Photocatalytic Activity Tests Research Articles

Aminoacid functionalised magnetite nanoparticles Fe3O4@AA (AA = Ser, Cys, Pro, Trp) as biocompatible magnetite nanoparticles with potential therapeutic applications

Magnetic nanoparticles (MNPs) are of great interest for their wide applications in biomedical applications, such as bioimaging, antitumoral therapies, regenerative medicine, and drug delivery. The work aimed to obtain biocompatible magnetite nanoparticles coated with amino acids of the general formula Fe3O4@AA (AA = L-tryptophan, L-serine, L-proline and L-cysteine) for potential therapeutic application in anticancer drug delivery. The obtained materials were characterised using XRD, FTIR, DLS analysis, SEM, thermogravimetry (TG), differential scanning calorimetry (DSC), and UV–vis spectroscopy. The photocatalytic, cytotoxic and antimicrobial activity tests of the obtained materials were carried out. The choice of amino acid determines the properties of the material and its future use, for example, Fe3O4@Cys supports radical production, which may increase the efficiency of catalytic degradation, while tryptophan captures radicals, which may be an advantage in several biomedical applications. Fe3O4@Trp exhibited good antimicrobial activity (MBEC and MIC) against E. coli ATCC 25922, P. aeruginosa ATCC 27853 and C. albicans ATCC 10231 while Fe3O4@Pro exhibited the best results against S. aureus ATCC 25923.

Correlating Cu dopant concentration, optoelectronic properties, and photocatalytic activity of ZnO nanostructures: experimental and theoretical insights

The photocatalytic activity of photocatalysts can be enhanced by cation doping, and the dopant concentration plays a key role in achieving high efficiency. This study explores the impact of copper (Cu) doping at concentrations ranging from 0% to 10% on the microstructural, optical, electronic, and photocatalytic properties of zinc oxide (ZnO) nanostructures. The x-ray diffraction analysis shows a non-linear alteration in the lattice parameters with increasing the Cu content and the formation of CuO as a secondary phase at the Cu concentration of >3%. Density functional theory calculations provide insights into the change in the electronic structures of ZnO induced by Cu doping, leading to the formation of localizeddelectronic levels above the valence band maximum. The modulation of the electronic structure of ZnO by Cu doping facilitates the visible light absorption via O 2p → Cu 3d and Cu 3d → Zn 2p transitions. Photoluminescence spectroscopy reveals a quenching of the defect-related emission peak at approximately 570 nm for all Cu-doped ZnO nanostructures, indicating a reduction in the structural and other defects. The photocatalytic activity tests confirm that the ZnO nanostructures doped with 3% Cu exhibit the highest efficiency compared to other samples due to the suitable band-edge position and visible light absorption.

THE EFFECT OF NACL ADDITION TO TiO2/NiSe/NC PHOTOCATALYTIC FOR HYDROGEN GAS PRODUCTION

The widespread utilization of fossil fuel has resulted in fuel scarcity due to population growth and increased industrialization, driving the evolution of new renewable energy sources (NRE). Alternatively, hydrogen production through solar water splitting and TiO2 as a potential photocatalyst can be developed due to its good stability, environmental friendliness, and economic viability. However, TiO2 has the disadvantage of a wide bandgap that requires high energy and fast recombination. Therefore, in this research, TiO2/NiSe (TN) was synthesized with N doped carbon dopant modified with NaCl as a photocatalyst material through a solvothermal method. The characterized material using XRD, SEM, UV-DRS, BET, and FTIR. Photocatalytic activity tests were conducted to determine hydrogen production using an MQ8 sensor integrated with an Arduino microcontroller system. The synthesized materials are TN, TNC-0, and TNC-10. The addition of NaCl in carbon doped nitrogen materials of photocatalyst TNC-10 shows a reduction of the bandgap that is the lowest bandgap value obtained was 3.09eV. The photocatalytic activity test results showed a hydrogen production of 120 ppm for TNC-10, which is six-times higher compared to bare TiO2 as a photocatalyst. The increase in hydrogen gas production is due to the addition of NaCl to NC, which can enhance the photocatalytic activity and hydrogen adsorption on the catalyst surface during hydrogen production.

Effects of Nd-doping on crystal phase, structure and photocatalytic performance of TiO2 powders prepared by sol-gel method

Abstract In this work, 0.3–2 mol% neodymium (Nd) doped titanium dioxide (TiO2) powder was prepared by sol–gel method. The XRD showed that the anatase phase occur for the Nd doped TiO2 powders, and the Nd doping suppressed the original rutile phase for the pure TiO2 powder. SEM and TEM revealed that Nd doping reduced the tendency of severe aggregation and increased the specific surface area compare with pure TiO2 powder, and the Gibbs free energy difference did not reach the critical value of the phase transition driving force, while the adjustment of the Ti-O bond length caused by the addition of Nd3+ impeded the transformation of TiO2 to rutile phase. The photocatalytic activity test results for Methylene blue show that the 0.5 mol% Nd doped TiO2 had the best photocatalytic activity with the degradation efficiency of 96.2%.

Advanced photodegradation and antimicrobial performance: A comparative study of Al/Ag-Co-doped ZnO synthesis via laser assist chemical bath

This study utilizes a novel laser-assisted chemical bath synthesis (LACBS) approach to dope zinc oxide (ZnO) nanostructures with aluminum (Al) and silver (Ag), examining enhancements in photocatalytic and antimicrobial capabilities. The configurations tested include undoped ZnO, singly-doped ZnO(0.05) and ZnO(0.05), and co-doped ZnO:[Ag(0.025), Al(0.025)]. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses reveal shifts in lattice orientations and novel morphologies such as crumpled nano-flakes and interlocked flower-like formations. UV–visible spectroscopy results show a reduction in optical band gaps from 3.39 eV in undoped ZnO to 2.89 eV in co-doped samples. Photocatalytic activity testing under UV light reveals that undoped ZnO reaches a 68 % degradation efficiency of methylene blue over 10 min, while co-doped ZnO exhibits a superior 78.93 % efficiency under blue laser illumination. Antimicrobial assays indicate that co-doped ZnO inhibits Escherichia coli and Klebsiella pneumonia growth with zones of inhibition up to 40 mm, significantly larger than those observed with singly-doped or undoped samples. The integration of Al and Ag significantly enhances the crystalline structure, reduces the optical band gap by up to 0.50 eV, and increases both photocatalytic and antimicrobial effectiveness, marking substantial progress in the functional applications of ZnO nanostructures.

Interlinking the Fe doping concentration, optoelectronic properties, and photocatalytic performance of ZnO nanostructures

Doping is one of the effective strategies to modulate the optoelectronic properties and photocatalytic activity of photocatalysts. In this study, the effect of Fe doping (0–10 %) on morphology, optical and electronic properties, and photocatalytic activity of ZnO nanostructures is studied. The X-ray diffraction analysis shows that >5 % Fe doping, ZnFe2O4 is segregated as a secondary phase. The crystalline size decreases from 50.8 nm to 21.4 nm and the micro-strain increases with increasing the Fe concentration. The Fe doping-induced electronic restructuring facilitates visible light absorption through the O 2p → Fe 3d transition and the suppression of charge recombination by efficiently trapping conduction band electrons. Density functional theory (DFT) calculations are employed to unravel the underlying electronic changes induced by Fe doping in ZnO. The formation of shallow donor levels below the conduction band originates from the Fe 3d state. Photoluminescence spectra of pristine and Fe-doped ZnO nanostructures show characteristic emission peaks at approximately 384 nm and 570 nm, indicating the recombination of free excitons and oxygen interstitial defects, respectively. The results of the photocatalytic activity tests confirm that the 1 % Fe-doped ZnO nanostructures can exhibit the highest efficiency compared to the heavily doped ZnO nanostructures. The high efficiency in photocatalytic activity of 1 % Fe-doped ZnO nanostructures is ascribed to the modulated electronic structure and defect density. The adsorption affinity of methylene blue and water molecules to the surfaces of pristine and Fe-doped ZnO is simulated using the Monte-Carlo method. This study emphasizes the importance of controlling the dopant concentration to enhance the photocatalytic activity of various photocatalysts.

ELECTROSYNTHESIS OF Cu2O IN THE Cu(s)|CuSO4(aq)|Fe(s) REACTOR AND DEGRADATION POTENT FOR METHYLENE BLUE

Research on Cu synthesis2O uses the electrolysis method in the Cu(s)|CuSO4(aq)|Fe(s) system and degradation tests on methylene blue. Cu2O is a blackish-red solid which has properties as a semiconductor with a band gap of around 2-2.2 eV. These transition metal oxides are widely used as catalysts, solar cell components, and photodetectors. This research aims to synthesize Cu2O with variations in electrolysis time, determine the characteristics of Cu2O using FTIR and XRD, and test the degradation of methylene blue. The method used is electrolysis with a fixed potential and time variations. Research stages include solution preparation, determination of decomposition potential, electrolysis of samples under various conditions, and analysis. The results of determining the decomposition potential are used as the application potential value in the copper electrolysis process, namely 3.25 V. Sample electrolysis was carried out at a potential of 3.25 V, solution pH 4.0 in a volume of 100 mL at 30, 60, 90, and 120 respectively. and 150 minutes. The products obtained were analyzed using Fourier Transform Infra-Red (FTIR) and X-ray diffraction (XRD). The results of FTIR analysis show that before calcination there is a Cu-O functional group with a wave number of 477.23 cm-1 and after calcination, there is a Cu-O functional group with a wave number of 538.28 cm-1 which indicates the formation of oxide. The results of XRD analysis show that the value of 2θ before calcination is 36.553; 50,481 ; 62.855 which shows the peak of Cu and after calcination 29.928; 36,027 ; 61.568 shows the Cu2O peak. The highest photocatalytic activity test results for Cu2O against methylene blue were 85.96%. The rate of degradation of methylene blue by Cu2O follows the second order reaction rate equation with the R2 value and reaction rate constant being 0.9418 and 0.00769572 L mol-1 s-1, respectively.

SiO2 surface decorated TiO2 with tunable OVs and enhanced photocatalytic performance

In this study, silicon dioxide (SiO2) surface decorated TiO2 photocatalysts (SiO2/TiO2) were prepared by a hydrothermal method. The experimental results show that decoration of TiO2 by SiO2 can induce abundant OVs and improve the separation rate of photogenerated carriers. The light response range can be expanded from 320–390 nm to 320–420 nm, which improves the effective utilization of light and accelerates the formation of O2−. The existence of SiO2 induces surface effect, and promotes specific surface area of SiO2/TiO2. The photocatalytic activity test confirms that when the mass ratio of SiO2/TiO2 is 6 % (6 % SiO2), the photocatalyst has the strongest degradation ability for rhodamine B (RhB) and ciprofloxacin (CIP). The degradation rate constant of RhB and CIP on 6 % SiO2 is both 2.0 times of that on the reference TiO2. In light of the findings, photocatalytic mechanism of SiO2/TiO2 was reasonably interpreted.

Nanopartikel TIO2 Dari Ekstrak Daun Kemangi (Ocimum Sanctum) Untuk Degradasi Metilen Biru

The part of the basil plant is the leaves which have various types of benefits if studied further. With the introduction of secondary metabolites, it can be said that basil leaves contain eugenol compounds. The eugenol compound can be used as a reducing agent in the synthesis of TiO2 nanoparticles. The precursor used in the synthesis of TiO2 is titanium isopropoxide which has an oxidation state of +4. By utilizing the green synthesis method, TiO2 was reacted with basil leaf extract and then characterized using XRD and FTIR. The resulting particle size is 10.86 nm. And FTIR shows a wave number of 874.59 which represents the Ti-O functional group. Photocatalytic activity can take advantage of the synthesis of TiO2 nanoparticles by placing the nanoparticles in a methylene blue solution which has a concentration of 20 ppm and varies based on contact time and adsorbent mass. Photocatalytic activity testing obtained a degradation percentage of 79%-84% which varied based on adsorbant mass and contact time. Varying the adsorbant mass and time results in a degradation percentage that increases with each additional mass but will not increase again if it has reached the optimum phase and can reduce the degradation percentage.

Nano-ZnO prepared by using chaya and mango leaves extract for photocatalyst of methylene blue

This research aimed to synthesize nano-ZnO from chaya (Cnidoscolus aconitifolius) and mango leaves extract (Mangifera indica) as environmentally friendly photocatalysts. Nano-ZnO was synthesized using green synthesis, with leaves extracts as reducing agents and nanoparticle size stabilizers. The samples were prepared using two methods, namely nano-ZnO-1 and nano-ZnO-2. The results of Fourier transform infrared spectroscopy (FTIR) analysis showed the contribution of metabolite compounds in nano-ZnO synthesis. X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed the crystal size in nano range, with spherical nanorod morphology observed. Ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) determined the band gap energy of 2.97 eV and 3.17 eV. Furthermore, photocatalytic activity test showed that photocatalyst performance after 90 min was 68.86% (nano-ZnO-1) and 96.46% (nano-ZnO-2).

A magnetically recyclable Fe3O4/ZnIn2S4 type-II heterojunction to boost photocatalytic degradation of gemifloxacin

In this study, a magnetic recyclable Fe3O4/ZnIn2S4 flower-like heterojunction photocatalyst was successfully constructed by means of a hydrothermal method. It not only exhibited an enlarged the specific surface area, but also improved the absorption of visible light, which greatly enhanced the photocatalytic degradation ability. The results of the photocatalytic activity tests showed that the maximum rate (0.01903 min−1) of degradation of gemifloxacin (GMF) by Fe3O4/ZnIn2S4 was significantly increased by 1.67 and 23.79 times compared with those of pure ZnIn2S4 and Fe3O4, respectively. Based on the difference in Fermi energy levels between ZnIn2S4 and Fe3O4 and the electron gain/loss of the elements of the Fe3O4/ZnIn2S4 heterojunction, a type-II electron transfer mechanism was proposed to illustrate that the Fe3O4/ZnIn2S4 heterojunction improved the photocatalytic activity by promoting the separation and transfer ability of the photogenerated carriers. By combining liquid chromatography mass spectrometry -ion trap-time of flight technology and a condensed Fukui function, a possible degradation mechanism of GMF was proposed.

Synthesis of magnetite nanoparticles by controlled precipitation under oxidative atmosphere

Fe3O4 nanoparticles have been extensively studied due to their electromagnetic characteristics. Magnetite NPs can be produced by different methods. However, most of the methods use an inert atmosphere for synthesis. Therefore, this work aimed to produce magnetite NPs using the controlled precipitation method under an oxidant atmosphere. The synthesis was carried out using iron chloride, iron sulfate and ammonium hydroxide as reagents. Temperature, dripping time and stirring speed were the controllable variables. The NP powders were characterized by structural (XRD, FTIR), magnetic (vibrating sample magnetometry, VSM), and morphological (TEM) analyses. The results show particles ranging from 4 to 10 nm, with specific surface area of 52 m2/g and irregular morphology. The saturation magnetization (Ms) was 51.5 emu/g. The photocatalytic activity tests showed over 80 % discoloration of the methylene blue dye within 120 min. Therefore, the synthesis of magnetite NPs by the precipitation method under oxidative atmosphere was efficient.

Sensitization of TiO2 NPs with curcumin and chlorella and photocatalytic performance for degradation of phenol and organic dyes

Titanium dioxide (TiO2) is the most used semiconductor for heterogeneous photocatalysis. However, there is a limitation to its use because it is only activated under ultraviolet radiation (below 390 nm). Sunlight comprises only 5 % of UV radiation and consequently limits the use of TiO2 as a photocatalyst. Several studies were performed to extend the photocatalytic activity of TiO2 to the visible spectrum. Therefore, in this work two TiO2 NPs (S1 and P25) were sensitized with natural extracts to extend their photocatalytic activity to the visible light. In a previous work of our group TiO2 nanoparticles with a high surface area were synthesized via controlled precipitation method (called S1). In sequence they were wet sensitized with extracts of curcumin and Chlorella pyrenoidosa microalga to extend their photocatalytic activity to the visible light. After sensitization with natural extracts, the samples were characterized. The photoactivity of the NPs was evaluated for the degradation of phenol and the methylene blue, Rhodamine B and methyl orange dyes, under visible light using conventional LED lamps (380 to 780 nm). By XRD analysis all samples showed anatase and rutile as the only phases. The NPs sensitized with the highest content of chlorella and curcumin showed the highest mass loss (16 and 49 wt%, respectively), determined by DSC/TG, proving the adsorption of both extracts. Chemical bonds ascribed to both extracts were observed by the FTIR analysis. In addition, the NPs sensitized with the less content of the extracts presented the higher specific surface areas (∼207 m2/g, by BET analysis). The NPs are stable in water solution, presenting a zeta potential of −33 mV. Chlorella shows a larger absorption spectrum than curcumin. The calculated band gaps are 2.25 eV for chlorella and 2.07 eV for curcumin. Finally, the sensitization did not change the size or shape of the NPs (FESEM). The results of the photocatalytic activity tests show that the sensitized S1 NPs show higher efficiency than the commercial sensitized P25 NPs for the discoloration of the dyes, reaching 97 % for rhodamine B dye.

Enhancing Visible-Light Photocatalysis with Pd(II) Porphyrin-Based TiO2 Hybrid Nanomaterials: Preparation, Characterization, ROS Generation, and Photocatalytic Activity

Novel hybrid TiO2-based materials were obtained by adsorption of two different porphyrins on the surface of nanoparticles—commercially available 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and properly modified metalloporphyrin—5,10,15,20-tetrakis(2,6-difluoro-3-sulfophenyl)porphyrin palladium(II) (PdF2POH). The immobilization of porphyrins on the surface of TiO2 was possible due to the presence of sulfonyl groups. To further elevate the adsorption of porphyrin, an anchoring linker—4-hydroxybenzoic acid (PHBA)—was used. The synthesis of hybrid materials was proven by electronic absorption spectroscopy, dynamic light scattering (DLS), and photoelectrochemistry. Results prove the successful photosensitization of TiO2 to visible light by both porphyrins. However, the presence of the palladium ion in the modifier structure played a key role in strong adsorption, enhanced charge separation, and thus effective photosensitization. The incorporation of halogenated metalloporphyrins into TiO2 facilitates the enhancement of the comprehensive characteristics of the investigated materials and enables the evaluation of their performance under visible light. The effectiveness of reactive oxygen species (ROS) generation was also determined. Porphyrin-based materials with the addition of PHBA seemed to generate ROS more effectively than other composites. Interestingly, modifications influenced the generation of singlet oxygen for TPPS but not hydroxyl radical, in contrast to PdF2POH, where singlet oxygen generation was not influenced but hydroxyl radical generation was increased. Palladium (II) porphyrin-modified materials were characterized by higher photostability than TPPS-based nanostructures, as TPPS@PHBA-P25 materials showed the highest singlet oxygen generation and may be oxidized during light exposure. Photocatalytic activity tests with two model pollutants—methylene blue (MB) and the opioid drug tramadol (TRML)—confirmed the light dose-dependent degradation of those two compounds, especially PdF2POH@P25, which led to the virtually complete degradation of MB.

Green synthesis of a broad-spectrum UV-blocking bitumen modifier: Investigation of anti-aging performance and mechanism in bitumen

The popularization of inorganic nanomaterials doping, which serves as an effective method to improve the aging resistance of bitumen, is constrained by suboptimal lipophilicity and limited broad-spectrum UV absorption. To overcome this, we synthesized an environmentally-friendly, broad-spectrum UV-blocking nanocomposite by coating nano TiO2–ZnO (Nano-TZ) with sustainable lignin. TEM, T-IR, and photocatalytic activity test results indicate successful lignin coating on the Nano-TZ surface, with the optimal concentration being 15% (Nano-15L@TZ). Rheological test results demonstrated improved UV- and thermal-oxidative aging resistance of the Nano-15L@TZ-modified bitumen compared to those treated with uncoated nanomaterials. The synergistic modification mechanism of the Nano-15L@TZ composite was elucidated by combining the contact angle with UV–Vis and XPS VB tests. Nano-TZ exhibited broad-spectrum UV blocking properties that mitigated the UV aging of bitumen and lignin, while lignin effectively improved its compatibility with bitumen and captured radicals generated by Nano-TZ and aged bitumen.

Mn-N/C interfacial bridge accelerating electrons transfer of MnCO3/α-Ni(OH)2 to promote surface adsorbates activation for favorable photocatalytic NO oxidation

Photocatalytic technology has been proven to be an effective strategy for addressing NOx pollution. However, the lack of adsorbates activation ability of photocatalysts results in the formation of secondary toxic by-products. Herein, MnCO3/α-Ni(OH)2 composite photocatalyst was developed through one-pot hydrothermal method. The introduction of MnCO3 not only improves visible light absorption, but also generates new Mn-C and Mn-N interfacial bridge structures between the exposed Mn atoms of MnCO3 and the C/N functional groups of α-Ni(OH)2. This unique structure speeds up the migration of photogenerated electrons and holes, promoting surface-adsorbed O2 and NO co-activation. Photocatalytic activity test shows that MnCO3/α-Ni(OH)2 has enhanced NO oxidation activity without producing harmful NO2 by-products. This research offers a fresh perspective on the surface adsorbates activation to prevent secondary toxic by-product generation.

An effective way for the simultaneous valorization and treatment of olive mill wastewater by means of a photocatalytic process

This work hereby illustrates how to valorize olive mill wastewater (OMW) with a photocatalytic process able to produce hydrogen and simultaneously break down the polluting load of this waste. To achieve this objective, a comparison between the performances of commercial TiO2 and home-made sol–gel TiO2 on olive mill wastewater was first carried out. The hydrogen production and the ability of the catalyst to remove the organic matter present in wastewater were considered, with particular attention to the best combination (in terms of processing time and experimental phase sequence) between the anoxic phase (for the hydrogen production) and the oxidative phase (for the degradation of the organic residue). Once the best combination was identified, the photocatalyst in powder form was transferred on the surface of polystyrene pellets in order to make the catalyst easily separable and recyclable. The photocatalytic activity tests demonstrated that the proposed photocatalyst showed very good stability after ten reuse cycles, even in the presence of real OMW (with dilution 1:70), assuring a hydrogen production of about 16954 μmol/L. During the tests, the liquid samples were analyzed also with UHPLC technique that evidenced the phenol degradation and the presence of only hydroquinone as by-product.

Direct synthesis of TiO2 nanoparticles without heat treatment: Effect of order of addition and precursor/reducing ratio

Titanium dioxide (TiO2) is the most used semiconductor for heterogeneous photocatalysis. However, there is a limitation on its application since TiO2 works as catalyst only under ultraviolet radiation. Therefore, the synthesis of high-performance TiO2 NPs by a direct method without further calcination could improve the use of this catalyst. The current work aimed to obtain anatase/rutile TiO2 nanoparticles for photocatalysis under UV light by a direct method without further heat treatment. A 2k factorial design was used to evaluate the effect of the order of addition and ratio of the precursor/reducing agents on the synthesis of the NPs. TiO2 nanoparticles with large surface area were synthesized via the controlled precipitation method. The NPs were characterized by the XRD, DSC/TG, FTIR, BET, DLS, ELS, UV–Vis, FESEM-EDS techniques, and by the photocatalytic activity test. The commercial TiO2 NP P25 Evonik was used as standard photocatalyst for comparison with the obtained samples. The specific surface area (BET) of the TiO2 NP samples was three to five times higher in comparison to P25. The photoactivity of the TiO2 NP samples and P25 was determined as the discoloration of methylene blue and rhodamine B dyes under UVA radiation (330 nm, 12 W/m2) for 180 min. The results showed that the discoloration efficiency of the synthesized TiO2 NP samples is equivalent to that of the P25 sample. The synthesis of TiO2 nanoparticles via the controlled precipitation method using only two reagents proved to be a viable and promising route. The method does not require heat treatment for titanium dioxide crystallization and is still capable of producing a mixture of ideal phases to delay the recombination of the photogenerated electron-hole pair, contributing to the increase of the photocatalytic efficiency. The TiO2 NP samples will be used to the degradation of recalcitrant pollutants in water as textile dyes and pharmaceutical byproducts.

Hydrothermally synthesized CeO2/ZnO nanocomposite photocatalysts for the enhanced degradation of Reactive Orange 16 dye

In this work, in order to improve the photocatalytic efficiency of ZnO, the optimal CeO2 content in ZnO powders was determined by varying the quantity of CeO2 from 0 to 10 mol%. The structural, microstructural, optical, textural, and photocatalytic properties of the hydrothermally obtained ZnO and CeO2/ZnO nanocomposites have been investigated by using the XRPD, FESEM, HRTEM/SAED, BET, and UV–Vis techniques. Detailed characterization revealed that CeO2, having spherical nanodots of about 5 nm with a large surface area, was distributed onto the ZnO surface, whose crystallites displayed a bimodal distribution, from nano-to micro-crystals. The morphology of ZnO is a combination of nanograins and microrods that further makes a 3-D tie-like morphology. The nanocomposite containing 5 mol% of CeO2 showed about 30% better photocatalytic efficiency in the degradation of Reactive Orange 16 dye compared to other samples under simulated solar radiation. In addition, the kinetics and mechanism of photocatalytic degradation were also proposed based on the photocatalytic activity and scavenger tests.

Facile fabrication of NiWO4/ZnIn2S4 p-n heterojunction for enhanced photocatalytic H2 evolution

Construction heterojunction has been demonstrated to be a potential strategy to facilitate the activity of single component photocatalyst due to the enhanced light absorption, accelerated charge separation and so on. Herein, a NiWO4/ZnIn2S4 p-n heterojunction was prepared via a facile physical solvent evaporation method. In the binary system, the p-n heterojunction formed between NiWO4 and ZnIn2S4 can boost the charge separation. Besides, the introduction of NiWO4 can induce more electrochemically active surface area and decrease the overpotential of H2 evolution. In addition, the water angle contact (WAC) of ZnIn2S4 was reduced from 58.6° to 12.1°, suggesting a better hydrophilic surface. The photocatalytic activity tests indicated that the obtained composite exhibited excellent H2 evolution activity than NiWO4 or ZnIn2S4 alone. 10.7 %-NiWO4/ZnIn2S4 has a superior H2 production rate of 30.51 mmol·g−1·h−1, 4.42 folds higher than that of pure ZnIn2S4 (5.63 mmol·g−1·h−1). Meanwhile, the microstructure of 10.7 %-NiWO4/ZnIn2S4 is well preserved after reaction. This work provides experimental basis for the development of ZnIn2S4 based heterojunction for high-efficiency photocatalytic H2 evolution.