Decomposition Of RhB Research Articles

MnO2 decorated silicon nanowires: A novel photocatalyst for improved Rhodamine B removal under visible light exposure

Pollution triggered by organic dyes is a prominent global concern. Thus, it is imperative to devise an effective preventative strategy to tackle this matter. Herein, using the chemical electroless deposition process, a novel SiNWs/MnO2 photocatalyst was successfully manufactured for efficacious photocatalytic purification under visible lighting. Through a series of characterization techniques, the structural, morphological, compositional, and optical features of MnO2-deposited silicon nanowires were thoroughly investigated. The photocatalytic ability of the resultant sample was reckoned by degrading Rhodamine B upon visible exposure. Following 180 min of brightness, the findings found that SiNWs/MnO2 displayed remarkable effectiveness, with a lessening of 93.4 %. The findings demonstrated a significant enhancement in degradation performance linked to the rising surface area and enhanced electron-hole segregation efficiency provided by silicon nanowires. Also, the sample's recyclability was assessed, exhibiting an encouraging sustainability with a slight fall in effectiveness (∼10%) after 6 straight utilizes. Furthermore, scavenging tests have shown that •OH and •O2− were prevalent species accountable for the RhB degradation reaction. Eventually, founded on the results, a plausible mechanism for RhB decomposition was suggested. Altogether, given the straightforward manufacturing method and impressive performance, the study argues that the novel SiNWs/MnO2 might be an intriguing photocatalyst for water contaminant remediation.

PH-Dependent photocatalytic performance of faceted BiOBr semiconductor particles in degradation of dyes

Bismuth oxyhalides, such as bismuth-oxy-bromide (BiOBr), show high performance in photocatalytic oxidation of water pollutants. Process conditions, and in particular the pH of the solution, largely affect the photocatalytic efficacy, which is fundamentally poorly understood. We prepared {001} faceted bismuth-oxy-bromide (BiOBr), and determined by advanced AFM analysis that the surface charge of the {001} facet of BiOBr is slightly positive at acidic pH (pH 3) and significantly negative and increasing in negative surface charge in the order pH 6 < pH 9. Decomposition of MB or RhB by illumination of BiOBr is strongly favored by basic conditions (pH 9-10), as evident from discoloration experiments, and determination of the TOC as a function of time of illumination. Reference experiments show the pH dependent degradation profiles cannot be explained by differences in quantities of adsorption of the dye, but rather by the lifetime and/or quantity of BiOBr related photoexcited (surface) charge carriers (holes and electrons) – correlating with surface charge. Using MeOH and other scavengers, we show oxidation of MB or RhB is mainly induced by superoxide anions (•O2− radicals) at low pH and by holes or hydroxyl radicals at high pH – in agreement with surface charge induced band bending. This study provides novel understanding of the pH dependence of the rates of photocatalytic degradation of dyes using BiOBr photocatalysts.

Facile synthesis of Co, Fe-bimetallic MIL-88A/microcrystalline cellulose composites for efficient adsorptive and photo-Fenton degradation of RhB dye

Photo-Fenton technology is effective in treatment of dye containing effluents in water under visible light illumination. The present article reports fabrication of a considerably efficient photo-Fenton catalytic system, the Co, Fe-MIL88/MCC composite, by a mild hydrothermal method. The composite containing bimetals Co2+/Co3+ and Fe2+/Fe3+ ions with coordination environments used as activators of H2O2-assited visible light photo-Fenton degradation of RhB. The effects of initial pH, catalyst dosage and H2O2 concentration on RhB decomposition were explored. Nearly 87% of RhB molecule was removed within 100 min in the Co, Fe-MIL88/MCC/H2O2/Visible system ana maintain the recyclability rate of more than 82.2% after five successive cycles. The photoinduced •O2− and •OH plays a major role in efficient removal of RhB. The excellent catalytic performance of the composite can be credited to the proficient electrons transfer by Fe2+/Fe3+ and Co2+/Co3+ redox cycles, activation of H2O2 by photoexcited electrons to generate •OH. As well, the optimal Co, Fe-MIL88 (Co/Fe in ratio 1/2 wt%)/MCC composite exhibited good recyclability and stability.

The synergetic effect of light and ultrasonic vibration to improve the photocatalysis activity of BiOCOOH nanostructures

The wide band gap and high recombination of photoinduced electron-hole decreases the photocatalytic activity of BiOCOOH. In this work, remarkable piezocatalytic decomposition of RhB by BiOCOOH nanostructure has been discovered. Coupling with piezocatalysis, the photocatalytic degradation capacity under visible light and UV light could be enhanced. BiOCOOH nanotube showed higher piezo-photocatalytic activity than BiOCOOH microspheres. BiOCOOH nanotube decomposes 99% RhB under coexcitation of UV light and ultrasonic vibration in 30 min, which is higher than single piezocatalysis (67.8%) and photocatalysis (77.5%). The distinct piezocatalytic and piezo-photocatalytic activity are attributed to the enhanced electron-hole separation by the piezopotential induced under ultrasonic vibration.

Nano TiO2 and Molybdenum/Tungsten Iodide Octahedral Clusters: Synergism in UV/Visible-Light Driven Degradation of Organic Pollutants.

Emissions of various organic pollutants in the environment becomes a more and more acute problem in the modern world as they can lead to an ecological disaster in foreseeable future. The current situation forces scientists to develop numerous methods for the treatment of polluted water. Among these methods, advanced photocatalytic oxidation is a promising approach for removing organic pollutants from wastewater. In this work, one of the most common photocatalysts-titanium dioxide-was obtained by direct aqueous hydrolysis of titanium (IV) isopropoxide and impregnated with aqueous solutions of octahedral cluster complexes [{M6I8}(DMSO)6](NO3)4 (M = Mo, W) to overcome visible light absorption issues and increase overall photocatalytic activity. XRPD analysis showed that the titania is formed as anatase-brookite mixed-phase nanoparticles and cluster impregnation does not affect the morphology of the particles. Complex deposition resulted in the expansion of the absorption up to ~500 nm and in the appearance of an additional cluster-related band gap value of 1.8 eV. Both types of materials showed high activity in the photocatalytic decomposition of RhB under UV- and sunlight irradiation with effective rate constants 4-5 times higher than those of pure TiO2. The stability of the catalysts is preserved for up to 5 cycles of photodegradation. Scavengers' experiments revealed high impact of all of the active species in photocatalytic process indicating the formation of an S-scheme heterojunction photocatalyst.

Effect of brookite on the photocatalytic properties of mixed-phase TiO2 obtained at a higher temperature

The paper presents the synthesis and properties of nanometric TiO2 powders obtained by the sol–gel method at elevated temperatures. The presence of brookite inhibits the anatase - rutile transformation at higher temperatures. Even after the treatment of gel at 700 °C, a large amount of anatase in the TiO2 powders was found. Measurements in the UV–vis range were performed to determine the optical band-gap of TiO2. Results of photocatalytic tests for the degradation of RhB and NO under UV are also presented. The decomposition efficiency of the powders was compared with the P25 before and after treatment at 700 °C. The obtained powders despite being prepared at this temperature were more efficient in both RhB and NO decomposition compared to the reference sample. The results indicate the possibility of modifying materials that are produced or work at high temperatures, by adding such TiO2 with high photocatalytic capacity in the UV range.

Direct Z-Scheme AgBr/β-MnO2 Photocatalysts for Highly Efficient Photocatalytic and Anticancer Activity.

The preparation of visible light-responsive efficient photocatalysts for removing organic contaminants from water and killing cancer cells has gotten a lot of attention due to the growing global concern. In this study, we have successfully fabricated an efficient AgBr/β-MnO2 nanocomposite via a facile deposition and precipitation method at room temperature. Techniques such as XRD, SEM-EDS, TEM, DRS, PL, EIS, ESR, and FTIR were used to determine the crystalline, structural, morphological, optical, and other properties. The SEM and TEM analyses reveal that AgBr NPs are decorated on the surface of β-MnO2, which possesses rods with a sphere-like structure for AgBr/β-MnO2. The EDX analysis confirms the existence of Mn, O, Ag, and Br elements in the nanocomposites without an extra peak, indicating that the synthesized samples are highly pure. The high photocatalytic performance of AgBr/β-MnO2 could be attributed to the formation of Ag NPs and the construction of the Z-scheme heterojunction between AgBr and β-MnO2. This may enhance fast light absorption and efficient photogenerated (e–/h+) pairs, as indicated by EIS and photoluminescence measurements, which in turn achieved high activity for the decomposition of MB (97%, in 12 min), RhB (98.9%, in 9 min), and paracetamol (80%, in 180 min), respectively. The kinetic model study proposed that the first-order model showed a better fit than the zero- and second-order for the photocatalytic decolorization of RhB dye. XRD analysis of 0.2 AgBr/β-MnO2 before and after recycling confirms the high stability of the catalyst. HPLC results showed that no detectable by-products are produced through the decomposition of paracetamol. Interestingly, 0.2 AgBr/β-MnO2 nanocomposites showed visible light-induced anticancer activity against A549 cancer cell lines. The mechanistic degradation pathway has been proposed using the involvement of active species like superoxide radicals (−•O2) and photoinduced holes (h+). The proposed work focuses on synthesizing effective photocatalysts in a less hazardous environment with superior biological activity.

Tuning the particle size, physical properties, and photocatalytic activity of Ag3PO4 materials by changing the Ag+/ ratio

This study demonstrates the influence of the Ag+/ ratio in precursor solution on the crystal structural formation, morphology, physical properties, and photocatalytic performance of a Ag3PO4 photocatalyst that is fabricated, using a facile precipitation method, from AgNO3 and Na2HPO4⋅12H2O. The material characterizations were carried out using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area, Fourier transform infrared (FTIR) absorption, Raman scattering, x-ray photoelectron spectroscopy (XPS), UV-vis absorption, and photoluminescence (PL). The results show that Ag3PO4 crystallizes better when the excess content increases, and the lattice parameters decrease slightly, while the crystal diameter and the particle size increase. This change is also observed in the Raman scattering and FTIR spectra with the increase in the vibration frequency of the [PO4] group. The compression of the [PO4] unit was also confirmed in the XPS spectra with the shift of P 2p peaks toward higher binding energy. The photocatalytic results showed that the samples synthesized from excess solution exhibited higher photocatalytic performance compared to the sample with a Ag+/ ratio of 3:1. A sample prepared from the precursor solution with a Ag+/ ratio of 3:1.5 was optimal for RhB decomposition under both visible light and natural sunlight, completely decomposing 10 ppm RhB after 15 minutes of xenon lamp irradiation and after 60 minutes under solar light irradiation. This is attributed to the high crystallinity, small particle size and low electron–hole recombination rate of the sample.

Facile synthesis of CdO-ZnO heterojunction photocatalyst for rapid removal of organic contaminants from water using visible light

The synthesis of an efficient photocatalyst for removing organic contaminants in the water is of major importance for researchers working in heterogeneous photocatalysis. To do this, we provide the co-precipitation approach for synthesizing heterojunction nanocomposite (CdO-ZnO). Standard analytical techniques were used to characterize the synthesized components. According to the XRD and DRS results, a composite of ZnO and CdO was effectively synthesized with a shift of λmax towards the higher wavelength. SEM pictures reveal well-decorated oval-shaped CdO nanoparticles with hexagonal ZnO particle morphology. Under visible light irradiation, the as-prepared CdO-ZnO nanocomposite demonstrated very efficient photocatalytic performance as measured by the decomposition of RhB, MB, paracetamol, and ciprofloxacin in an aqueous solution. The photo-mineralization of MB and RhB over the most active CZ-3 catalyst was also assessed by measuring the decrease in TOC (total organic carbon) content over time when exposed to visible light. The breakdown of paracetamol produces no hazardous by-products, according to high-performance liquid chromatography (HPLC) study. The photocatalytic process appears to be dominated by OH and h+, according to the radical scavenger tests.

Construction of pyroelectrically-driven BiFeO3@CuBi2O4 nanofiber composite catalyst for enhanced pyrocatalytic activities under room-temperature cold and hot cycles

In this present work, a significant enhancement of pyroelectrically-driven catalytic activity is found in BiFeO3@CuBi2O4(BFO@CBO) heterostructures synthesized by electrospinning and then calcining. BFO can decompose up to 74.1% RhB dye in aqueous solution (5 mg/L) at cold and hot cycles of 15 °C to 45 °C. With the increase of CBO composite content from 0wt% to 10wt% in BFO nanofibers, the RhB decomposition rate of BFO@CBO heterostructure increased first and then decreased, reaching the maximum of 95% at 5wt%. The BFO@5%CBO composite with the best pyroelectrically catalytic activity had the highest bactericidal rate, and its bactericidal effect on Salmonella and Staphylococcus aureus was 96.2% and 96.8%, respectively. The increased catalytic activity of BFO@CBO may be due to the formation of heterojunctions, in which the electric field effectively separates the pyrolytic induced electron-hole under cold and hot cycles conditions. The BFO@CBO pyroelectric catalyst may have the potential to decompose dye wastewater and sterilize bacteria by collecting alternating heat energy.

ENHANCE A PHOTOCATALYTIC ACTIVITY ON Ag3PO4 BY Ag\Ag3PO4 COMPOSITES

In this study, we investigated the formation and influence of Ag particles on the physical properties and photocatalytic performance of Ag3PO4 photocatalysts when Ag particles adhered to the Ag3PO4 surface. The material is prepared by a simple precipitation method with illumination. The properties of the materials were investigated by X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM), UV-vis absorption, and the photocatalytic ability to decompose organic solutions. The results show the vibrational change of the [PO4] group in the structure presented in the Raman scattering spectrum highest RhB decomposition. The experimental results indicated that the Ag\Ag3PO4 showed highly efficient and stable photocatalytic activity under visible light irradiation. The Ag\Ag3PO4 sample with the Ag+\PO43- the ratio of 3.6\1 gave efficiency when stimulated with visible light of Xenon lamps. This sample degraded almost completely to RhB in 10 ppm solution after 15 min of illumination, with a decomposition rate of 0.241 min-1.

Piezoelectric BaTiO3 with the milling treatment for highly efficient piezocatalysis under vibration

The hydrothermally-synthesized barium titanate (BaTiO3) nanofibers are mechanically milled and used to for the piezocatalytic RhB dye decomposition. It is found that the mechanical milling can improve the piezocatalytic performance of BaTiO3 nanofibers. With the increasing of the milling time from 0 to 120 min, the RhB dye decomposition ratio of BaTiO3 nanofibers first increases and then decreases. When the milling time is 30 min, for the 20 min vibration time, the RhB decomposition ratio of BaTiO3 is 94%, which is much higher than that (~65%) of the unmilled BaTiO3. On one hand, the enhancement in piezocatalysis of BaTiO3 may be originated from the exposure of active sites due to the increasement of the specific surface area after the mechanical milling. On the other hand, it is also found that the ferroelectric polarization strength of BaTiO3 nanofibers obviously increases after the mechanical milling, which is helpful to reduce the recombination of these positive and negative carriers in the catalytic process, resulting in the enhanced piezocatalysis performance. The mechanical milling provides a convenient, fast, and effective method for improving the piezocatalytic activity of BaTiO3 nanofibers.

Floating Carbon-Doped TiO2 Photocatalyst with Metallic Underlayers Investigation for Polluted Water Treatment under Visible-Light Irradiation

In the current study, we analysed the influence of metallic underlayers on carbon-doped TiO2 films for RhB decomposition and Salmonella typhimurium inactivation under visible-light irradiation. All the experiments were divided into two parts. First, layered M/C-doped-TiO2 film structures (M = Ni, Nb, Cu) were prepared by magnetron sputtering technique on borosilicate glass substrates in the two-step deposition process. The influence of metal underlayer on the formation of the carbon-doped TiO2 films was characterised by X-ray diffractometer, scanning electron microscope, and atomic force microscope. The comparison between the visible-light assisted photocatalytic activity of M/C-doped TiO2 structures was performed by the photocatalytic bleaching tests of Rhodamine B dye aqueous solution. The best photocatalytic performance was observed for Ni/C-doped-TiO2 film combination. During the second part of the study, the Ni/C-doped-TiO2 film combination was deposited on high-density polyethylene beads which were selected as a floating substrate. The morphology and surface chemical analyses of the floating photocatalyst were performed. The viability and membrane permeability of Salmonella typhimurium were tested in cycling experiments under UV-B and visible-light irradiation. Three consecutive photocatalytic treatments of fresh bacteria suspensions with the same set of floating photocatalyst showed promising results, as after the third 1 h-long treatment bacteria viability was still reduced by 90% and 50% for UV-B and visible-light irradiation, respectively. The membrane permeability and ethidium fluorescence results suggest that Ni underlayer might have direct and indirect effect on the bacteria inactivation process. Additionally, relatively low loss of the photocatalyst efficiency suggests that floating C-doped TiO2 photocatalyst with the Ni underlayer might be seen as the possible solution for the used photocatalyst recovery issue.

In-situ synthesis of a novel ZnO/CuCo2S4 p-n heterojunction photocatalyst with improved phenol and rhodamine B degradation performance and investigating the mechanism of charge carrier separation

Designing high-performance ZnO-based photocatalysts can be a promising solution to environmental problems. However, pure ZnO with a large band gap has challenges such as excitation under UV light and high recombination of charge carriers. Construction of heterojunction with a narrow band gap semiconductor can be used as a suitable approach to increase the photocatalytic efficiency of ZnO. Considering that, in the present study, a novel ZnO/CuCo2S4 n-n heterojunction nanocomposite was successfully synthesized by the in-situ hydrothermal method. The purity of the prepared photocatalysts was confirmed by XRD, FT-IR, EDX, and XPS analyzes. FESEM, TEM, and HRTEM images disclosed the morphology of CuCo2S4 nanoparticles on spindle-like ZnO. The ZnO/CuCo2S4 photocatalyst showed 14 (63) and 4.6 (17) times higher photocatalytic performance than ZnO and CuCo2S4 for photodegradation of phenol (RhB) under visible light, respectively. The photocatalytic decomposition of phenol and RhB over ZnO/CuCo2S4 followed a pseudo-first-order kinetic with the rate constants of 109 × 10−4 and 485 × 10−4 min−1, respectively. The significantly enhanced photocatalytic activity of ZnO/CuCo2S4 nanocomposite can be attributed to the heterojunction formation, which provides more reaction active sites, excites semiconductors in the visible region, and increases the separation and transport of charge carriers. The narrow band gap of CuCo2S4 that led to the absorption of light by the nanocomposite in the higher wavelength range was also investigated by UV–vis DRS and Tauc plots. Suppressing the recombination of electron-hole pairs in the prepared nanocomposite relative to the components was shown by PL spectroscopy. Photocurrent and EIS data were also obtained, and based on them, the possible mechanism of photocatalytic degradation was proposed.

Development of photocatalyst based on NaYF4: Yb, Tm@NaYF4: Yb, Ce/NH2-MIL-101 (Cr): Doping Ce3+ ions to promote the efficient energy transfer between core and shell

Utilization of the whole solar spectrum for the photocatalysis is still a challenge and interesting topic. A series of novel photocatalysts are fabricated by combination of core–shell upconversion nanoparticles NaYF4: Yb, Tm@NaYF4: Yb, Ce (Tm@Ce) with the NH2-MIL-101 (Cr) (NMC) (Tm@Ce/NMC). Tm@Ce/NMC displays the high stability, wide photoresponsive range from UV–Vis to NIR, and excellent photocatalytic activity for decomposition of RhB. With the optimal doping amount of Ce3+ ions and ratio between Tm@Ce and NMC, the degradation of RhB is improved by 1.13, 1.14, and 1.50 times as compared with NaYF4: Yb, Tm/NMC (Tm@NMC), under the simulated solar light, UV + Vis, and NIR, respectively. The enhanced photocatalytic activity of Tm@Ce/NMC is mainly attributed to the efficient energy transfer between core and shell by the doping Ce3+ ions along with the distinct charge separation and suppressed recombination. By the controlled synthesis, the NaYF4: Yb, Tm (YT) nanoparticle is developed with the similar size as the Tm@Ce to further testify the effect of doping Ce3+ ions and exclude the influence of the increased size. The photocatalytic activity of YT/NMC is the less than that of Tm@Ce/NMC, which is almost the same with that of Tm/NMC. It suggests that to merely increase the size of upconversion nanoparticles is not the judicious choice for enhancement of the photocatalytic activity. On the basis of the trapping experiments and other spectra properties, the possible photocatalytic mechanism is conjectured, which is helpful to refine the structure design with the ultimate aim to get the robust photocatalyst.

Room-temperature synthesis of γ-Ga2O3 nanoparticles from gallium metal via ultrasound irradiation

In this study, gallium oxide (Ga2O3) nanoparticles were synthesized by sonochemical techniques at room temperature. We investigate the ultrasound irradiation conditions and the solvent type to synthesize Ga2O3 nanoparticles. γ-Ga2O3 nanoparticles were synthesized by irradiating gallium metal with ultrasound in hydrazine monohydrate solvent. The irradiation of hydrazine with ultasound suppresses the generation of ·OH, and GaOOH was not formed, and gallium metal directly oxidized. When the synthesized γ-Ga2O3 nanoparticles were heat-treated, a transition to β-Ga2O3 was observed. The heat-treated Ga2O3 nanoparticles showed excellent photocatalytic activity for the decomposition of RhB under UV irradiation.

Synergistic catalysis of Fe3O4/CuO bimetallic catalyst derived from Prussian blue analogues for the efficient decomposition of various organic pollutants

• Fe 3 O 4 /CuO nanoparticles were synthesized via a facile in-situ method by using CuFe-PBA as precursor, synthesized via self-assembly method. • Fe 3 O 4 /CuO/PS/Vis-light based system can efficiently degrade Congo Red, Rhodamine-B and Methyl orange dyes in 10 mins, 20 mins and 18 mins, respectively, for a broader pH range. • Mechanism of synergistic catalysis of Fe 3 O 4 /CuO catalyst was deep-rooted for its robust photocatalytic performance. • Fe 3 O 4 /CuO has excellent stability and reusability and is an eco-friendly safe and cost effective approach for degradation of various organic-pollutants. In-situ synthesis of CuO/Fe 3 O 4 nano-composite from Cu-Fe based Prussian Blue Analogues (PBA) by using as a precursor is reported. CuO/Fe 3 O 4 catalyst was practiced as a heterogeneous catalyst, by activating persulfate (PS), for the photo-decomposition of different azo dyes (RhB, MO, CR) under visible light. CuO/Fe 3 O 4 catalyst has validated its excellent photocatalytic removal of all three organic dyes. Synergistic linkage of Fe 3 O 4 with CuO has enhanced the light absorption of CuO/Fe 3 O 4 catalyst resulting in excellent photocatalytic removal of all pollutants under various pH systems amongst which neutral pH was found the efficient one. ESR and radicals capturing studies revealed that SO 4 •− and HO • radicals are dominant ones. The mechanism and the reaction pathway for the decomposition of RhB were also identified. Excellent recycling and stability of as-prepared bimetallic catalyst make it highly favorable, as its application for the removal of organic pollutants to address health remediation and environmental toxicology.

RETRACTED: The synthesis of Bi12GeO20/Ag3PO4 nanowire composite for increased photocatalytic activity and decreased electron/hole recombination

Abstract Bi12GeO20 nanowires uniformly decorated with ultrafine Ag3PO4 nanoparticles (Bi12GeO20/Ag3PO4) were synthesized. The Bi12GeO20/Ag3PO4 nanowire composite with 10 wt% of Ag3PO4 exhibited significantly improved photocatalytic performance and excellent stability over pure Bi12GeO20, Ag3PO4 and other composites, with the RhB dye decomposition efficiency reaching 94.2%. The electrochemical and photocurrent response measurements suggested that the electrons generated in Bi12GeO20 during the photocatalytic reaction could be quickly transferred to the Ag3PO4 surface, resulting in increased electron/hole separation. The trapping experiments with different scavengers and ESR results revealed that holes and ·O2− were the dominant active species for the photocatalytic decomposition of RhB, and the presence of Ag3PO4 was beneficial to generate more ·O2− species and enlarge the active surface area, leading to significantly improved photocatalytic performance. The presented photocatalyst heterostructure composed of appropriate semiconductor nanoparticles and one-dimensional nanowires in this study could be extended to the construction of other photocatalysts for a wide variety of photocatalytic applications.

TiO2-coated copper zinc tin sulfide photocatalyst for efficient photocatalytic decolourization of dye-containing wastewater

A hierarchical composite of TiO2 coated on Cu2ZnSnS4 (CZTS/TiO2) with various molar ratios was synthesized by hydrothermal process combined with subsequent grinding and low-temperature calcination. The optimal molar ratio of CZTS to TiO2 in CZTS/TiO2 composites is 1:1. Due to the staggered band structure of CZTS and TiO2, the designed CZTS/TiO2 superstructure extends the light absorption of TiO2 into visible region and even separates photoinduced carriers well so that it presented higher photocatalytic activity than pristine CZTS and anatase TiO2. The photodegradation efficiency (PE) of aqueous RhB solution (10 mg/L) reached 95.04% with 120 min. Furthermore, the photodegradation reaction obeyed the first-order kinetics, which the apparent rate constant (kapp) was 4.87 and 2.70 times higher than that of pure CZTS and TiO2, respectively. More importantly, the synthesized CZTS/TiO2 composites exhibited excellent durability and recyclability in the photocatalytic process. Even after using for four times, the photocatalytic activity was hardly any decay. The PE decreased significantly with increasing pH of dye solutions. At pH of 2–6, at least 85% of the dye solution was degraded. Studying critical role of h+ and •O2− radicals involved in RhB decomposition. The results indicates that CZTS/TiO2 photocatalyst could act as a perspective candidate in wastewater purification applications.

Constructing novel hierarchical porous hydrangea-like ZnWO4 microspheres with enhanced photocatalytic performance

Hierarchical porous hydrangea-like ZnWO4 microspheres were synthesized via a facile and simple ethylene glycol (EG) assisted-solvothermal route, in which EG acted as solvent and structure-directing agent. XRD, FTIR, Raman, SEM, TEM, DRS and N2 absorption-desorption have been used to obtain the purity and morphological information as well as BET surface area of the samples. SEM and TEM results demonstrated that the hierarchical porous hydrangea-like ZnWO4 microspheres consisted of many intercrossing curved nanoflakes. The hierarchical porous ZnWO4 microspheres exhibit a high specific surface area up to 92.03 m2/g. The morphological evolution results revealed that the reaction time was crucial to guide the self-assembled process from smaller building units (nanoflakes) to larger 3D flowerlike ZnWO4 hierarchical porous microspheres. Furthermore, this unique hierarchical porous material was effective in the decomposition of RhB in aqueous solution under UV light irradiation, which might be ascribed to the synergistic effect of hierarchical porous structures, large surface areas and good crystallinity of the products.