fabricate agCN/Fe₃O₄/Bi₂S₃ nanocomposites via facile refluxing method, as visible-light-induced photocatalysts for photodegradations of anionic and cationic dyes such as MO, RhB, MB, and photoreduction of Cr(VI). The fabricated samples were explored by XRD, EDX, XPS, TGA, SEM, TEM, HRTEM, VSM, PL, FT-IR, BET, and UV-vis DRS. Photocatalytic activity of the nanocomposite with 20% of Bi₂S₃ was 16.6, 40.4, 19.5, and 12.5 times more than that of the pristine gCN in removal of RhB, MB, MO, and Cr(VI), respectively. A plausible photocatalytic mechanism on the agCN/Fe₃O₄/Bi₂S₃ nanocomposites was proposed by construction of n-n heterojunction between gCN and Bi₂S₃. Also, stability of the magnetic hybrid was characterized through cyclic photocatalytic tests.     

Fabrication of novel ZnO/MnWO4 nanocomposites with p-n heterojunction: Visible-light-induced photocatalysts with substantially improved activity and durability

We report, for the first time, binary ZnO/MnWO₄ nanocomposites with p-n heterojunction fabricated by a simple ultrasonic-calcination route. The phase structure, morphology, and optical along with textural properties were comprehensively characterized. The photocatalytic performance was studied via degradations of rhodamine B, methyl blue and methyl orange (RhB, MB, MO), and fuchsine pollutants under visible-light illumination. The ZnO/MnWO₄ nanocomposites exhibited better photocatalytic performance than their single components and the nanocomposite with 30?wt% MnWO₄ showed the highest activity. Photocatalytic performance of this nanocomposite is 22.5, 17.7, 26.8, and 23.9 times higher than that of the ZnO sample in degradations of RhB, MB, MO, and fuchsine dyes, respectively. The improved photocatalytic performance was ascribed to the formation of p-n heterojunction between ZnO and MnWO₄ with high charge separation efficiency as well as strong visible-light absorption ability. The possible mechanism for the improved photocatalytic performance was proposed. This study revealed that the novel ZnO/MnWO₄p-n heterojunction can act as a promising visible-light-active photocatalyst for environmental applications.     

Novel ternary g-C3N4/Fe3O4/MnWO4 nanocomposites: Synthesis,characterization, and visible-light photocatalytic performance for environmental purposes

The g-C₃N₄/Fe₃O₄/MnWO₄ nanocomposites were prepared by a refluxing-calcination procedure. Visible-light-induced photocatalytic experiments showed that the g-C₃N₄/Fe₃O₄/MnWO₄ (10%) nanocomposite has excellent ability to degrade a range of contaminants including rhodamine B, methylene blue, methyl orange, and fuchsine, which is about 7, 10, 25, and 31 times of the g-C₃N₄ photocatalyst, respectively. Reactive species trapping experiments revealed that superoxide anion radicals play major role in the photodegradation reaction of rhodamine B (RhB). After the treatment process, the utilized photocatalyst was magnetically recovered and reused with negligible loss in the photocatalytic activity, which is vital in the photocatalytic processes. Finally, a mechanism was proposed for the enhanced interfacial carrier separation and transfer and the improved photocatalytic performance.     

Novel magnetically separable g-C3N4/Fe3O4/Ag3PO4/Co3O4 nanocomposites: Visible-light-driven photocatalysts with highly enhanced activity

In this study, a series of novel quaternary g-C₃N₄/Fe₃O₄/Ag₃PO₄/Co₃O₄ nanocomposites were fabricated. The prepared nanocomposites were characterized by XRD, EDX, SEM, TEM, UV-DRS, FT-IR, PL, TG, and VSM methods to gain insight about structure, purity, morphology, optical, thermal, and magnetic properties. Photocatalytic activity of the samples was investigated under visible-light irradiation by degradations of rhodamine B, methylene blue, methyl orange, and phenol as four organic pollutants. The highest photocatalytic degradation efficiency was observed when the sample calcined at 300 °C for 2 h with 20 wt% of Co₃O₄. The photocatalytic activity of this nanocomposite is almost 16.8, 15.7, 4.6, and 5.1 times higher than those of the g-C₃N₄, g-C₃N₄/Fe₃O₄, g-C₃N₄/Fe₃O₄/Ag₃PO₄ (20%), and g-C₃N₄/Fe₃O₄/Co₃O₄ (20%) samples in photodegradation of rhodamine B, respectively. Finally, on the basis of the energy band positions, the mechanism of enhanced photocatalytic activity was discussed.     

Enhancement of photocatalytic activity and stability of Ag2CO3 by formation of AgBr/Ag2CO3 heterojunction in mordenite zeolite

Two serious problems for semiconductor photocatalysts are their poor photocatalytic activity and low stability. In this work, Ag₂CO₃ nanoparticles incorporated in mordenite zeolite (MOR) by a facile precipitation method. Silver bromide (AgBr) with different weight percentage (20%, 40% and 50%) was coupled into Ag₂CO₃-MOR composite and producing a series of novel AgBr/Ag₂CO₃-MOR nanocomposites. The effects of AgBr on the Ag₂CO₃–MOR catalyst for the photocatalytic degradation of methyl blue (MB) under visible light irradiation have been investigated. The structure, composition and optical properties of nanocomposites were investigated by UV–Visible diffuse reflectance spectroscopy (UV–Vis DRS), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM). The prepared AgBr/Ag₂CO₃-MOR photocatalyst with the optimal content of AgBr (50 wt%) indicated higher photocatalytic activity than that of the Ag₂CO₃-MOR and Ag₂CO₃ for degradation of methylene blue (MB) under visible light irradiation. For studying of stability of nanocomposites, Fe⁺³ ions, as a cheap and available cocatalyst, was inserted into mordenite matrix (Fe³⁺/MOR) by impregnation method. The hybrid material (AgBr/Ag₂CO₃) was synthesized in the Fe³⁺/MOR matrix by precipitation method. The cycle experiments on the AgBr/Ag₂CO₃-Fe/MOR nanocomposite indicated that cocatalyst, not only to improve photocatalytic activity, but also enhance photoinduced stability of photosensitive silver compounds in all cycles with respect to MOR. On the basis of the experimental results, a possible mechanism for the enhanced photocatalytic activity and photoinduced stability of silver compounds by Fe³⁺ cocatalyst was proposed. The mordenite support played an important role in decreases of recombination of photogenerated electrons-holes and increases of MB absorption. The Fe cocatalyst reduced photocorrosion of silver compounds.     

High performance magnetically recoverable g-C3N4/Fe3O4/Ag/Ag2SO3 plasmonic photocatalyst for enhanced photocatalytic degradation of water pollutants

The g-C₃N₄/Fe₃O₄/Ag/Ag₂SO₃ nanocomposites have been successfully fabricated by facile refluxing method. The as-obtained products were characterized by XRD, EDX, SEM, TEM, UV–vis DRS, FT–IR, TGA, PL, and VSM techniques. The results suggest that the Ag/Ag₂SO₃ nanoparticles have anchored on the surface of g-C₃N₄/Fe₃O₄ nanocomposite, showing strong absorption in the visible region. The evaluation of photocatalytic activity indicates that for the g-C₃N₄/Fe₃O₄/Ag/Ag₂SO₃ (40%) nanocomposite, the degradation rate constant was 188 × 10^?4 min^?1 for rhodamine B, exceeding those of the g-C₃N₄ (16.0 × 10^?4 min^?1) and g-C₃N₄/Fe₃O₄ (20.2 × 10^?4 min^?1) by factors of 11.7 and 9.3, respectively. The results showed that the nanocomposite prepared by refluxing for 120 min has the superior photocatalytic activity and its activity decreased with rising the calcination temperature. The trapping experiments confirmed that superoxide ion radical was the main active species in the photocatalytic degradation process. Also, it was demonstrated that the magnetic photocatalyst has considerable activity in degradation of one more dye pollutant. Finally, the reusability of the photocatalyst was evaluated by five consecutive catalytic runs. This work may open up new insights into the utilization of magnetically separable nanocomposites and provide new opportunities for facile fabrication of g-C₃N₄-based plasmonic photocatalysts.     

Oxygen-rich TiO2 decorated with C-Dots: Highly efficient visible-light-responsive photocatalysts in degradations of different contaminants

Providing novel photocatalysts with high photocatalytic efficiency is of great significance. In the present work, hydrogen peroxide and carbon dots (C-Dots) were utilized to enhance the photocatalytic performance of TiO₂ under visible light. The fabricated TiO₂-peroxo/C-Dots photocatalysts were analyzed by XRD, HRTEM, SEM, EDX, BET, FT-IR, XPS, PL, UV–Vis DRS, EIS, and photocurrent density. Photocatalytic abilities of the nanocomposites were evaluated by photocatalytic removal of RhB, MO, MB, fuchsine, and Cr (VI) upon visible-light illumination. The results demonstrated that the binary nanocomposites exhibited remarkably enhanced photocatalytic activity compared with the TiO₂ and TiO₂-peroxo photocatalysts. The best photocatalytic performance was obtained using 0.75?mL of C-Dots, which was approximately 79.2, 17.1, 71.4, and 40.5 times higher than the pure TiO₂ for degradations of RhB, MO, MB, and fuchsine, respectively. Furthermore, the TiO₂-peroxo/C-Dots nanocomposites exhibited high stability in consecutive photocatalytic processes. Based on the results, the TiO₂-peroxo/C-Dots photocatalyst is expected to become a promising photocatalyst for practical applications in water purification.     

g-C3N4 quantum dot decorated MoS2/Fe3O4 as a novel recoverable catalyst for photodegradation of organic pollutant under visible light

In this research, zero-dimensional (quantum dots) of graphitic carbon nitride (g-C₃N₄) and Fe₃O₄ nanoparticles were decorated on MoS₂ nanosheets to prepare MoS₂/Fe₃O₄/g-C₃N₄ quantum dots. Photocatalytic activities of newly synthesized nanocatalyst were investigated by the degradation of methylene blue (MB) and methyl orange (MO) under visible LED lamp light. In these degradation reactions, the parameters effective such as dyes concentration, pH, amount of catalyst, and irradiation time were also investigated. The systematic investigations revealed that 10 mg of MoS₂/Fe₃O₄/g-C₃N₄QDs catalyst was optimum to degrade 10 mg/L of MB and 40 mg of nanocatalyst to degrade 10 mg/L of MO with 60 W of LED irradiation. Nanocomposite can act as an excellent photocatalyst for degradation of MB and MO at short time intervals and also can be easily separated by an external magnet and reused several times. The kinetic data acquired for the degradation of dyes were matched to first-order rate equations, and also the apparent rate constants for the degradation of MB and MO were calculated as follows: K?=?0.285 min^?1 and K?=?0.263 min^?1, respectively. The novelty of catalyst is due to metal (Mo) and non-metal (S) in the structure of substrate (MoS₂), so Fe₃O₄ and g-C₃N₄ QDs can be strongly connected to the substrate. The structure and morphology of prepared nanocomposite were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), scanning electron microscopy (SEM) energy dispersive X-ray spectroscopy (EDS), and UV–Vis spectroscopy.

     

Construction of hybrid g-C3N4/CdO nanocomposite with improved photodegradation activity of RhB dye under visible light irradiation

The hybrid graphitic carbon nitride-cadmium oxide (g-C₃N₄/CdO) nanocomposite was fabricated using chemical precipitation and self-assembly method. The photocatalysts were characterised by XRD, XPS, FTIR, BET, TEM, FESEM, UV-Vis and PL spectroscopy. Based on the optical study, visible light harvesting was improved and the band gap of bulk g-C₃N₄ to hybrid g-C₃N₄/CdO nanocomposite was greatly reduced from 2.72 eV to 2.35 eV, signifying a better charge carrier mobility. The photocatalytic activity were further assessed by conducting rhodamine B (RhB) photodegradation reaction using visible light. An excellent dye removal efficiency of 96% was achieved when 1.5 g/L of hybrid g-C₃N₄/CdO nanocomposite was used with an initial concentration of 10 ppm for 120 min whereas only 66% of RhB was removed by bulk g-C₃N₄ within the same operating conditions. Besides, reusability tests were carried out and evidenced that hybrid g-C₃N₄/CdO nanocomposite can be recycled up to four times by retaining the degradation efficiency. The scavenging studies confirmed that the RhB photodegradation using hybrid g-C₃N₄/CdO nanocomposite was controlled by valance band h⁺ and O²⁻ oxidation reactions. Conclusively, the inclusion of CdO onto g-C₃N₄ resulted in remarkable photocatalytic activity for dye degradation applications.     

Fabrication of Ag<Subscript>3</Subscript>PO<Subscript>4</Subscript>-AgBr-PTh composite loaded on Na<Subscript>2</Subscript>SiO<Subscript>3</Subscript> with enhanced visible-light photocatalytic activity

A novel Ag₃PO₄-AgBr-PTh composite loaded on Na₂SiO₃ was synthesized for enhanced visible-light photocatalytic activity. The photocatalytic activity of the samples was evaluated by photodegrading rhodamine B (RhB) under visible light irradiation. The main reactive species and possible photocatalytic mechanism were also discussed. As a result, the Ag₃PO₄-AgBr-PTh composite loaded on Na₂SiO₃ exhibited enhanced photocatalytic activity for RhB compared with Ag₃PO₄ under visible-light irradiation. Additionally, it was demonstrated that the hole (h⁺) and superoxide radical (?O ₂ ^? ) were the major reactive species involving in the RhB degradation. PTh played vital role for the enhanced photocatalytic activity of Ag₃PO₄-AgBr-PTh-Na₂SiO₃ composite, which offered an electron transfer expressway and accelerated the transfer of the electrons from the CB of AgBr into Ag₃PO₄. This work could provide a new perspective for the synthesis of Ag₃PO₄-based composites and the improvement of photocatalytic activity of Ag₃PO₄.     

Synthesis of porous Fe3O4/g-C3N4 nanospheres as highly efficient and recyclable photocatalysts

A facile approach for the preparation of Fe₃O₄/g-C₃N₄ nanospheres with good porous structure has been demonstrated by a hydrothermal method. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible light (UV–vis) absorbance spectra and X-ray photoelectron spectroscopy (XPS). The photocatalytic decomposition of methyl orange (MO) by the as-prepared samples was carried out under visible light irradiation. The reusability and magnetic properties were also investigated. The results revealed that the porous Fe₃O₄/g-C₃N₄ nanospheres showed considerable photocatalytic activity, and exhibited excellent reusability and magnetic properties with almost no change after five runs.     

Synthesis of Z-scheme g-C3N4/Gd-doped Bi2WO6 heterojunction with enhanced visible-light photodegradation of organic dyes

Herein, we prepared the g-C₃N₄/Gd-doped Bi₂WO₆ Z-scheme heterojunction (BCN) composites by a simple hydrothermal method. The composites were investigated by SEM (EDX), TEM, XRD, XPS, UV–Vis DRS and PL analysis. The photocatalytic performance of composites was envaulted by degrading methylene blue (MB) under the irradiation of a 300 W mercury lamp. The results demonstrated that coupling g-C₃N₄ and doping Gd ³⁺ effectively enhanced the photocatalytic efficiency of pure Bi₂WO₆. The 92% of MB was degraded within 120 min by optimal 0.15–100 BCN sample, being 1.61 times as that of Bi₂WO₆. The greatly enhanced performance of 0.15–100 BCN was due to the synergistic effect of Gd ³⁺ doping and g-C₃N₄ coupling, which maintained high redox capacity. According to the experiment of capture active species, Z-scheme charge transfer mechanism was also deduced. This study may provide an efficient and green method for the treatment of dyestuff industrial wastewater.

     

A facile decoration of anatase Fe3O4/TiO2 nanocomposite with graphene quantum dots: Synthesis,characterization, and photocatalytic activity

A combination of electron-rich graphene quantum dots (GQDs) with Fe₃O₄/TiO₂ nanocomposites may develop an efficient electron transfer for enhanced photocatalytic activity. In this report, a facile decoration of GQDs with maltose precursor was synthesized and loaded onto magnetic anatase TiO₂ nanocomposites under hydrothermal methods. The as-synthetized magnetic TiO₂/GQDs nanocomposite resulted in a specific surface area of 38.00 m²/g and a total pore volume of 0.186 cm³/g. The HRTEM images showed a lattice plane distance of 0.350 nm related to the interplanar spacing of the anatase TiO₂ (1 0 1) plane and that of 0.299 nm observed for the in-plane lattice part of GQDs. The effects of magnetic loading ratio and GQDs loading onto TiO₂, pH, photocatalyst dosage, and methylene blue (MB) concentration were thoroughly evaluated to find the optimum conditions of mineralization MB for getting the highest photocatalytic efficiency. The removal efficiency of around 86.08 ± 3.62% was obtained at pH11, photocatalytic dose 400 mg/100 mL, and MB concentration 10 mg/L. Moreover, the photogenerated electron transfers and MB degradation mechanism by the resulting Fe₃O₄/TiO₂/GQD_S under irradiation of UVA light are proposed. The as-synthesized material improved meaningfully greater photocatalytic efficiency for degrading MB under UVA light irradiation than merely pure anatase TiO₂. Also, the predominant mechanism of MB degradation was direct oxidative decomposition through the photogenerated holes. The photocatalytic destruction of MB complied with the apparent first-order models under UVA light irradiation.     

SnO2/g-C3N4 photocatalyst with enhanced visible-light photocatalytic activity

Visible light-responsive SnO₂/g-C₃N₄ nanocomposite photocatalysts were prepared by ultrasonic-assisting deposition method with melamine as a g-C₃N₄ precursor. The as-prepared photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, UV–vis diffuse reflectance spectroscopy, Fourier transform infrared spectra and photoluminescence emission spectra. The photocatalytic activities of the samples were evaluated by monitoring the degradation of methyl orange solution under visible light irradiation (wavelength ≥400 nm). The results show that the SnO₂ nanoparticles with the size of 2–3 nm are dispersed on the surface of g-C₃N₄ evenly in SnO₂/g-C₃N₄ nanocomposites. The visible-light photocatalytic activity of SnO₂/g-C₃N₄ nanocomposites is much higher than that of pure g-C₃N₄, and increases at first and then decreases with the increment of the content of g-C₃N₄ in the nanocomposites. The visible-light photocatalytic mechanism of the investigated nanocomposites has been discussed.     

Synthesis of β–NaYF4: Yb3+, Tm3+ @ TiO2 and β–NaYF4: Yb3+, Tm3+ @ TiO2 @ Au nanocomposites and effective upconversion–driven photocatalytic properties

The β–NaYF₄: Yb³⁺, Tm³⁺ @ TiO₂ nanocomposite has been prepared by a facile hydrothermal method followed by the hydrolysis of TBOT, and then NaYF₄: Yb³⁺, Tm³⁺ @ TiO₂, HAuCl₄ and sodium citrate were put into an oil bath for reaction to obtain the β–NaYF₄: Yb³⁺, Tm³⁺ @ TiO₂ @ Au core–shell nanocomposite. XRD and HRTEM show that the samples exhibit the hexagonal phase NaYF₄, anatase TiO₂ and cubic Au, indicating that the core–shell phases of NaYF₄−TiO₂ or NaYF₄−TiO₂−Au coexist in these samples. EDS and XPS results show the presence of Na, Y, F, Ti, O and Au elements. When TiO₂ was coated on the surface of upconversion nanomaterials of NaYF₄: Yb³⁺, Tm³⁺, the photocatalytic activity was improved significantly, and the β–NaYF₄: Yb³⁺, Tm³⁺ @ TiO₂ nanocomposite gives the highest photodegradation efficiency for MB and RhB, and decomposes about 73% of MB or 80% of RhB within 4.5 h under simulated solar light irradiation respectively. When the ultraviolet light from simulated sunlight irradiation was removed by the addition of a UV filter, the β–NaYF₄: Yb³⁺, Tm³⁺ @ TiO₂ nanocomposite decomposes about 42% of MB or 48% of RhB within 4.5 h. It means that the upconversion–driven photocatalytic performance (decomposes 42% of MB or 48% of RhB) is more effective than UV light–driven photocatalytic performance (31% of MB or 32% of RhB) in the photodegradation process. In addition, the β–NaYF₄: Yb³⁺, Tm³⁺ @ TiO₂ @ Au core–shell nanocomposite does not exhibit the better photocatalytic activity, and the optimal research will be carried out in the future.     

Enhancement of photocatalysis performance of CdIn2S4/g-C3N4 heterojunction by H2O2 synergism

A highly efficient binary CdIn₂S₄/g-C₃N₄ heterojunction photocatalyst was synthesized by a simple wet impregnation method. Photocatalytic system based on the synergistic action of binary CdIn₂S₄/g-C₃N₄ heterojunction and H₂O₂ was proposed to improve the degradation effect of dyes. The photocatalytic activity was evaluated by the degradation of methyl orange(MO) under visible light irradiation. The results demonstrated that contrasted to pure g-C₃N₄, the synthesized heterojunction can significantly improve the photocatalytic activity. After 120 min of irradiation by visible light, the photocatalytic efficiency of MO degradation of 7CIS/CN was 3.13 times higher than that of g-C₃N₄. When 60 mM H₂O₂ was added on this basis, the photocatalytic efficiency increased from 93.81 to 99.40%. The improvement of photocatalytic activity is attributed to the formation of binary CdIn₂S₄/g-C₃N₄ heterojunction to promote the transfer of photogenerated electron-hole pairs, and an appropriate amount of H₂O₂ as an electron trap further reduced the recombination rate of photogenerated electron-hole pairs. Active species capture experiments showed that ·O₂^? are the main active substances. Subsequently, the mechanism of photocatalytic degradation was proposed. This work provided a new efficient strategy for the degradation of industrial dye wastewater.

     

Enhanced photocatalytic degradation of industrial dye by g-C3N4/TiO2 nanocomposite: Role of shape of TiO2

The photocatalytic degradation of toxic dyes has brought a new revolution to reduce water pollution. To degrade industrial dyes, TiO₂ is an important photocatalyst but the role of morphology is also important in degradation. We have synthesized g-C₃N₄/TiO₂ nanocomposite (1:1) having different shapes of TiO₂ (nanorods (NR), nanospheres (NS), and nanotubes (NT)), to show the effect of morphology on its photocatalytic activity. To improve the photocatalytic efficiency of TiO₂ in visible light, we have incorporated g-C₃N₄, a visible light active photocatalyst. The HRTEM, FESEM and Electron Diffraction studies with color mapping indicate successful synthesis of g-C₃N₄/TiO₂ nanocomposites. The increased photocatalytic efficiency of the nanocomposites regarding the degradation of Rhodamine B (RhB) dye under visible light irradiation is due to the incorporation of g-C₃N₄ with different shapes of TiO₂. The studies show that, the shape of TiO₂ has a remarkable effect in photodegradation. The best degradation performance (～97%) was obtained from g-C₃N₄/TiO₂ -nanotubes composite with a rate constant of 0.0403?min^?1 within 80?min, whereas degradation efficiency of other shapes of TiO₂ like NS (92%) and NR (94.5%) were also found to be greater than that of commercial TiO₂ (P25) composite (74%). Results from UV–Vis absorption study, X-ray Diffraction studies, X-ray photoelectron spectroscopy and BET analysis suggest that the improvement in photocatalytic activity of composite is due to increased light absorption in visible region and increase in surface area (137.1?m²/g). Results from different scavengers study (DMSO, ascorbic acid and methanol) indicate that electron and superoxide ions act as main reactive species in photodegradation of RhB dye. The reusability efficiency of the catalyst shows 86% degradation after 5 consecutive cycles. The effect of pH and catalyst concentration was also determined which shows that maximum degradation occurs at pH?～?7 (98%) and degradation efficiency is increased with increase of catalyst dose from 0.1?mg/ml to 0.6?mg/ml and after that saturation occur due to increase in opacity and scattering of light. A comparative study was done with literature which suggests that this nanocomposites act as one of the best photocatalysts for degradation of toxic dyes.     

Green gelatin-assisted: Synthesis of Co3O4NPs@rGO nanopowder for highly efficient magnetically separable methylene orange dye degradation

GO and Co(NO₃)₂ were respectively used as rGO and Co₃O₄ precursors for preparing magnetically separable Co₃O₄NPs attached Co₃O₄NPs@rGO nanocomposites by a straightforward sol–gel technique. To characterize the nanocomposite materials, FESEM, EDX, elemental mapping, XRD, FTIR, Raman spectroscopy, UV–vis, VSM and BET were employed. When exposed to UV rays, the nanocomposite showed extraordinary photocatalytic degradation of MO dye. According to the measurements of photocatalytic activity, the highly efficient photocatalytic efficiency of the nanocomposite could be attributed to preventing electron-hole recombination by highly effective electron transfer between rGO and semiconductor NPs. The nanocomposite succeeded in the efficient degradation of MO dye, even after five photocatalytic cycles.     

Preparation of visible light responsive g-C3N4/H-TiO2 Z-scheme heterojunction with enhanced photocatalytic activity for RhB degradation

The development of high-efficiency heterojunction with improved photocatalytic property is regarded as a promising way to decontaminate wastewater. In this study, Z-Scheme g-C₃N₄/H-TiO₂ heterojunctions with different proportions were synthesized. The photocatalytic degradation of rhodamine B (RhB) was studied under visible light irradiation. Among them, 10% g-C₃N₄/H-TiO₂ photocatalyst had the best performance, and the degradation rate of RhB was 65% within 120 min. In addition, 10% g-C₃N₄/H-TiO₂ photocatalyst had high stability, and its photocatalytic activity did not decrease significantly after four cycles. Through photocurrent analysis, it is found that the photogenerated carriers have obviously excellent separation and transfer characteristics, which makes the 10% g-C₃N₄/H-TiO₂ photocatalyst have good degradation performance. Electron paramagnetic resonance (ESR) experiments showed that ·OH and ·O₂^? were active radicals during degradation.