Photocatalytic Degradation Efficiency Research Articles

Copper Doping of CdS Nanoflakes and Nanoflowers for Efficient Photocatalytic Degradation of MB and MV Dyes

Copper Doping of CdS Nanoflakes and Nanoflowers for Efficient Photocatalytic Degradation of MB and MV Dyes

Efficiency and Mechanistic Insights of Photocatalytic Decomposition of Tetracycline and Rhodamine B utilizing Z-scheme g-C3N4/SnWO4 Heterostructures under Visible Light Irradiation

The hydrothermal approach was used in the design and construction of the SnWO4 (SW) nanoplates anchored g-C3N4 (gCN) nanosheet heterostructures. Morphology, optical characteristics, and phase identification were investigated. The heterostructure architect construction and successful interface interaction were validated by the physicochemical characteristics. The test materials were used as a photocatalyst in the presence of visible light to break down the antibiotic tetracycline (TC) and the organic Rhodamine B (RhB). The best photocatalytic degradation efficiency of TC (97%) and RhB (98%) pollutants was demonstrated by the optimized 15 mg of gCNSW-7.5 in 72 and 48 minutes, respectively, at higher rate constants of 0.0409 and 0.0772 min–1. The interface contact between gCN and SW, which successfully enhanced charge transfer and restricted recombination rate in the photocatalyst, is responsible for the enhanced performance of the gCNSW heterostructure photocatalyst. In addition, the gCNSW heterostructure photocatalyst demonstrated exceptional stability and reusability over the course of four successive testing cycles, highlighting its durable and dependable function. Superoxide radicals and holes were shown to be key players in the degradation of contaminants through scavenger studies. The charge transfer mechanism in the heterostructure is identified as Z-scheme mode with the help of UV-vis DRS analysis. Attributed to its unique structural features, and effective separation of charge carriers, the Z-scheme gCNSW-7.5 heterostructure photocatalyst exhibits significant promise as an exceptionally efficient catalyst for the degradation of pollutants. This positions it as a prospective material with considerable potential across various environmental applications.

Green synthesis and studies on citrus medica leaf extract-mediated Au–ZnO nanocomposites: A sustainable approach for efficient photocatalytic degradation of rhodamine B dye in aqueous media

Abstract Incorporating narrow band gap oxide semiconductors and metals into zinc oxide (ZnO) nanostructures broadens the range of light sensitivity to include visible wavelengths. In this study, the photocatalytic degradation of rhodamine B (RhB) dye was studied as a model for environmental pollution in aqueous media. This study describes the use of photodegradation catalysts, including gold (Au), ZnO, and Au–ZnO nanocomposites (prepared in ratios of 90:10 and 95:5) using the extract of Citrus medica leaves. X-ray diffraction (XRD) findings have shown that ZnO nanoparticles (NPs) have a hexagonal wurtzite structure. Field emission-scanning electron microscopy findings have depicted that ZnO NPs have diverse shapes, including spherical, quasi-spherical, hexagonal, and anisotropic, with some clumping. Au exhibits consistent spherical shapes and sizes with even distribution. Au–ZnO (90:10) shows quasi-spherical NPs with interconnected spherical Au, forming a porous and uneven surface. Au–ZnO (95:5) has spherical gold nanoparticles (Au NPs) dispersed on a textured ZnO surface, with some clustering and size variation as evident from the transmission electron microscopy, atomic force microscopy, and diffuse reflectance UV-visible spectroscopy analysis. The characterization results have demonstrated the uniform distribution of Au across the ZnO lattice. Additionally, the XRD patterns confirmed the hexagonal wurtzite structure of ZnO. Furthermore, energy-dispersive analysis of X-ray (EDX)-mapping verified the inclusion of zinc, oxygen, and Au in the hybrid Au–ZnO nanocomposites and their effective distribution. The topological analysis revealed a rough surface for the generated nanostructures. By comparing the results of various techniques, EDX analysis using atomic and weight ratios confirmed the presence of oxygen and Au in the nanocomposite. Additionally, the surface area analysis (BET) test has reported that the adsorption and desorption of nitrogen follow a Type III isotherm. The presence of an H3-type hysteresis loop further confirms the mesoporous nature of the composites, which reports the presence of wedge-shaped pores. The Au–ZnO (90:10) nanocomposite exhibits a higher surface roughness compared to other composites. In addition, this UV-visible diffuse reflectance spectroscopy has enumerated the band gaps of various nanomaterials using UV-visible spectroscopy. Moreover, the analysis has unveiled that combining ZnO with Au NPs (doping) improved the photocatalytic performance of ZnO. This improvement is attributed to the formation of additional energy levels within the ZnO band gap due to the presence of Au ions. Experimental investigation of the breakdown of RhB dye under visible light irradiation revealed superior photocatalytic activity for the Au–ZnO (90:10) nanocomposite compared to both Au–ZnO (95:5) and pure ZnO and Au counterparts. Multiple experiments confirmed the effective photodegradation and removal of RhB dye from the aqueous medium using the nanocatalyst under visible light irradiation. Under optimal conditions (1.0 g·L−1 photocatalyst, 10 ppm RhB, and pH 10), 99% photodegradation efficiency was reached within 50 min of irradiation. Investigation of reactive species revealed that the increased effectiveness of photodegradation in Au–ZnO (90:10) stems from the presence of photogenerated holes and hydroxyl radicals. The study also analyzed the reaction kinetics and order, and the reusability of the best photocatalyst Au–ZnO (90:10)) was confirmed through five consecutive cycles, demonstrating its sustained effectiveness in photodegradation. These findings highlight the potential of Au–ZnO (90:10) nanocomposite as a promising material for photocatalytic degradation of organic dyes.

Enhanced photocatalytic degradation of diazinon using Ni:ZnO/Fe3O4 nanocomposite under solar light

BackgroundThe increasing photocatalytic activity of Ni:ZnO/Fe3O4 nanocomposite in the diazinon degradation under solar light compared to bare ZnO and Ni:ZnO nanoparticles was examined. MethodsThe synthesized nanoparticles and nanocomposite were characterized by SEM, MAP-EDX, XRD, FTIR, DLS, Zeta Potential and UV–Vis Spectrophotometer methods. The photocatalytic degradation of diazinon was investigated under sunlight illumination while continuously mixing on a stirrer for 180 min. Significant findingsThe highest degradation efficiency was achieved for 1.5 wt% Ni:ZnO nanoparticles and 1.0 wt% Ni:ZnO/Fe3O4 nanocomposite at a diazinon concentration of 10 mg/L for the nanoparticle dose equal to 2 g/L was 95 % and 93 %, respectively. The recycling photocatalysts were investigated. Application of H2O2, potassium peroxymonosulfate (PMS) and S2O82− as chemical oxidants increased the photocatalytic activity of the nanocomposite. The use of 1.0 wt% Ni:ZnO/Fe3O4 nanocomposite along with 0.01 M H2O2 displayed the increasing photocatalytic performance. The simultaneous photocatalytic degradation efficiency of combined H2O2 and 1.0 wt% NZF nanocomposite for 100 mg/l of diazinon increased from 44 to 82 %. The photocatalytic mechanism of diazinon was proposed in three pathways.

Advanced cellulose-based hydrogel TiO2 catalyst composites for efficient photocatalytic degradation of organic dye methylene blue

Sustainable cellulose-based hydrogels are used in medicine and environmental science. Hydrogels’ porosity makes them excellent adsorbents and stable substrates for immobilizing photocatalysts to remove organic dyes. Despite their potential, the implementation of hydrogels for this purpose is still limited due to their high synthesis temperature and low cellulose content. To overcome these challenges, this study develops cellulose-based hydrogels, which have a high cellulose content and can be easily synthesized under ambient conditions. Containing a higher cellulose concentration than previous hydrogels, the synthesized hydrogels are more stable and can be reused numerous times in treatment operations. The hydrogel properties were investigated using Fourier transform infrared spectroscopy, X-ray diffraction and thermal analysis. Scanning electronic microscopy revealed that TiO2 nanoparticles were homogeneously distributed throughout the hydrogel's matrices. In addition, transparent hydrogels allow light to pass through, making them suitable substrates to remove organic dye. The results showed that the hydrogel with TiO2 was able to degrade nearly 90% of organic dye within 180 min. Furthermore, the hydrogel with the embedded catalyst exhibits the potential for reusability with a regeneration efficiency of 80.01% after five runs. These findings suggest that this novel hydrogel is a promising candidate for water pollution remediation.

Photocatalytic dye degradation, H2 evolution, electrical and mechanical performances of mechano-synthesized multifunctional Bi2Te3 nanoparticles: Effect of milling time and thermal treatment

Bi2Te3 nanoparticles are synthesized by mechanical alloying the Bi and Te powders under the Ar and pressed powdered samples are sintered at 573 K. Rietveld refined XRD patterns, FESEM images and EDX spectra reveal the microstructure, morphology and phase purity of the samples. Bandgaps are obtained from the FTIR spectra and a blue shift with size reduction indicates the size confinement effect. The non Debye type ac conductivity and dielectric constant variations with milling time and sintering are measured. The improved photocatalytic degradation efficiency of the sintered sample (83.59 %) using Rhodamine B dye under visible light elucidates reduced porosity effect. The photocatalytic hydrogen evolution efficiencies of these nanoparticles are measured and a probable mechanism is depicted. The highest H2 generation efficiency (1462.5 μmol g−1h−1) is observed with the sintered sample. Microhardness measurement reveals normal indentation size effect. Empirical correlations among electrical conductivity, microhardness and photodegradation are established for the first time.

Construction of Z‐scheme 1T/2H‐MoS2/CdS for improving photocatalytic degradation of antibiotic residues

Abstract1T/2H‐MoS2/CdS composite was effectively prepared by a two‐step hydrothermal method, which greatly improved the photocatalytic degradation efficiency of tetracycline hydrochloride and photocatalytic cycle stability compared with pristine 1T/2H‐MoS2. The highest photodegradation efficiency of 70.8% is achieved when the molar ratio of 1T/2H‐MoS2 to cadmium sulfide is 1:4. The capture experiment indicates that hydroxyl radical (⋅OH) and superoxide radical (⋅O2−) play a role in the photocatalytic degradation process. A Z‐type heterojunction may be formed on the 1T/2H‐MoS2/CdS composite based on a series of analyses, which improves the photocatalytic performance effectively via expanding the range of light response and promoting the separation of photogenerated electrons and holes. This work provides an alternative to constructing novel Z‐scheme photocatalysts with high performance in the absence of noble metals.

Constructing a CeFeO3/LaFeO3/ZnIn2S4 double Z-scheme heterojunction for photocatalytic atrazine degradation under visible light irradiation

The limited light absorption range and rapid recombination of interfacial charges were deemed to be the main restriction of the photocatalysts for atrazine (ATZ) degradation, and the construction of Z-scheme heterojunction was an effective strategy. Herein, a CeFeO3/LaFeO3/ZnIn2S4 (CFO/LFO/ZIS) double Z-scheme ternary heterojunction photocatalyst was fabricated by the in-situ precipitation and hydrothermal method. The photocatalytic ATZ degradation efficiency of optimized heterojunction reached 52% within 175 min under visible light irradiation, which was 3.1, 3.7 and 1.7 times higher than that of CFO, LFO and ZIS, respectively. The enhanced photocatalytic activity was due to the excellent light capture capacity and improved photogenerated charge separation in CFO/LFO/ZIS double Z-scheme heterojunction photocatalyst. Meanwhile, some environmental factors on the influence of photocatalytic ATZ degradation performance were systematically investigated. Quenching experiments confirmed that ·OH, h+ and 1O2 were the main active species during the photocatalytic ATZ degradation process. The possible photogenerated charge separation route was proposed via the analysis of the IEF effects between CFO, LFO and ZIS. Finaly, the possible ATZ degradation pathway was deduced by LC-MS measurement and toxicity assessment of the intermediates were also evaluated by the Toxicity Estimation Software Tool (TEST). This work not only provided a potential magnetic recyclable ferrate based double Z-scheme heterojunction photocatalyst for enhancing photogenerated charge separation and light absorption, but also evaluated the intermediate toxicity and related environmental factors on the activity of photocatalyst, which was facilitating the practical application for the degradation of ATZ.

Hydrothermal Synthesis of CuO/WO3 Hybrid Bifunctional Composites with Unprecedented Dark Adsorption and Photocatalysis

AbstractThis study presents the synthesis and characterization of Copper Oxide/Tungsten Oxide (CuO/WO3) hybrid bifunctional composites using a hydrothermal approach. X‐ray diffraction (XRD) analysis confirms the successful synthesis of CuO/WO3 hybrids, exhibiting additional peaks corresponding to WO3 phases. Scanning electron microscopy (SEM) images reveal well‐defined, aggregated particles with a nanoscale pattern and uniform distribution of CuO and WO3 throughout the composite. Energy‐dispersive X‐ray spectroscopy (EDX) confirms the stoichiometric composition of CuO/WO3 hybrids. Evaluation of dark adsorption and sunlight‐assisted photocatalysis using methylene blue (MB) dyes shows a remarkable enhancement in efficiency compared to pristine CuO. The CuO/WO3 hybrids exhibit a dark adsorption capacity of 87 % and a photocatalytic degradation efficiency of 95 % under sunlight illumination, outperforming pure CuO. These results underscore the synergistic interaction between CuO and WO3, facilitating efficient pollutant removal. The study elucidates the structural properties and mechanistic insights driving the superior performance of CuO/WO3 hybrid composites, offering promising prospects for advanced water treatment technologies.

A high-efficiency clay mineral based organic photocatalyst towards photodegradation of butyl xanthate in mineral processing wastewater

The organic solar cell active layer, well known for excellent visible light response capability, is regarded as a potential candidate for photocatalytic degradation of organic wastewater. However, the poor dispersibility in water due to its hydrophobicity property severely limited the degrading efficiency. In this work, a novel composite photocatalyst PM6:IDT8CN-M/CK2 with a broad visible absorption spectrum and non-toxicity was first synthesized through the intercalation compounding method. A good dispersibility of PM6:IDT8CN-M in wastewater was achieved with the help of rich interlamellar porosity and good hydrophilicity of calcined kaolin. This composite photocatalyst was successfully applied to the SBX photocatalytic degradation in mineral processing wastewater, and the SBX pollutants can be completely degraded within 10 min under the condition of visible light irradiation. Compared with other reported photocatalysts, the photocatalytic degradation efficiency of SBX was dramatically improved by at least seven times. Moreover, PM6:IDT8CN-M/CK2 has remarkable stability, sustaining degradation efficiencies of over 90 % in 60 cycles. Notably, the organic solar cell active layer in PM6:IDT8CN-M/CK2 can achieve carrier rapid separation and transport, enhancing the generation of active oxides (∙O2–, and ∙OH, etc.). At the same time, the large surface area of PM6:IDT8CN-M/CK2 provides a suitable environment for the oxidation reaction of active radicals with SBX to achieve this efficient photocatalytic degradation. Overall, this work not only extends the application scope of organic solar cell active layer, but also develops a high-efficiency SBX removal technique for the treatment of mineral processing wastewater.

Construction of functionalized In-based metal organic framework/BiOCl1−xIx Z-scheme heterojunction for efficient photocatalytic degradation of tetracycline: Performance and mechanism

The environmental implications of antibiotics have drawn widespread attention. Numerous monomer-based bismuth oxide halide catalysts have been extensively studied to remove tetracycline (TC) from aquatic environments. Integrating bismuth oxide halide composites with In-based metal organic framework (NH2-MIL-68(In)) might potentially serve as a novel strategy. By meticulously adjusting Cl and I within the composite bismuth halide oxide (B-x), a suite of purpose built heterojunctions (NMB-x) were synthesized, which were engineered to facilitate the efficient photodegradation of TC in simulated and actual aquatic environments. The incorporation of Z-scheme heterojunctions yielded a significant enhancement in photocatalytic responsiveness and charge carrier separation. Notably, NMB-0.3 demonstrated remarkable TC removal efficiency of 88.52 ± 3.05%, which is 3.74 times of B-0.3 within 90 min. The apparent quantum yield was also increased from 8.97% (B-0.3) to 19.68% (NMB-0.3). The removal of TC from natural water bodies was also assessed. Moreover, the photocatalyst concentration, assessed using response surface method, was found to show influential factors on TC removal. In addition, density functional theory (DFT) simulations were employed to identify vulnerable sites within TC. Intermediates and pathways in the photodegradation of TC have also been inferred. Furthermore, a comprehensive environmental toxicity assessment of representative intermediates demonstrated that these intermediates exhibited significantly reduced environmental toxicity compared to TC. This study provides a new approach to the design strategy of efficient and environmentally friendly MOF-based photocatalysts.

Construction of La2O3/AgCl S-scheme heterojunction with interfacial chemical bond for efficient photocatalytic degradation of bisphenol A

The formation of interfacial chemical bonds in S-scheme heterostructure is a crucial factor to realize efficient interfacial charge transfer. High-energy mechanical ball-milling is an effective method to form interfacial chemical bonds. In this work, an S-scheme La2O3/AgCl heterojunction catalyst was designed and prepared by ball-milling method. XPS, FTIR and Raman measurements showed that La-Cl chemical bond was formed at the interface of La2O3 and AgCl and an S-scheme charge transfer path mechanism existed in the La2O3/AgCl composite. The results of electrochemistry, photo-electrochemistry, capture experiments, free radical measurement and EPR verified that the S-scheme heterojunction and the interfacial La-Cl bond significantly accelerated the charge transfer rate between La2O3 and AgCl, and enhanced the photocatalytic capability of the composite catalysts. The degradation rate of bisphenol A by La2O3/AgCl heterojunction composite (LA50) reached 99 % in 20 min, and it also had excellent anti-interference ability and cycling stability. The toxicity of the degradation intermediates of bisphenol A was much less than itself, as calculated by TEST simulation. This work provided a promising strategy for improving the performance of S-scheme heterojunction catalysts by introducing interfacial chemical bonds as charge transfer channels.

Visible-light-driven photocatalytic degradation of doxycycline using TiO2/g-C3N4/BIOCHAR catalyst

Abstract TiO2/g-C3N4/biochar (TCNBC) catalysts were prepared by the hydrolysis method for the photocatalytic degradation of doxycycline antibiotic (DC), with biochar obtained from the pyrolysis of Phragmites australis. The catalysts were examined using scanning electron microscope (SEM), transmission microscopy (TEM), energy dispersive X-ray spectrometer (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL), and ultraviolet-visible diffuse reflectance spectroscopy (UV–Vis DRS) and nitrogen adsorption/desorption. The photocatalytic activity results showed that the TCNBC catalyst exhibited higher catalytic activity than pure TiO2 or g-C3N4. Its peak catalytic activity, achieving a decomposition efficiency of 91.93% and a mineralization efficiency of 81.50%, can be attributed to the synergistic effect of biochar, TiO2, and g-C3N4. Even after four cycles of use, the catalyst still maintained relatively high activity for the degradation of DC. The photocatalytic degradation efficiency of TCNBC decreased from 91.93% to 86.30% after four recycling events.

Photocatalytic degradation of four organophosphorus pesticides in aqueous solution using D-cys/Au NPs modified TiO2 by natural sunlight

The widespread use of organophosphorus pesticides (OPPs) in foods, poses a serious threat to human and environmental health, it is crucial to develop methods that can efficiently degrade residual OPPs. Herein, a chiral TiO2 photocatalyst was developed by modification TiO2 with D-cys/Au NPs (DAT) for the simultaneous degradation of four OPPs (chlorpyrifos, chlorpyrifos-methyl, malathion, and parathion) by natural light. The influence of D-Au NPs concentration on the degradation process was optimized, along with the initial pesticide concentration. Under optimal conditions, the photocatalytic degradation efficiencies of DAT for four OPPs were 96.7 %, 56.9 %, 42.6 %, and 49.2 %, respectively, after 12 h of natural light exposure. 12 degradation products of OPPs were identified, among which three products were identified for the first time. The degradation pathway revealed that the degradation of OPPs by DAT involves the oxidation of the P═S bond and the cleavage of the P-O bond and C-O bond. This study establishes a theoretical foundation for applying chiral TiO2 nanomaterials for the photocatalytic degradation of OPPs in foods.

Unraveling the potential of heteroanionic titanium oxycarbide photocatalysts for detoxifying SARS-Cov-2 antigen rapid test kit reagent solution in water sources

In the last few years, the COVID-19 pandemic has increased the usage of antigen rapid test (ART) kits and improper disposal of these kits has led to the mixing of toxic chemical compounds present in the ART reagent solution container into drinking water sources. When consumed with drinking water, these compounds can be harmful and toxic to both humans and aquatic life. Therefore, this research presents a study on the photocatalytic degradation of the Antigen Rapid Test-Reagent solution (ART-RS) using a single-phase titanium oxycarbide - TiO0.25 C0.75 (TiOC) photocatalyst synthesized through a solid-state reaction. The synthesized samples were studied using various characterization tools to analyze their structural, morphological, and optical characteristics. In the photocatalytic experiment, it was found that the synthesized titanium oxycarbide photocatalyst exhibited superior ART-RS degradation efficiency of 77% compared to commercial titanium dioxide (22%). The improved photocatalytic degradation efficiency of ART-RS is attributed to a combination of several factors. These factors include a narrower band gap, more efficient charge transfer kinetics, enhanced absorption of visible light, and an upward shift of the valence band (VB) edge in titanium oxycarbide. These collective effects contribute to the enhanced ART-RS photocatalytic degradation activity.

Effect of precursors on Cu particle distribution in g-C3N4 nanosheets towards efficient photocatalytic degradation and H2 generation

N-rich precursors govern the thermal polymerization formation of graphitic carbon nitride (g-C3N4) based catalysts towards enhanced photocatalytic performance. In this paper, Cu components were introduced in superior thin g-C3N4 nanosheets using the thermal polymerization copper acetate and bulk g-C3N4 created by different precursors including melamine, dicyandiamide, and thiourea, such as melamine-g-C3N4 (MCN), dicyandiamide-g-C3N4 (DCN), and thiourea-g-C3N4 (TCN). The performance of Cu-g-C3N4 nanosheets depended strongly on the precursors of bulk g-C3N4 samples. The well-developed Cu nanoparticles with clear lattice fringes were observed in the sample prepared using MCN (sample Cu-MCN) while the crystallinity of Cu nanoparticles became worse in the sample prepared using DCN (sample Cu-DCN). Interestingly, Cu clusters were homogeneously distributed in superior thin g-C3N4 nanosheets in the case of using TCN (sample Cu-TCN) because of S components in thiourea affected the thermal polymerization. The photocatalytic activity of Cu-TCN was drastically improved compared with other Cu-g-C3N4 samples. The photocatalytic hydrogen production rate of Cu-TCN with 1% of Cu components was 4035.6 μmol g-1 h-1. Cycle stability test indicated that sample Cu-TCN revealed high stability, in which the H2 generation rate was retained 95% of their initial value after 5 cycles. These results supply efficient approaches for the study and application of g-C3N4 based photocatalysts.

TiO2@Ti3C2Tx@ZnFe2O4-based long-lasting filter with photocatalytic activity

In the present work, the novel TiO2@Ti3C2Tx@ZnFe2O4 composites were synthesized by an ultra-sonicated method. The influence of MXene content and ZnFe2O4 nanoparticles on the photocatalytic performance and degradation efficiency of methylene blue (MB) solution were studied by different measurements such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Electrochemical impedance spectroscopy (EIS), and ultraviolet (UV)-visible spectroscopy. Among synthesized composites, the optimum photocatalyst showed excellent degradation efficiency of MB solution (100 % in 2 h) and high photocatalytic activity compared to the Ti3C2Tx and TiO2@Ti3C2Tx composites. The degradation mechanism of MB dye by TiO2@Ti3C2Tx@ZnFe2O4 composites was illuminated through kinetic studies. The results demonstrated the key role of ZnFe2O4 nanoparticles in dye removal. In addition, the optimum composite was deposited on nickel foam to construct a novel filter and photocatalytic measurements with long-time experiments had shown the stability and photocatalytic performance of the synthesized filter. Therefore, the optimal TiO2@Ti3C2Tx@ZnFe2O4 composite exhibits significant promise for practical water pollution degrading applications.

Facile construction of Bi2WO6/TiO2 microspheres heterojunction for boosting photocatalytic degradation of organic dyes

Flower-like Bi2WO6 microspheres and TiO2 spherical particles were prepared by a facile hydrothermal method without any surfactant or template. A unique Z-Scheme Bi2WO6/TiO2 heterojunction was successfully synthesized via a simple physical mixing method. The effect of mass ratio on the structure, morphology, optical properties, BET surface area and photocatalytic performance evaluated by degradation of organic dyes including Rhodamine B (RhB), methylene blue (MB) and methyl orange (MO) under solar irradiation was systemically investigated. When the mass ratio of Bi2WO6 to TiO2 was 1:4, the Bi2WO6/TiO2 composites exhibited the highest photocatalytic degradation efficiency, the highest degradation efficiency of RhB and MB reached 95.2 % and 89.3 %, which could be attributed to the construction of heterojunction structure between TiO2 and Bi2WO6. The optical absorption capacity of Bi2WO6/TiO2 composites was stronger than pure TiO2. Furthermore, the radical-quenching experiments proved that ·O2– and h+ played crucial roles in the photocatalytic reaction. The suitable band potential of Bi2WO6 (3.19 eV) and TiO2 (2.89 eV) revealed the Z-Scheme pathway and possible photocatalytic mechanism of Bi2WO6/TiO2 composites for organic dyes degradation. Thus, the direct Z-scheme Bi2WO6/TiO2 heterojunction effectively promoted separation of photogenerated electron-hole pairs, resulting in higher photocatalytic activity.

Ti-MOG derived TiO2 facet heterojunction rich in C/Ti3+/Ov for adsorption-photocatalytic removal of pharmaceutical pollutants from water

Developing efficient, stable, and broad-spectrum responsive photocatalysts is an effective way to degrade pharmaceutical pollutants in water. In this work, using concentrated hydrochloric acid (HCl) as a modulator, titanium metal–organic gel (Ti-MOG) was prepared and used as a template for calcination in air to obtain anatase TiO2 facet heterojunction rich in C/Ti3+/oxygen vacancy (Ov) (MOG-TiO2), which has a hierarchical porous structure, large specific surface area, and highly dispersed active site. Compared to P25, P25 + C and MIL-125(Ti) derived TiO2 (MOF-TiO2), MOG-TiO2 exhibited obviously enhanced adsorption-photocatalytic performance for tetracycline (TC) and low concentrations ethenzamide (ETH) under broad-spectrum light irradiation. The photocatalytic degradation efficiency of ETH by MOG-TiO2 reached 92.8, 100 and 98.7 % within 240, 60 and 6 min under Vis, UV and VUV light illumination, respectively, which were much higher than those of P25 (62.7, 33.2 and 73.0 %), P25 + C (61.7, 31.2 and 72.5 %) and MOF-TiO2 (79.2, 86.8 and 88.7 %). Furthermore, concentrated HCl promoted the formation of Ti3+/Ov in MOG-TiO2, which was conducive to the improvement of its photocatalytic performance. MOG-TiO2 also displayed great adsorption-photocatalytic stability and reusability. Moreover, the biotoxicity of TC toward E. coli DH5a obviously decreased after photocatalytic degradation. Based on the TiO2 facet heterojunction rich in C/Ti3+/Ov and the generation of hole, hydroxyl radicals, and superoxide radicals, the possible photocatalytic degradation mechanism of MOG-TiO2 was proposed. Overall, this work provides insights into constructing a novel hierarchical porous carbon-doped facet heterojunction photocatalyst for efficient pharmaceutical contaminants removal.

Controllable construction of hollow Fe3O4/Ag particles for microwave absorption and photocatalysis

Hollow metallic composite particles are widely used in microwave absorption and catalysis due to their unique cavity structures, and favorable physical and electromagnetic properties. In this work, we propose an approach to prepare highly dispersed Fe3O4/Ag composite particles with a hollow structure using water-soluble green template method combined with in-situ growth process. The as-prepared cubic Fe3O4/Ag composite particles with an average size of 3.19 μm of hollow Ag and 11.65 nm of Fe3O4 coating on the surface were used as fillers for preparing microwave absorption epoxy resin films, showing a minimum reflection loss of −62.37 dB at 16.63 GHz with 7.5 mm thickness. An effective absorption bandwidth of 4.80 GHz can be observed in the frequency bands of 4.70–6.09 and 14.59–18.00 GHz. This mechanism is attributed to the internal cavity of the Fe3O4/Ag particles realizing multiple reflections of electromagnetic waves, and the synergistic effect of Fe3O4 and Ag. Moreover, this perspective is confirmed by their photocatalytic performance. The Fe3O4/Ag particles achieve a high photocatalytic degradation efficiency of 99.84 % for Congo red dye within 30 min of light exposure and maintain a value of 96.62 % after 6 cycles, demonstrating an outstanding reusability.