Light Responsive Photocatalyst Research Articles

Efficient removal of ciprofloxacin by BiFe1−xCuxO3 for the photo assisted heterogeneous peroxymonosulfate activation

The study synthesized a series of novel solar light responsive photocatalysts, Cu-doped BiFeO3 perovskites (BiFe1−xCuxO3, BFCO), via a simple sol-gel method. Its effective application as peroxymonosulfate (PMS) activator under simulated solar irradiation towards ciprofloxacin (CIP) degradation was investigated. The as-prepared samples were characterized by various technologies such as XRD, TEM, BET, XPS, UV–vis DRS et al. The results revealed that Cu was successfully inserted into the BiFeO3 lattice and the Cu-doping could significantly reduce the optical band gap from 1.85 to 1.70 eV, as well as effectively facilitate the separation of electron-hole pair. Notably, the BiFe0.92Cu0.08O3 (0.08BFCO) exhibited the optimal catalytic performance and 80% of CIP could be degraded within 180 min with the addition of 1 mmol/L PMS and 0.6 g/L 0.08BFCO. By contrast, the reaction rate constant of 0.08BFCO was 1.8 times higher than that of pure BiFeO3. Free radical quenching experiments indicated that 1O2, ·O2− and h+ were the dominant active species involved in photocatalytic degradation. The excellent degradation performance could be ascribed to the synergy among 0.08BFCO photocatalyst and PMS activation. Moreover, 0.08BFCO maintained their photo-Fenton catalytic activity after three consecutive cycle reaction, indicating the excellent stability and recyclability of 0.08BFCO. Current study might propose new perspectives for the designing innovative metal doped photocatalysts towards the pollutant degradation assisted by solar light.

Surface Structures of Fe-TiO2 Photocatalysts for NO Oxidation.

Commercial rutile TiO2 particles capped with Al2O3 and ZrO2 layers, which are widely used in white pigments, can serve as a starting material for the fabrication of visible light-responsive photocatalysts toward gas-phase NO oxidation. The as-received TiO2 with iron impurities exhibited reduced photocatalytic activity, and the activity was boosted by the deposition of additional iron comparable in quantity to the intrinsic iron impurity level. Analyses using X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy, and low-energy ion scattering spectroscopy revealed that the deposited iron and intrinsic impurity iron are dissimilar in terms of location, oxidation states, and interaction with TiO2. This suggests that tracking the structure and impurity levels of photocatalyst elements can be crucial for understanding structure-activity relationships of real catalysts.

Structure–Property–Performance Relationships of Dielectric Cu2O Nanoparticles for Mie Resonance-Enhanced Dye Sensitization

A dye-sensitized photocatalytic (DSP) approach is considered as one of the promising approaches for developing visible light- and near-infrared light-responsive photocatalysts. DSP systems are still affected by significant drawbacks, such as low light absorption efficiency. Recently, it has been demonstrated that the plasmonic metal nanostructures can be used to enhance the light absorption efficiency and the overall dye-sensitization rate of DSP systems through the plasmonic Mie resonance-enhanced dye-sensitization approach. In this contribution, we report an alternate and novel approach, dielectric Mie resonance-enhanced dye sensitization. Specifically, we demonstrate that the dielectric Mie resonances in cuprous oxide (Cu2O) spherical and cubical nanostructures can be used to enhance the dye-sensitization rate of methylene blue dye. The Cu2O nanostructures exhibiting dielectric Mie resonances exhibit up to 1 order of magnitude higher dye-sensitization rate as compared to Cu2O nanostructures not exhibiting dielectric Mie resonances. Our model system developed from finite-difference time-domain simulation predicts a volcano-type relationship between the dye-sensitization rate and the size of Cu2O nanostructures. The predicted structure–property–performance relationship is experimentally verified, and the optimal size ranges of Cu2O nanospheres and nanocubes are identified. Although we demonstrate the dielectric Mie resonance-enhanced dye-sensitization approach using Cu2O nanostructures, the proposed approach can be used to design a wide range of DSP systems, including CeO2, α-Fe2O3, and TiO2 nanostructure-based DSP systems.

Phenyl-incorporated carbon nitride photocatalyst with extended visible-light-absorption for enhanced hydrogen production from water splitting

Developing and employing photocatalysts with extended visible-light-absorption has emerged as a fundamental issue for the enhanced capability of photocatalytic H2 evolution from water splitting. Herein, a wide-spectrum light-responsive phenyl-grafted carbon nitride photocatalyst was synthesized. It was found that benzonquanmine-derived g-C3N4 (BCN) exhibits significantly extended light absorption (∼670 nm) compared with conventional melamine-derived g-C3N4 (MCN). Correspondingly, the photocatalytic H2-evolution rate of BCN (2846 μmol h−1 g−1) is five times as that of MCN under visible-light irradiation. Particularly, an impressive H2-evolution rate of 58 μmol h−1 g−1 could be achieved on BCN even under light irradiation beyond 620 nm. The outstanding photocatalytic H2-evolution performance could be not only attributed to the enriched photons generated from the enhanced solar energy harvesting, but also to the distinctly inhibited rapid recombination of photogenerated electron-hole pairs resulting from the incorporation of phenyl groups. This work furnishes a new train of thought for the designing of carbon-nitride-based photocatalysts with enhanced capability of visible-light-utilization.

Polymeric iron phthalocyanine/g-C3N4 composite catalyst by mechanical force enhanced stripping and recombination for solar-induced contaminant degradation and CO2 reduction

Solar light response photocatalysts have been extensively studied to alleviate energy crisis and solve environmental pollution problems. Herein, polymerized iron phthalocyanine (FePPc) was prepared and then compounded with graphitic carbon nitride (g-C3N4) by ball milling to obtain FePPc/g-C3N4 composite photocatalyst. During the ball milling process, FePPc was mechanically exfoliated and compounded with g-C3N4, which the binding mode mainly relied on π-π stacking interaction with each other. Carbamazepine (CBZ) was completely removed within 15 min by FePPc/g-C3N4 under solar irradiation in the presence of peroxymonosulfate (PMS). Moreover, carbon dioxide (CO2) was also effectively reduced in the solar light responsive catalytic system with FePPc/g-C3N4 and the CO yield was 3388.98 µmol/g in 12 h. Compared with small molecule iron phthalocyanine (FePc)/g-C3N4, FePPc/g-C3N4 presented a significantly enhanced photocatalytic oxidation and reduction performance under solar light irradiation. Significantly, the visible light response of composite catalyst has been broadened due to FePPc sensitization, which reaching the near-IR light absorption band. Meanwhile, the compounding of photogenerated electron-hole pairs were efficaciously suppressed originating from the stronger bonding and greater electronic transfer between FePPc and g-C3N4. This work provides an effective basis for improving the utilization of sunlight in wastewater treatment and CO2 reduction.

Photocatalytic Filtration of Zinc Oxide-Based Membrane with Enhanced Visible Light Responsiveness for Ibuprofen Removal

The growing interest in mixed matrix membranes (MMMs) for developing photocatalytic membranes has provided a new direction in the search for efficient methods to concurrently separate and degrade contaminants. In this study, a visible light-responsive photocatalyst was blended into a polyvinylidene fluoride (PVDF) membrane casting solution to prepare PVDF-ZnO/Ag2CO3/Ag2O MMMs using the wet phase inversion method. The potential of ZnO/Ag2CO3/Ag2O as a photocatalytic component that is incorporated into the membrane was explored in detail under various loadings (0.5–2.91 wt%). The membranes were tested under ibuprofen (IBF) aqueous solution to analyze the membrane behavior in the synergistic combination of membrane filtration and photodegradation. The resulting PVDF-ZnO/Ag2CO3/Ag2O membrane with a rougher membrane surface area and excellent light harvesting capability showed higher photocatalytic filtration activity in removing IBF under visible light irradiations. The MMM fluxes demonstrated higher IBF fluxes than their initial fluxes at certain durations. This indicates that the membrane actively responds to light irradiation. The increase in the positive flux could be attributed to the photoinduced hydrophilicity generated by the ZnO/Ag2CO3/Ag2O photocatalyst, resulting in easier water layer formation and rapid transport through membranes. The highest IBF removal was demonstrated by the PVDF-ZAA2 membrane (1.96 wt% loading), with 49.96% of IBF removal within 180 min upon visible light irradiation. The reason for this lower IBF removal is that the UF membrane pores exceed the size of IBF molecules, thereby preventing the size exclusion mechanism. Thus, charge repulsion, hydrophobic adsorption, and photocatalytic activity were considered along with the IBF removal of the photocatalytic membranes. However, the recyclability of the PVDF-ZAA2 photocatalytic membrane showed a great improvement, with 99.01% of IBF removal recovery after three cycles. These results highlight the potential of such hybrid membranes in mitigating membrane fouling by providing a platform for photocatalysts to continuously degrade pollutants present in such wastewaters. Therefore, the hybridization of a photocatalyst and membrane provides insight that could be utilized to improve and retrofit current water effluent treatment methods.

Fabrication of 3D flower-like OVs-Bi2SiO5 hierarchical microstructures for visible light-driven removal of tetracycline

Visible light responsive flower-like Bi2SiO5 photocatalysts with ample oxygen vacancies (OVs) were synthesized via a template-free solvothermal treatment process. Notably, the content of OVs on Bi2SiO5 sample prepared can be facilely adjusted by calcination Bi2SiO5 at the different temperature. Among all the samples, the content of OVs on the pristine Bi2SiO5 is the highest, confirmed by XPS and EPR characterization. The photocatalytic efficiency of OVs-Bi2SiO5 for detoxification of tetracycline (TC) is 2.6 times of that of Bi2SiO5-550 (the pristine Bi2SiO5 was calcined at 550 °C in air atmosphere). OVs can establish a new defective energy level in energy level of Bi2SiO5, inducing OVs-Bi2SiO5 absorbs visible light. Moreover, introduction of OVs facilitates the generation of superoxide radical (•O2–) by activation of O2 with the assistance of photoinduced electrons. Bi2SiO5 with rich OVs can effectively destruct tetracycline under visible light irradiation.

Structural and Chemical State Analyses on Nitrided GaOOH as a Visible Light Response Photocatalyst

To prepare photocatalysts promoting water splitting under visible light irradiation, GaOOH was nitrided by the calcination at a temperature ranging from 773 to 1273 K under a NH3 flow to produce nitrogen doped Ga2O3. X-ray diffraction measurements suggested that even under NH3 atmosphere dehydration of GaOOH to α-Ga2O3 occurred by calcining below 873 K. In the samples nitrided above 973 K, gallium nitride (GaN) phase started to appear and the crystallinity became better with increasing the nitriding temperature. In diffuse reflectance ultraviolet-visible measurements, absorption bands appeared in the visible light region after the nitrization, and the shift of the absorption edge with nitriding temperature suggested the formation of a new phase like gallium oxy-nitride. X-ray photoelectron spectroscopy and scanning transmission electron microscopy-electron energy-loss spectroscopy analyses revealed that oxygen atoms were distributed homogeneously and mixed with nitrogen atoms in the sample nitrided at 1173 K [referred as S(1173 K)] while oxygen atoms were mainly distributed at the surface of the sample nitrided at 1273 K [S(1273 K)]. The differences in the composition and chemical state near the sample surface closely related to the activity and stability during water splitting reaction under visible light irradiation between S(1173 K) and S(1273 K), i.e., the former sample provided stable H2 and O2 evolution while the latter sample was inactive and unstable.

Facile fabrication of ZnO decorated ZnFe-layered double hydroxides @ biochar nanocomposites for synergistic photodegradation of tetracycline under visible light

To explore effective treatment of antibiotics-contaminated water using visible light-responsive photocatalyst, a series of ZnO decorated ZnFe-layered double hydroxide @ biochar (ZnO/ZnFe-LDH@BC) nanocomposites were obtained via a facile hydrothermal method. The fabricated nanocomposites exhibited uniform distribution of ZnO/ZnFe-LDH on BC matrix, allowing more active sites of ZnO/ZnFe-LDH to be utilized. The BC matrix brought widened visible-light absorbance, narrowed bandgap, and improved charge separation and transfer. During photocatalytic degradation of tetracycline (TC) under visible LED light, the nanocomposites showed significant enhancement of degradation efficiency, compared to ZnO/ZnFe-LDH or BC alone, indicating a strong synergy between ZnO/ZnFe-LDH and BC. The nanocomposite containing 23.0 wt% of BC (ZnO/ZnFe-LDH@BC0.2) showed optimal performance (achieving 87.7% of degradation within 4 h) in comparison to the reported LDHs@carbon photocatalysts. Alkaline condition and co-existing CO32– ions could enhance the stability and recyclability of the nanocomposites. Additionally, the possible degradation pathway of TC was analyzed via LC-MS and the reduction in toxicity resulting from photocatalytic degradation was confirmed by the culture of mung bean sprouts. This study provides a rational design strategy and performance assessment of LDH-based nanocomposites for the treatment of antibiotics-contaminated water.

One-pot loading of cadmium sulfide onto tungsten carbide for efficient photocatalytic H2 evolution under visible light irradiation

In an attempt to construct efficient photocatalytic H2 production system, designing a practical way to integrate co-catalyst and semiconductor is of great importance for future commercialization. Herein, we report a facile one-pot loading of CdS onto WC through the facile solid–liquid mixing method. The resultant visible light-responsive WC-supported CdS photocatalyst, at different WC wt.%, is assessed in photocatalytic hydrogen production, with lactic acid as an electron donor. Experimental results confirmed the positive effects of WC, with 3 wt% WC-loaded CdS photocatalyst (CdS/WC) exhibiting the highest hydrogen evolution rate of 9180 μmol h−1 g−1. Such achievement is associated to 2.1 and 43 folds activity improvements from that of CdS/Pt(3 wt%) and pure CdS photocatalysts, respectively. Meanwhile, an apparent quantum efficiency (AQE) of 14.3% was also recorded by the same photocatalyst from the single-wavelength photocatalytic reaction at 420 nm. All these enhancements can be attributed to the incorporation of WC, which extending and improving the light absorbability of CdS. Concurrently, the adjoining WC also provides rapid electron transfer channel and water reduction site, which facilitate the spatial separation of charges while promoting the kinetics of hydrogen production reactions. This study presents a facile synthesis method for CdS/WC photocatalyst, which offers high reliability for industrial scale hydrogen production.

Decontamination of ibuprofen micropollutants from water based on visible-light-responsive hybrid photocatalyst

Heterogeneous photocatalysis has caught attention in scientific community as an alternative and sustainable approach for environmental remediation. With that said, it is still a challenge to find affordable, photostable, harmless and chemically inert catalysts. In the present study, a novel visible light-responsive hybrid photocatalyst (AgBr/PSGCN-100) was synthesized via in-situ deposition precipitation that combines the phosphorus and sulfur co-doped graphitic carbon nitride (PSGCN) and AgBr particles. The as-synthesized samples were successfully characterized by various techniques including XRD, FT-IR, SEM, TEM, XPS, UV–vis DRS and PL. Compared to the other as-prepared samples and single photocatalysts, AgBr/PSGCN-100 performed well in terms of IBF photodegradation. Using 0.1 g AgBr/PSGCN-100, 0.5 mg/l, 1 mg/l, and 5 mg/l of IBF were completely degraded just in 20, 30, and less than 60 min of visible light irradiation, respectively; whereas 90% efficiency was achieved with increased IBF concentration (15 mg/L) in 100 min. As per trapping scavenger studies, the holes (h+) and superoxide radicals (•O2−) were the predominant reactive oxygen species for IBF degradation. However, hydroxyl radicals (•OH) also played a significant role. The good photocatalytic performance of AgBr/PSGCN-100 was linked to its heterostructure form. IBF intermediate products were analyzed by LC/MS-MS used negative electrospray ionization mode (ESI). We believe this study to be insightful in the rational design and best conception of heterostructure photocatalysts for environmental applications.

Synergistic impacts of composite formation and doping techniques to boost the photocatalytic aptitude of the BiFeO3 nanostructure

Reduced graphene oxide (rGO)-based rare-earth-doped metal oxide nanocomposites have shown exceptional photocatalytic efficiency for water splitting and remediation. In this study, we used a simple wet chemical technique to create gadolinium (Gd) doped bismuth ferrite (BiFeO 3 ) nanoparticles, which we then grafted onto an rGO using an ultrasonication strategy to create the nanocomposite (Gd-doped BiFeO 3 /rGO). The photocatalytic properties of the Gd-doped BiFeO 3 /rGO composite as produced were studied and compared to those of pure BiFeO 3 and Gd-doped BiFeO 3 . The photocatalytic capabilities of the three synthesized materials were tested by determining their effectiveness in removing methylene blue dye (MBD) from an aqueous solution at the expanse of solar irradiation. The Gd-doped BiFeO 3 /rGO showed notable photocatalytic efficiency compared to bare BiFeO 3 and Gd-doped BiFeO 3 samples. Specifically, the Gd-doped BiFeO 3 /rGO photocatalyst removed 87% MB dye (rate constant ∼ 0.016 min −1 ) after solar irradiation for 120 min, whereas the pure BiFeO 3 and Gd-doped BiFeO 3 samples degraded only 55% (rate constant ∼ 0.003 min −1 ) and 66% (rate constant ∼ 0.008 min −1 ) MB, respectively under the same conditions. The rGO based nanocomposite demonstrated excellent transient photocurrent response, which was 11-fold and 2.98-fold larger than pristine BiFeO 3 and Gd-doped BiFeO 3 , respectively. The increased photocatalytic activity of rGO-based photocatalysts may be attributed to the synergistic impact of Gd doping and rGO nanosheets inclusion, which results in a redshift in light absorption. Employed strategies suppressed electron-hole re-combination and charge-transfer resistance but boosted the electronic conductivity (due to the existence of conjugated -electrons) and diffusive properties (due to nanoarchitecture). Such an effective Gd-doped BiFeO 3 /rGO nanocomposite may give rise to novel pathways for achieving visible light response photocatalysts.

Practical Verification of Indoor Environment Improvement Effect of an Interior Wall Coated with Visible Light Responsive Photocatalyst

Practical Verification of Indoor Environment Improvement Effect of an Interior Wall Coated with Visible Light Responsive Photocatalyst

Synthesis, Property Characterization and Photocatalytic Activity of the Ag3PO4/Gd2BiTaO7 Heterojunction Catalyst under Visible Light Irradiation

A new type of Gd2BiTaO7 nanocatalyst (GBT) was synthesized by a high-temperature solid-phase method, and a heterojunction photocatalyst, which was composed of GBT and silver phosphate (AP), was prepared by the facile in-situ precipitation method for the first time. The photocatalytic property of GBT or the Ag3PO4/Gd2BiTaO7 heterojunction photocatalyst (AGHP) was reported. The structural properties of GBT and AGHP were characterized by an X-ray diffractometer, scanning electron microscope–X-ray energy dispersive spectra, an X-ray photoelectron spectrograph, a synchrotron-based ultraviolet photoelectron spectroscope, a Fourier transform infrared spectrometer, an UV-Vis diffuse reflectance spectrophotometer and an electron paramagnetic resonance spectrometer. The results displayed that GBT was well crystallized with a stable cubic crystal system and space group Fd3m. The lattice parameter or band gap energy of GBT was found to be a = 10.740051 Å or 2.35 eV, respectively. After visible light irradiation of 30 min, the removal rate of bisphenol A (BPA) reached 99.52%, 95.53% or 37.00% with AGHP as the photocatalyst, with Ag3PO4 and potassium persulfate (AP-PS) as photocatalysts or with N-doped TiO2 (NT) as a photocatalyst, respectively. According to the experimental data, it could be found that the removal rate of BPA with AGHP as a photocatalyst was 2.69 times higher than that with NT as a photocatalyst. AGHP showed higher photocatalytic activity for photocatalytic degradation of BPA under visible light irradiation compared with GBT or AP-PS or NT. The removal rate of total organic carbon (TOC) was 96.21%, 88.10% or 30.55% with AGHP as a photocatalyst, with AP-PS as photocatalysts or with NT as a photocatalyst after visible light irradiation of 30 min. The above results indicated that AGHP possessed the maximal mineralization percentage ratio during the process of degrading BPA compared with GBT or AP-PS or NT. The results indicated that the main oxidation radical was •OH during the process of degrading BPA. The photocatalytic degradation of BPA with AGHP as a photocatalyst conformed to the first-order reaction kinetics. This study provided inspiration for obtaining visible light-responsive heterojunction photocatalysts with high catalytic activity and efficient removal technologies for organic pollutants and toxic pollutants, and as a result, the potential practical applications of visible light-responsive heterojunction photocatalysts were widened. The subsequent research of thin-film plating of the heterojunction catalysts and the construction of complete photoluminescent thin-film catalytic reaction systems, which utilized visible light irradiation, could provide new technologies and perspectives for the pharmaceutical wastewater treatment industry.

Excellent dispersion of solar light responsive photocatalyst in the different polymer films for easy recycling and sustainable hydrogen production

This study successfully combined photocatalyst and polymer film with the facile method for enhancing recycling convenience, reducing second pollution, and applying sustainable hydrogen production by green technology. The different polymer photocatalyst films of polyvinyl alcohol/polystyrene platinum/nitrogen-doped titanium dioxide/strontium titanate composite (PVA/PNTSTO and PS/PNTSTO) films with excellent dispersion, high hydrogen production efficiency, and simple recycling were synthesized by solvent casting method. The results showed that Ti–O–C bonds not only combined the conjugated PVA with the PNTSTO photocatalyst but also transferred the electron from the conjugated PVA to the Pt/PNTSTO photocatalyst. The results demonstrated that when the photocatalyst concentration of PVA/PNTSTO and PS/PNTSTO was controlled at 2.5 wt%, it revealed the optimal hydrogen production efficiency (18,185 μmol h−1 g−1 and 10,889 μmol h−1 g−1) under simulated sunlight irradiation due to favorable dispersivity of the photocatalyst. PS/PNTSTO photocatalyst film relied on large pore to help the photocatalyst inside the film reacting with the reactants. Moreover, PVA-160T-2.5P and PS-2.5P photocatalyst films showed excellent stability for photocatalytic hydrogen production rate after 5 cycles. Therefore, the PVA/PNTSTO and PS/PNTSTO photocatalyst films were viewed as promising photocatalyst films for enhancing photocatalyst recycling convenience.

CuO-TiO2/graphene ternary nanocomposite for highly efficient visible-light-driven photocatalytic degradation of bisphenol A

To prepare a visible light-responsive photocatalyst of coupled CuO-TiO2 anchored on graphene oxide (CuO-TiO2/GO) nanocomposite, CuO-TiO2 photocatalyst was initially synthesized by surfactant assisted-sol-gel method and then anchored on GO via a simple hydrothermal process. The results of XPS, TEM, SEM and Raman analyses indicated that the being of CuO-TiO2 particles are decorated on the surface of GO effectively, accordingly resulting in the effective photo-generated charge separation, which was evaluated and supported via PL spectra and time-resolved PL spectra. The photocatalytic performance of CuO-TiO2/GO could also be improved via adjusting the proportion between CuO-TiO2 and GO. The best GO percentage is 10wt%, at which CuO-TiO2/GO composite exhibited the excellent BPA removal percentage of 56.5% compared with CuO-TiO2 photocatalyst (28.8%) after 300 min. of visible light. In addition, the postulated mechanism of the photocatalytic performance of this CuO-TiO2/GO ternary nanocomposite has been evaluated. The dominant reactive oxygen species (ROS) formed during the photocatalytic reactions were determined to be O2.− and .OH. The effect of the presence of anions on BPA degradation was also discussed in dept. While Cl− and NO3− have an inhibitory effect, HCO3− and CO32− have an accelerating and great improving effect towards photocatalytic degradation of BPA. This work indicates that this CuO-TiO2/GO hybrid ternary nanocomposite can also be performed as a highly potential photocatalyst in secondary treatments to degrade other organic pollutants.

Diclofenac degradation properties of a La-doped visible light-responsive TiO2 photocatalyst

Diclofenac (DCF), which is detected in the aquatic environment, can act as a harmful factor to the ecosystem and human health, but it is difficult to remove it with existing water treatment methods. DCF can be removed using the TiO2 photocatalysis process, and in this study, a method for removing it using visible light was sought. A visible-light reactive TiO2 photocatalyst doped with lanthanum (La) was synthesized using an LPP (Liquid Phase Plasma) process, and the photocatalytic activity was investigated by decomposing diclofenac. La was doped uniformly into the TiO2 powder, and the content of doped La increased with increasing concentration of the initial precursor. The La dopant was in the form of La2O3, and the bandgap and photoluminescence intensity decreased with increasing amount of doped La. In the photolysis experiment using a UV light source, the La-doped TiO2 photocatalysts (LDTPs) showed slightly higher activity than the bare TiO2, but the photocatalyst activity of the LDTPs under the visible light irradiation was superior. In the degradation experiment of DCF by LDTP, four major by-product intermediates were detected. Moreover, it was estimated that degradation proceeded through two pathways: hydroxylation and ring closure.

Ultrasonic assisted anchoring of Yb2O3 nanorods on In2S3 nanoflowers for norfloxacin degradation and Cr(VI) reduction in water: Kinetics and degradation pathway

The design and fabrication of environmentally benign, visible light-responsive heterojunction photocatalysts remain a viable route towards sustainable exploitation of photocatalysis for water treatment. In this contribution, binary nanostructures consisting of varying ratios of In2S3 and Yb2O3 (In2S3/Yb2O3) were obtained via a two-step method involving hydrothermal synthesis and ultrasonic treatment. The prepared materials were characterised extensively to reveal information about their morphology, optical properties, phase composition, chemical states and electrochemical properties. Subsequently, the nanocomposite photocatalysts were investigated for their dual role of photooxidation of the emerging pollutant; norfloxacin (NFX) and photoreduction of the toxic heavy metal; Cr(VI) in spiked water samples. The photocatalytic activity of the nanocomposites was found to be dependent on the photocatalyst composition (ratio of In2S3:Yb2O3) and dose, contact time and initial concentration of the pollutant. Under optimised conditions, Cr(VI) reduction efficiency reached 96.4% in just 45 min of visible light irradiation and the degradation rate is 28.84 times and 3.90 times higher than that of Yb2O3 and In2S3, respectively. Equally, over 95.0% NFX degradation was achieved in 50 min, under optimal conditions. The enhanced activity is credited to efficient visible light absorption, remarkable charge separation and transfer, leading to increased lifetime of the photogenerated charge carriers. Moreover, the possible degradation route for NFX was crafted based GC-MS analysis. Finally, the photostability and recyclability of the composite photocatalyst was probed and a plausible charge transfer mechanism was proposed. This work demonstrates the effectiveness of the ultrasonication method for preparing binary nanostructures and the versatility of the photocatalysts towards detoxification of both organic and inorganic pollutants in water.

Pumice-supported ZnO-photocatalyzed degradation of organic pollutant in textile effluent: optimization by response surface methodology, artificial neural network, and adaptive neural-fuzzy inference system

A heterogeneous photocatalysis was adopted to treat textile industry effluent using a combination of pumice-supported ZnO (PUM-ZnO) photocatalyst and solar irradiation. The visible light-responsive PUM-ZnO photocatalyst was prepared via the impregnation method and characterized using various spectroscopic techniques. The photocatalytic degradation process was modeled via response surface methodology (RSM), artificial neural network (ANN), and adaptive neuro-fuzzy inference system (ANFIS), while the optimization of the three independent parameters significant to the photocatalytic process was carried out by a genetic algorithm (GA) and RSM methods. The low standard error of prediction (SEP) of 0.56-1.75% and high coefficient of determination (R2) greater than 0.96 for the models developed indicated that they adequately predicted the photodegradation process with high accuracy in the order of ANFIS > ANN > RSM. The process optimization results from the developed models showed that GA performed better than RSM. The best optimal condition (3.29g/L catalyst dosage, 45.85min irradiation time, and 3.13 effluent pH) that resulted in maximum degradation efficiency of 99.46% was achieved by the ANFIS model coupled with GA (ANFIS-GA).

Boosting the photocatalytic hydrogen production performance of graphitic carbon nitride nanosheets by tailoring the cyano groups

Graphitic carbon nitride (g-C3N4) is a promising visible light responsive photocatalyst for solar hydrogen production. However, pristine g-C3N4 suffers from severe charge recombination, resulting in a poor photocatalytic activity. Herein, a facile KOH-assisted sealed heating process is designed to tailor the electronic structure of g-C3N4, leading to a significantly enhanced and stable photocatalytic hydrogen production rate of 225.1 µmol h−1 using only 50 mg of the photocatalyst. An excellent apparent quantum efficiency of 16.82% is achieved at 420 nm. Systematic studies reveal that KOH-assisted sealed heating can generate more cyano groups onto the framework of g-C3N4, which can increase the charge carrier density and reduce the surface charge transfer resistance, promoting charge separation and transfer. The new findings demonstrated in this work provide a facile strategy for the design of low-cost and efficient photocatalyst for solar fuel production.