Photocatalytic Degradation Of RhB Research Articles

Design and fabrication of polyaniline/Bi2MoO6 nanocomposites for enhanced visible-light-driven photocatalysis

PANI/Bi2MoO6 composites with improved photoelectrochemical performance and accessible interfacial active sites were fabricated for enhanced visible-light-driven photocatalytic degradation of RhB.

The excellent photocatalytic activity of novel Cs3PW12O40/WO3 composite toward the degradation of rhodamine B

In this paper, a simple one-pot thermal decomposition method was successfully used to synthesize a novel Cs3PW12O40/WO3 composite for the first time. The synthesized composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), FTIR, diffuse reflectance spectroscopy (DRS) and N2 adsorption-desorption techniques. The photocatalytic activity to degrade RhB molecules over Cs3PW12O40/WO3 composite was evaluated under xenon light irradiation. The results indicated the complete degradation of RhB molecules over Cs3PW12O40/WO3 composite after 30 min irradiation. However, the photocatalytic degradation of RhB over WO3 and Cs3PW12O40 after 80 min light irradiation are nearly 52%, and 68%, respectively. The enhanced photocatalytic activity of Cs3PW12O40/WO3 composite compared with WO3, and Cs3PW12O40 was ascribed to the strong interaction between WO3 and Cs3PW12O40, which effectively reduces the recombination of photogenerated electron-hole pairs. Based on experimental results, the possible mechanism of photocatalytic reactions on the Cs3PW12O40/WO3 composite photocatalyst was investigated, and the hydroxyl radical (OH) and superoxide radical (O2−) were determined as the main active species in the photocatalytic degradation of RhB over Cs3PW12O40/WO3 composite.

Atomic layer deposition of fcc-FePt nanoparticles on g-C3N4 for magnetically recyclable photocatalysts with enhanced photocatalytic performance

Graphitic carbon nitride (g-C3N4) was synthesized by a sol-gel method, and fcc-FePt nanoparticles were deposited on g-C3N4 through atomic layer deposition (ALD). The concentration of fcc-FePt was determined by the number of the deposition cycles. The as-synthesized g-C3N4/fcc-FePt composites were characterized by XRD, XPS, and VSM for crystallization, surface chemical states, and magnetic properties. The photocatalytic performance of g-C3N4/fcc-FePt was investigated by photocatalytic degradation of RhB under visible light irradiation. After the reaction, the catalyst was successfully separated from the solution by a magnet. Finally, the stability test showed that g-C3N4/fcc-FePt had a relatively high stability over degradation.

Layered BiOBr/Ti3C2 MXene composite with improved visible-light photocatalytic activity

Layered BiOBr/Ti3C2 (BTC) composites were synthesized by first preparing Ti3C2 nanosheets through the liquid etching of Ti3AlC2 powder and then hybridizing with BiOBr via a facile reflux process. The morphology, crystal structure, light-harvesting capacity, chemical nature of atoms and visible-light photocatalytic degradation activity were systematically studied and discussed. It was found that the introduction of Ti3C2 nanosheets improved UV–Vis light absorption region of BiOBr. A contact interface was formed between BiOBr nanoplate and Ti3C2 nanosheet due to the similar layered structures, which could accelerate the efficient separation and transfer of photoinduced electrons and holes. Thus, the obtained BTC composites showed the higher visible-light photocatalytic activity for the degradation of RhB than pure BiOBr. The generated active species were determined by the active species capture experiment and ESR spectra, showing that ·O2− and ·OH played a crucial role in the photocatalytic degradation of RhB. The corresponding photocatalytic mechanism was proposed. This work may provide a new insight into the construction of earth-abundant MXene-based photocatalysts with high performance and low cost.

Tuning red emission and photocatalytic properties of highly active ZnO nanosheets by Eu addition

Eu-doped ZnO nanosheets were synthesized via a facile and surfactant-free chemical solution deposition method. The detailed characterizations revealed that the as-synthesized samples were well-crystalline which assembled by nanosheets with 25 nm thickness. The Eu ions were successfully doped into the ZnO nanosheets, and the red emissions of Eu3+ ions attributed to the energy of 5D0→7F0, 5D0→7F1 and 5D0→7F2 4f–4f intrashell transitions were observed in PL spectra. The appropriate Eu doping would increase the separation efficiency of electron-hole pairs and promote the formation of the superoxide ions during the photolysis process, which eventually improved the photodegradation of Rhodamine B under UV light irradiation. And the photocatalytic degradation of RhB was also analyzed by a pseudo first order rate. A possible explanation for the modification of bandgap was given based on the modified effect of Eu3+ ions on the electronic structure of ZnO nanosheets, which mainly due to two mechanisms of Burstein-Moss effect and electron-ion/electron scattering.

A novel electrostatic self-assembly method for preparation of TiO2@BiOI photocatalyst

In this work, TiO2@BiOI photocatalyst was successfully fabricated by a novel electrostatic self-assembly method. A series of characterizations were employed to characterize the as-prepared photocatalyst. The potential application and mechanism of this photocatalyst were evaluated and discussed by photocatalytic degradation of RhB. The results showed that the TiO2@BiOI photocatalyst exhibited more excellent photocatalytic performance than pure TiO2. The remarkable enhancement in the photocatalytic activities of the TiO2@BiOI photocatalyst could be attributed to the effective electron–hole separations at the interfaces of the two semiconductors, which facilitated the transfer of the photoinduced carriers. In addition, relative large specific surface area, and appropriate energy band gap have great contribution to the enhancement of photocatalytic performance. In this paper, a new type of photocatalyst was prepared by electrostatic self-assembly method. The photocatalytic performance of the sample was evaluated by various characterization and degradation of RhB. The experimental results show that the photocatalytic activity of the sample is obviously improved.

Enhanced Visible-Light-Responsive Photocatalytic Properties of Bi₂MoO6-BiOCl Nanoplate Composites.

Bi2MoO6-BiOCl nanoplate composites were successfully synthesized by a simple solvothermal process. The morphology, microstructure and optical properties of the as-prepared Bi2MoO6-BiOCl nanocomposites were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-Vis diffuse reflection spectroscopy (DRS). A noteworthy enhancement in the visible-light-responsive photocatalytic degradation of RhB was observed over the Bi2MoO6-BiOCl nanocomposites compared to its individual components. The enhanced photocatalytic performance of Bi2MoO6-BiOCl nanocomposites could be attributed to the heterojunction interface in the composite, which can both efficiently separate photogenerated electron-hole pairs and also restrain the recombination of photoinduced charges.

Facile constructing novel 3D porous g-C3N4/BiOBr0.2I0.8 hybrids: Efficient charge separation for visible-light photocatalysis

In this work, we reported a novel three-dimensional (3D) visible-light-driven hybrid photocatalyst synthesized via a facile hydrothermal process, which consists of two different 2D materials: g-C3N4 and BiOBr0.2I0.8. The physicochemical properties of the as-synthesized 3D hybrid photocatalyst were fully characterized using Electron spin resonance, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and UV–Vis diffuse reflectance spectrometry. The 10CN/BiOBr0.2I0.8 composite exhibits the best performance in visible-light-driven photocatalytic degradation of RhB among prepared samples. In such hybrid systems, electrons generated in g-C3N4 transfer to BiOBr0.2I0.8, while photo-generated holes on BiOBr0.2I0.8 transfer to g-C3N4, which enhances the charge separation through the heterojunction interface. The hole left on the valence band of g-C3N4 is the most efficient active species in the degradation process of RhB, therefore, heterojuncted BiOBr0.2I0.8 need better control for keeping some active sites on g-C3N4. In addition, the photodegradation efficiency of RhB still remains over 98% after six consecutive cycles, which indicates the good stability of such 3D g-C3N4/BiOBr0.2I0.8 hybrid photocatalysts.

Fabrication of BiOI@UIO-66(NH2)@g-C3N4 ternary Z-scheme heterojunction with enhanced visible-light photocatalytic activity

A novel ternary heterojunction BiOI@UIO-66(NH2)@g-C3N4 (BiOI@UNCN) was synthesized by in-situ solvothermal-hydrothermal approach, showing superior photocatalytic degradation of RhB and TC under visible-light irradiation. The optimal BiOI@UNCN-40 composite exhibits the highest degradation efficiency of RhB (95%) in 80 min and TC (80%) in 180 min in comparison with pristine BiOI, UIO-66(NH2) and UIO-66(NH2)@g-C3N4. The improved photocatalytic activity of BiOI@UNCN can be ascribed to its improved visible-light absorption range, the large specific surface area based on UIO-66(NH2) as well as the formation of an effective n-p-n type heterojunction driven by Z-scheme mechanism. The formed Z-scheme mechanism at the interface of ternary composite facilitates the separation and transfer of photoexcited charge carrier, which is confirmed from the results of PL and EIS spectra. The photocatalytic mechanism is further proposed based on the trapping experiment, and the transfer process of photoinduced electron-hole pairs is discussed. This work provides an effective strategy for designing a new ternary photocatalytic system toward degradation of organic pollutants.

Enhanced photocatalytic degradation and UV protection properties of BiOCl nanosheets coating for cotton fabric

BiOCl nanosheets were prepared through a simple solvothermal method. The obtained BiOCl nanosheets were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and UV spectroscopy. The average size of BiOCl nanosheets was 210[Formula: see text]nm. The BiOCl nanosheets were applied as a finishing agent for cotton fabric, which can give the UV protection and photocatalytic degradation of RhB properties to cotton fabric. We made four different concentrations of finishing agents to coat the fabric by pad-dry-cure method. Furthermore, the UPF ratting and photocatalytic degradation of RhB were conducted. The finished cotton fabric exhibited excellent UV protection and photocatalytic property.

Keggin type of polyoxometalate templated assembly of a silver-organic framework with silver-organic cages and helical structures

A new POM-templated metal-organic framework [Ag8L4][PMo12O40]·OH {HL = 5-[4-(1,2,4-triazol-4-yl)phenyl]-1H-tetrazole} containing metal-organic nanocage and left- and right-handed helixes has been isolated under hydrothermal conditions. The Keggin POM plays a template role in the formation of macrocycle and metal-organic nanocage, as shown by X-ray diffraction analysis. The new compound represents a scarce example of POM-encapsulated metal-organic nanocage. Additionally, its photocatalytic degradation of RhB was also investigated.

Zr-MOFs based on Keggin-type polyoxometalates for photocatalytic hydrogen production

The porous and water-stable polyoxometalates-based Zr-MOFs PW12@UiO-NH2 was proposed for photocatalytic H2 evolution and degradation pollutants via adopting Keggin-type polyoxometalates (POMs) into UiO-66-NH2 through a facile one-step solvothermal method. Systematically characterizations were carried out to confirm the encapsulation of Keggin-type PW12 within the cavities of porous UiO-66-NH2 without modifying its fundamental framework. Benifiting from the integration of Keggin-type PW12 units with redox activity and porous UiO-66-NH2, the results showed that enhanced photocatalytic H2 evolution performance and RhB degradation activity for PW12@UiO-NH2 were realized compared with pristine UiO-66-NH2 under visible-light irradiation. The significant improvement of photocurrent density under a monochromatic light irradiation implied the faciliated separation procedure of photo-generated charge carriers with the incorporation of Keggin-type PW12 units. Hence, our findings reveal a novel topology POM-based MOFs which paves a way for environmental and energy applications.

Preparation of α-Fe2O3 nanowires through electrospinning and their Ag3PO4 heterojunction composites with enhanced visible light photocatalytic activity

ABSTRACTIn this paper, α-Fe2O3 nanowires were prapared by electrospinning combined with calcination, and the effect of calcination temperature on their microstructure and properties were also analyzed. The results show that the α-Fe2O3 nanowires after calcined at 550°C present hollow-pipe-like structure and good photocatalytic degradation of RhB and water splitting to produce O2 evolution. Based the α-Fe2O3 nanowires, the α-Fe2O3/Ag3PO4 nanocomposites were fabricated using ion exchange method, and the water splitting results show that the formation of the heterojunction between α-Fe2O3 nanowires and Ag3PO4 particles can effectively promote electron-hole separation and then improve the photocatalytic activity.

Self-Assembled Mesoporous Carbon Nitride with Tunable Texture for Enhanced Visible-Light Photocatalytic Hydrogen Evolution

Mesoporous carbon nitride with novel morphology has been successfully fabricated by using ionic liquid and supramolecular precursor cyanuric acid-melamine complex as the template and precursor, respectively. The texture of carbon nitride is controlled by adjusting the ionic liquid concentration and type. The results find that a disordered hollow carbon nitride box morphology with pores in the wall can be obtained under lower IL1 concentration. With increasing of ionic liquid content, the texture turns to be a layered structure. The disordered nanosheets and hollow tube with large pores in the shell can be fabricated by using IL-2 and IL-3 as templates, respectively. Besides, as-prepared mesoporous carbon nitride samples display the excellent light harvesting properties and fast separation rate of photogenerated carrier. Moreover, mesoporous carbon nitride CN-0.1 exhibits a higher photocatalytic hydrogen evolution rate (120.3 μmol h–1) under visible light irradiation owing to the special structure and the presence of multiple mesopores, which is approximately 25.6, 1.7 times as high as that of bulk carbon nitride calcined by melamine and CN, respectively. Furthermore, photocatalytic RhB degradation rate is enhanced by using CN-0.1 compared with pure CN. This method provides more insights into designing novel visible light driven photocatalysts by using ionic liquids.

Ultrathin nanosheets of graphitic carbon nitride heterojunction with flower like Bi2O3 for photodegradation of organic pollutants

The flower like microrods (MR) of α-Bi2O3 defined as (MR-Bi2O3) and ultrathin g-C3N4(UT-C3N4) p-n junction was successfully prepared by loading different concentrations of UT-C3N4 over MR-Bi2O3. Their morphology and structure were thoroughly studied by XRD, SEM, XPS, TEM, UV–vis diffuse reflectance spectra, FT-IR and PL spectra. The results showed that the UT-C3N4 has been wrapped in the flower like MR-Bi2O3. The designing of the p-n junction of UT- C3N4 and MR-Bi2O3 can enhance the separation efficiency of the electron-hole pairs. The photocatalytic degradation of RhB was drastically increased by designing of the p-n junction that is due to the photogenerated electron–hole pair’s separation efficiency.

Influences of Graphene Nanosheets Coating on Selectively Exposed Crystal Facet ZnO

AbstractGraphene/ZnO composite attracting increasing attention due to great photoelectrochemical performance, however, graphene nanosheets tend to be coated on the one crystal plane of ZnO is rarely investigated. Herein, we synthesized different ZnO micro‐nanoparticles with selectively exposed crystal facet through a hydrothermal process by controlled some parameters such as temperature, concentration of reagents and reaction time, and the corresponding RGO/ZnO composites were obtained. Characterization by SEM and TEM, it was first time demonstrate that graphene nanosheets were tend to be coated on the (100) and (002) crystal facets of ZnO micro‐nanoparticles. We further discover that the largest exposed crystal facet of RGO/ZnO became (101) crystal plane. Regarding their performance in photocatalytic RhB degradation, exposed crystal facets of ZnO were found to impose crucial influence: the sample‘s photoelectrochemical properties are positively related to exposed degree of (101) facet, and it trend follows the order ZnO101 > RGO/ZnO101 > ZnO100 > RGO/ZnO100 > RGO/ZnO002 > ZnO002. Moreover, it can provide a new strategy that the films were coated on suitable crystal facet to change the photoelectrochemical properties of composite.

Novel C fibers@MoS2 nanoplates core-shell composite for efficient solar-driven photocatalytic degradation of Cr(VI) and RhB

As a green and efficient strategy for wastewater treatment, solar-driven photocatalysis has received great attention in recent years, in which graphene-like semiconductor MoS2 has been considered as a promising photocatalyst due to its strong absorption on visible light originating from its narrow band-gap. But the poor photocatalytic activity resulted from the strong recombination of photogenerated electron-hole pairs severely limits the practical application of MoS2 photocatalysts. In this work, we report a novel C fibers@MoS2 nanoplates core-shell composite prepared by a simple, one-step thermal evaporation method, in which numerous MoS2 thin nanoplates are in-situ, densely and even vertically grown on the surface of the C fibers. Such composite exhibits superior solar-driven photocatalytic activity and excellent stability for degrading environmental pollutants like inorganic Cr(VI) and organic rhodamine B. In comparison with the commercially available MoS2 powder, the as-prepared composite shows an increased reaction rate constant by a factor of approximately 7.0 for the photocatalytic reduction of Cr(VI) and about 2.6 for the photodegradation of rhodamine B under simulated sunlight irradiation. The enhanced performance of this composite could be attributed to the improved efficient separation of photogenerated electron-hole pairs and fast transfer of charge carriers caused by the highly conductive C fibers.

Photocatalytic, Fenton and photo-Fenton degradation of RhB over Z-scheme g-C3N4/LaFeO3 heterojunction photocatalysts

Z-scheme g-C3N4/LaFeO3 heterojunction photocatalysts were prepared by calcining the uniformly mixed g-C3N4 nanosheets and LaFeO3 nanoparticles at 300 °C for 1 h. The as-prepared g-C3N4/LaFeO3 composites were systematically characterized by XRD, SEM, TEM, XPS, UV–vis DRS, PL spectroscopy, EIS and photocurrent response. It is demonstrated that LaFeO3 nanoparticles (average size: ca. 35 nm) are uniformly assembled onto the surface of g-C3N4 nanosheets through chemical bonding, leading to the formation of g-C3N4/LaFeO3 heterojunctions. The photocatalytic, Fenton and photo-Fenton performances of the samples were investigated by degrading RhB using simulated sunlight as the light source. Compared to bare LaFeO3 and g-C3N4, the g-C3N4/LaFeO3 composites exhibit significantly enhanced photocatalytic and photo-Fenton degradation of the dye, and the maximum activity is observed for the 15%g-C3N4/LaFeO3 composite. Moreover, the photo-Fenton performance of the composites is much higher than the photocatalytic or Fenton performances. The much improved photo-fenton activity is ascribed to the efficient separation of photogenerated electron-hole pairs due to the Z-scheme electron transfer and the synergistic effect between LaFeO3 and g-C3N4. •OH radicals were examined by PL spectroscopy using TPA as a probe molecule, clearly revealing the •OH generation, and moreover, the •OH yield and the dye degradation rate show a similar variation between different cases of the catalysis process. This suggested that •OH is the dominant reactive species causing the dye degradation. The underlying photo-Fenton mechanism of the composites is discussed.

ZIF-67-derived Co3O4 micro/nano composite structures for efficient photocatalytic degradation

Flowerlike ZIF-67 micro/nano composite structures were developed by the evolution of ZIF-67 rhombododecahedrons ZIF-67(r) via facile ion-assistant solvothermal treatment. The morphology evolution of ZIF-67 with time-on-stream was studied. The flowerlike Co3O4 micro/nano composite were formed under calcination at relatively low temperature. The flowerlike Co3O4 micro/nano composite structures showed good catalytic properties for photocatalytic degradation of RhB (83.2%), higher than that of Co3O4(p) (69.7%) and Co3O4(r) (75.7%) after 90 min irradiation.

In situ synthesis of sulfur doped carbon nitride with enhanced photocatalytic performance using DBD plasma treatment under H2S atmosphere

Dielectric barrier discharge (DBD) plasma is considered to be a promising method to synthesize and modify solid catalyst. In this work, DBD plasma was used to synthesize S-doped g-C3N4 catalyst in situ under H2S atmosphere for the first time. XRD, N2 adsorption, UV-Vis, SEM, XPS, EIS, and PL were used to characterize the obtained catalysts. The photocatalytic RhB degradation of as-prepared catalyst was investigated. The results show that, compared with traditional roasting method, H2S plasma treatment can dope more sulfur into g-C3N4 lattice. Such high sulfur content has a significant impact on the morphology, optical property, and electronic structure of the catalyst. The sulfur doped g-C3N4 prepared by plasma treatment displays much higher RhB degradation rate than that prepared by traditional roasting method. This work provides a new strategy for synthesizing heteroatoms doped g-C3N4 based catalyst.