Unveiling the enhanced photoelectrochemical and photocatalytic properties of reduced graphene oxide for photodegradation of methylene blue dye

Graphene oxide (GO) and reduced graphene oxide (rGO) can act as metal-free photocatalysts to remove aqueous dye pollutants under light illumination. However, there is some disparity in past reports on the origin of the photoactivity of GO and rGO for photodegradation of dye pollutants. In this work, the photoactivity of GO and rGO for methylene blue (MB) dye photodegradation were investigated with photoelectrochemical (PEC) measurements. The optimized rGO sample (G-2) exhibited a stable photocatalytic rate, which was 2.5 times higher than that of pure GO. PEC measurements revealed that the photocatalytic activity of G-2 was elevated due to higher photocurrent density, higher charge carrier density, and better charge separation. The changes in band gap and band positions of rGO were determined through optical characterization and Mott–Schottky (M–S) plots. Finally, the photocatalytic degradation mechanism of GO and rGO on MB dye was determined.

Photoactivity of graphene oxide (GO) was enhanced after reduction, this is due to improved photoelectrochemical properties.     

2D–3D graphene-coated diatomite as a support toward growing ZnO for advanced photocatalytic degradation of methylene blue

In this work, a diatomite@graphene@ZnO (ZGD) photocatalyst was synthesized by chemical vapor deposition and hydrothermal methods and used for the photocatalytic degradation of methylene blue. The characterization of the prepared nanocomposite was performed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), and N₂ adsorption–desorption techniques. Ultraviolet-visible diffuse reflectance spectroscopy (DRS) showed that the prepared ZGD photocatalyst enhanced the absorption of visible light and induced a red-shift. Photoluminescence spectroscopy (PL) revealed that the recombination of electron and hole pairs can be effectively suppressed. Besides, the synergistic effect of diatomite and graphene avoids the agglomeration of ZnO, increases the number of surface adsorption sites, and limits the electron transport, consequently improving the photocatalytic activity of ZnO. When ZGD-3 was UV-irradiated (λ = 663 nm) for 90 minutes, the degradation effectiveness of methylene blue (MB) was 100%. After the fifth repetition, the photocatalytic degradation efficiency was always greater than 95%. Simply put, the ZGD nanocatalyst can be used as an efficient photocatalyst for dye wastewater treatment.

In this work, a diatomite@graphene@ZnO (ZGD) photocatalyst was synthesized by chemical vapor deposition and hydrothermal methods and used for the photocatalytic degradation of methylene blue.     

Novel TiO2/GO/CuFe2O4 nanocomposite: a magnetic,reusable and visible-light-driven photocatalyst for efficient photocatalytic removal of chlorinated pesticides from wastewater

A TiO₂/GO/CuFe₂O₄ heterostructure photocatalyst is fabricated by a simple and low-cost ball-milling pathway for enhancing the photocatalytic degradation of chlorinated pesticides under UV light irradiation. Based on the advantages of graphene oxide, TiO₂, and CuFe₂O₄, the nanocomposite exhibited visible light absorption, magnetic properties, and adsorption capacity. Integrated analyses using XRD, SEM, TEM, and UV-visible techniques demonstrated that the nanocomposite exhibited a well-defined crystalline phase, sizes of 10–15 nm, and evincing a visible light absorption feature with an optical bandgap energy of 2.4 eV. The photocatalytic degradations of 17 different chlorinated pesticides (persistent organic pollutants) were assayed using the prepared photocatalyst. The photocatalytic activity of the nanocomposite generated almost 96.5% photocatalytic removal efficiency of typical pesticide DDE from water under UV irradiation. The superior photocatalytic performance was exhibited by the TiO₂/GO/CuFeO₄ catalyst owing to its high adsorption performance and separation efficiency of photo-generated carriers. The photocatalyst was examined in 5 cycles for treating uncolored pesticides with purposeful separation using an external magnetic field.

A TiO₂/GO/CuFe₂O₄ heterostructure photocatalyst is fabricated by a simple and low cost ball milling pathway for enhancing the photocatalytic degradation of chlorinated pesticides under UV light irradiation.     

Removal of methylene blue dye by solvothermally reduced graphene oxide: a metal-free adsorption and photodegradation method

In this work, reduced graphene oxide (rGO) was fabricated at different reduction temperatures via an environmentally friendly solvothermal approach. The rGO formed at 160 °C clearly showed the partial restoration of the sp² hybridization brought about by the elimination of oxygenated functionalities from the surface. Owing to the augmented surface area and the band gap reduction, rGO-160 exhibited the best adsorption (29.26%) and photocatalytic activity (32.68%) towards the removal of MB dye. The effects of catalyst loading, initial concentration of dye, light intensity, and initial pH of solution were evaluated. It was demonstrated that rGO-160 could achieve a higher adsorptive removal (87.39%) and photocatalytic degradation (98.57%) of MB dye when 60 mg of catalyst, 50 ppm of dye at pH 11, and 60 W m⁻² of UV-C light source were used. The MB photodegradation activity of rGO-160 displayed no obvious decrease after five successive cycles. This study provides a potential metal-free adsorbent-cum-photocatalyst for the decontamination of dyes from wastewater.

A metal-free MB dye removal process was carried out by solvothermally synthesized rGO. After optimization, near-complete dye removal was achieved via an adsorption and UV photodegradation route.     

Preparation of S–N co-doped CoFe2O4@rGO@TiO2 nanoparticles and their superior UV-Vis light photocatalytic activities

A S–N co-doped CoFe₂O₄@rGO@TiO₂ (CFGT-S/N) nanocomposite was successfully synthesized via a facile vapor-thermal method. XRD, XPS, FT-IR and FETEM results confirmed that N and S were co-doped into the lattice of TiO₂. Photocatalytic tests indicated that CFGT-S/N exhibited excellent UV-Vis photocatalytic activity for decompositions of different organic dyes, including methyl orange (MO), rhodamine B (RhB) and methylene blue (MB). Particularly, the photocatalytic degradation rate of MO was about 33% higher than that when using P25 under visible light irradiation. The higher UV-Vis light photocatalytic activity of CFGT-S/N can be attributed to the synergetic effects of the strong absorption of visible light, the narrow band gap, improved separation of photo-generated electron/hole pairs, and the enhancement of the enrichment of pollutant dye molecules by S, N co-doping, CoFe₂O₄ and rGO. Moreover, this photocatalyst was superparamagnetic, which enables it to be easily recovered by an external magnetic field, and maintained stable photocatalytic efficiency over five cycles. Hence, CFGT-S/N with its highly efficient, recoverable and stable photocatalytic properties shows great potential for environmental treatment.

A magnetic recoverable S–N co-doped CoFe₂O₄@rGO@TiO₂ (CFGT-S/N) nanocomposite was synthesized via a facile vapor-thermal method. CFGT-S/N is an excellent UV-Vis photocatalyst because of the synergetic effects of S, N co-doping, the introduction of CoFe₂O₄ and rGO.     

Construction of stable bio-Pd catalysts for environmental pollutant remediation

It has been reported that Pd nanoparticles were a little weak to bind to the dried microbial (yeast) surface, leading to the poor stability of the bio-supported catalysts. The objectives of the study are to construct stable Pd nanocatalysts supported on the dried yeast surface with the help of a tiny amount (<0.1 wt%) of reduced graphene oxide (Pd/yeast/rGO) and apply the catalysts in environmental pollutant remediation. The characterizations of the as-obtained Pd/yeast/rGO catalysts showed that reduced GO could cover Pd/yeast materials and prepare 15–21 nm Pd nanoparticles under acid and base media. The catalytic performance of the Pd/yeast/rGO catalyst was compared with that of control Pd/yeast catalysts without GO. The results revealed the kinetic constant K_app in the reduction of 4-nitrophenol of Pd/yeast/rGO catalysts could reach 3.6 × 10⁻² s⁻¹ without stirring during the reaction, which was 2.4 times higher than that of Pd/yeast catalysts, and the Pd/yeast/rGO catalysts kept a good stability even after being reused in seven cycles. Furthermore, the catalysts also showed quite good catalytic activities on CO oxidation and decolorization of dye methylene blue (MB). Thus, Pd/yeast/rGO catalysts were proven to be highly active and stable for environmental remediation and have the advantage that they can prevent the loss of noble metals and be prepared conveniently from discarded microorganisms.

Stable bio-supported Pd/yeast/rGO catalysts were prepared by covering with a tiny amount (<0.1 wt%) of GO based on a non-enzyme reduction method.     

Preparation and characterization of Fe3O4@SiO2@TiO2–Co/rGO magnetic visible light photocatalyst for water treatment

In this work, Fe₃O₄@SiO₂@TiO₂–Co/rGO magnetic photocatalyst was successfully prepared by a sol–gel method and a hydrothermal method. The crystalline structure and performance of the resulting catalyst have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy and ultraviolet-visible light (UV-Vis) spectroscopy. The magnetic photocatalyst consists of Fe₃O₄@SiO₂@TiO₂–Co active particles and rGO carriers. The active particles have a double-shell core–shell structure with a size of about 500 nm and are supported on the rGO lamellae. TiO₂ doping with a small amount of metal Co and rGO can significantly improve the catalytic effect of magnetic photocatalyst, and rGO can also significantly improve the adsorption of pollutants by magnetic photocatalyst. The catalyst exhibited high photocatalytic activity in the degradation of methylene blue (MB) under visible light. 92.41% of this ability was retained after five times of repetitive use under the same conditions. The magnetic photocatalyst is easy to recover, and a recovery rate of 93.88% is still maintained after repeated use for 5 times.

With its low cost, high photocatalytic activity, high chemical stability and easy magnetic separation, Fe₃O₄@SiO₂@TiO₂–Co/rGO magnetic photocatalyst has a good application potential.     

Three-dimensional reduced graphene oxide aerogel stabilizes molybdenum trioxide with enhanced photocatalytic activity for dye degradation

By using three-dimensional reduced graphene oxide (rGO) aerogel as a carrier for molybdenum trioxide (MoO₃), a series of rGO-MoO₃ aerogels were synthesized by a self-assembly process. The results indicated that the as-prepared rGO-MoO₃ aerogel had very low density and good mechanical properties, and would not deform under more than 1000 times its own pressure. The rGO-MoO₃ aerogel showed more than 90% degradation efficiency for MB within 120 min. After six cycles of recycling, the degradation rate of MB only decreased by 1.6%. As supported by the electron paramagnetic resonance (EPR) measurements, the presence of the rGO aerogel enhanced electron conduction, prolonged carrier lifetime and inhibited electron and hole recombination, thus improving the photocatalytic efficiency of composite aerogel. Besides, the hydroxyl radical (OH˙) and radical anion (˙O₂⁻) played an important role in the photodegradation of the dye. The outstanding adsorption and photocatalytic degradation performance of the rGO-MoO₃ aerogel was attributed to its unique physical properties, such as high porosity, simple recycling process, high hydrophobicity, low density and excellent mechanical stability. The findings presented herein indicated that the rGO-MoO₃ aerogel had good application potential, and could serve as a promising photocatalyst for the degradation of dyes in wastewater.

By using three-dimensional reduced graphene oxide (rGO) aerogel as a carrier for molybdenum trioxide (MoO₃), a series of rGO-MoO₃ aerogels were synthesized by a self-assembly process.     

In situ synthesis of ZnO–GO/CGH composites for visible light photocatalytic degradation of methylene blue

A novel ZnO–GO/CGH composite was prepared using an in situ synthesis process for photodegradation of methylene blue under visible light illumination. The chitin–graphene composite hydrogel (CGH) was used to provide uniform binding of the nano ZnO–GO composite to the hydrogel surface and prevent their agglomeration. GO provides multi-dimensional protons and electron transport channels for ZnO with a flower-like structure, which possessed improved photo-catalytic activity. SEM analysis indicates that the hydrogel has good adsorption properties with rougher surfaces and porous microstructure, which enables it to adsorb the dyes effectively. Under synergetic enhancement of adsorption and photo-catalysis, catalytic activity and nano ZnO–GO/CGH recycling improved greatly. Synthesized nano ZnO–GO/CGH showed high dye removal efficiency of 99%, about 2.2 times that of the pure chitin gel under the same condition. This suggests the potential application of the new photocatalytic composites to remove organic dyes from wastewater.

A novel ZnO–GO/CGH composite was prepared using an in situ synthesis process for photodegradation of methylene blue under visible light illumination.     

Ionic-exchange immobilization of ultra-low loading palladium on a rGO electro-catalyst for high activity formic acid oxidation

A formic acid oxidation electro-catalyst with ultra-low palladium (Pd) loading was prepared via an ionic exchange method by utilizing the acidic functional groups on graphene oxide (GO). After simultaneous reduction of exchanged Pd²⁺ and residual functional groups on the GO surface, an ionic exchange reduced Pd catalyst supported on reduced GO (IE-Pd/rGO) was obtained. Three times improved formic acid oxidation mass activity compared with that of the conventional synthesized Pd/C catalyst was exhibited for the IE-Pd/rGO catalyst. More importantly, formic acid oxidation stability on the IE-Pd/rGO catalyst was remarkably improved due to synergistic effect of the strong immobilization of Pd nanoparticles and the effect of in situ doped N on the rGO support.

A formic acid oxidation electro-catalyst with ultra-low palladium (Pd) loading was prepared via an ionic exchange method by utilizing the acidic functional groups on graphene oxide (GO).     

Synthesis of Zn3(VO4)2/BiVO4 heterojunction composite for the photocatalytic degradation of methylene blue organic dye and electrochemical detection of H2O2

In this study, a Zn₃(VO₄)₂/BiVO₄ heterojunction nanocomposite photocatalyst was prepared using a hydrothermal route with different molar concentration ratios. The as-synthesized nanophotocatalyst was characterized using XRD, SEM, EDS, XPS, FT-IR, Raman, BET, UV-vis DRS, EPR and PL. The effect of molar ratio on composition and morphology was studied. The as-prepared nanocomposite exhibited excellent photocatalytic response by completely degrading the model pollutant methylene blue (MB) dye in 60 min at molar concentration ratio of 2 : 1. In basic medium at pH 12, the Zn₃(VO₄)₂/BiVO₄ nanocomposite degrades MB completely within 45 min. The nanocomposite was also successfully used for the electrochemical detection of an important analyte hydrogen peroxide (H₂O₂). This study opens up a new horizon for the potential applications of Zn₃(VO₄)₂/BiVO₄ nanocomposite in environmental wastewater remediation as well as biosensing sciences.

In this study, a Zn₃(VO₄)₂/BiVO₄ heterojunction nanocomposite photocatalyst was prepared using a hydrothermal route with different molar concentration ratios.     

Synthesis of Gd/N co-doped ZnO for enhanced UV-vis and direct solar-light-driven photocatalytic degradation

The construction of a UV-Vis and direct sunlight functioning photocatalyst is a puzzling task for organic pollutant removal. Herein, we have fabricated Gd/N co-doped ZnO nanoparticles for the first-time using a simple co-precipitation method for photocatalytic degradation application. The heteroatom doping enhances the light absorption ability and acts as a photo-induced electron–hole separator by creating a trap state. Co-doped ZnO shows comparatively high photocatalytic degradation efficiency of about 87% and 93% under UV-Vis and direct solar light respectively. Moreover, the prepared photocatalyst exhibits excellent stability for the recycling process. Hence, we believe that this heteroatom co-doped ZnO photocatalyst is an auspicious material for the photocatalytic organic pollutant degradation reaction.

The construction of a UV-Vis and direct sunlight functioning photocatalyst is a puzzling task for organic pollutant removal.     

Reduced graphene oxide-supported methylene blue nanocomposite as a glucose oxidase-mimetic for electrochemical glucose sensing

In this paper, a hybrid nanocomposite (MB-rGO) was synthesized based on the π–π stacking interactions between methylene blue (MB) and reduced graphene oxide (rGO). The as-synthesized nanocomposite was characterized by SEM, TEM, XRD, FTIR, UV-vis and XPS spectra. UV-vis spectroscopy and electrochemical tests suggested the MB-rGO modified on the electrode exhibited glucose oxidase-mimetic catalytic activity towards glucose, and displayed excellent electrocatalytic performance for electrochemical detection of glucose with a wide linear range from 1.04 to 17.44 mM, a low detection limit of 45.8 μM and a large sensitivity of 13.08 μA mM⁻¹ cm⁻². The proposed glucose sensor also showed high stability, reproducibility and good abilities of anti-interference to dopamine, ascorbic acid and uric acid. Moreover, the modified electrode was used to determine glucose concentration in human blood serum samples with satisfactory results.

A novel electrochemical glucose sensor based on methylene blue-reduced graphene oxide nanocomposite was constructed, and the sensor exhibited good glucose oxidase-mimetic electrocatalytic activity towards glucose and practical applicability.     

Effective photocatalytic degradation and physical adsorption of methylene blue using cellulose/GO/TiO2 hydrogels

Environmentally friendly cellulose/GO/TiO₂ hydrogel photocatalyst has been successfully fabricated via a green, simple, and one-step method and evaluated as the photocatalyst and adsorbent for the removal of methylene blue (MB). The XRD and FTIR analysis suggested the strong interaction among cellulose, GO and TiO₂, resulting from the formation of hydrogen bonds. Due to the unique porous structure of cellulose hydrogel and introduction of GO, the cellulose/GO/TiO₂ hydrogel showed superior (degradation ratio ∼ 93%) and reproducible (no significant change during the ten consecutive cycles) performance in the removal of MB under UV light. Consequently, the prepared cellulose/GO/TiO₂ hydrogel can be applied as an eco-friendly, high-performance, reproducible, and stable photocatalyst and adsorbent for the removal of MB. This green hydrogel is a promising candidate for dye wastewater treatment. Moreover, this work is expected to extend the scope of bio-templated synthesis of other nanomaterials for various applications.

New functional cellulose/GO/TiO₂ hydrogels are prepared via a simple method, showing superior and reproducible performance in the removal of MB.     

Highly stable binder free CNTs/rGO aerogel electrode for decolouration of methylene blue & palm oil mill effluent via electro-Fenton oxidation process

In this study, single wall carbon nanotubes (CNTs)/reduced graphene oxides (rGO) aerogels were prepared by a one-pot hydrothermal process without using a binder. The produced CNTs/rGO aerogel was used as cathode in electro-Fenton system for the decolouration of methylene blue (MB) and palm oil mill effluent (POME). The addition of CNTs increased the surface area, pore volume and conductivity of the rGO aerogel, which further enhanced their performance as cathode towards the decolouration of MB and POME via electro-Fenton reaction. Complete decolouration of MB using rGO aerogel without CNTs could not be achieved. The effect of electro-Fenton reaction parameters conducted using the aerogel samples including, current, electrolyte concentrations and pH, were investigated accordingly. The CNTs/rGO aerogel electrode also showed high stability and reusability for up to six consecutive treatment cycles for MB. Besides, the CNTs/rGO aerogel also showed good performance in treating POME with 69.8%, 47.6% and 58.1% of reduction in true colour, total organic carbon (TOC) and chemical oxygen demand (COD), respectively, via 60 minutes electro-Fenton reaction. This study showed that CNTs/rGO aerogels with high porosity and stability can be prepared using simple procedure without adding binder. This fully carbon-based aerogel can serve as effective cathode for decolouration of organic dye and effluent.

In this study, single wall carbon nanotubes (CNTs)/reduced graphene oxides (rGO) aerogels were prepared by a one-pot hydrothermal process without using a binder.     

Comparative photocatalytic activity of sol–gel derived rare earth metal (La,Nd, Sm and Dy)-doped ZnO photocatalysts for degradation of dyes

Rare earth metal doping into semiconductor oxides is considered to be an effective approach to enhance photocatalytic activity due to its ability to retard the electron–hole pair recombination upon excitation. Herein, we report the synthesis of different rare earth metal (La, Nd, Sm and Dy)-doped ZnO nanoparticles using a facile sol–gel route followed by evaluation of their photocatalytic activity by studying the degradation of methylene blue (MB) and Rhodamine B (RhB) under UV-light irradiation. Different standard analytical techniques were employed to investigate the microscopic structure and physiochemical properties of the prepared samples. The formation of the hexagonal wurtzite structure of ZnO was established by XRD and TEM analyses. In addition, the incorporation of rare earth metal into ZnO is confirmed by the shift of XRD planes towards lower theta values. All metal doped ZnO showed improved photocatalytic activity toward the degradation of MB, of which, Nd-doped ZnO showed the best activity with 98% degradation efficiency. In addition, mineralization of the dye was also observed, indicating 68% TOC removal in 180 min with Nd-doped ZnO nanoparticles. The influence of different operational parameters on the photodegradation of MB was also investigated and discussed in detail. Additionally, a possible photocatalytic mechanism for degradation of MB over Nd-doped ZnO nanoparticles has been proposed and involvement of hydroxyl radicals as reactive species is elucidated by radical trapping experiments.

In this study, we compared the photocatalytic activity of sol–gel derived rare earth metal (La, Nd, Sm and Dy)-doped ZnO photocatalysts by studying the degradation of MB and RhB under UV light irradiation.     

Photovoltaic and photocatalytic properties of bismuth oxyiodide–graphene nanocomposites

In this study, we evaluate the photovoltaic and photocatalytic properties of chemical vapor deposited bismuth oxyiodide (BiOI) and bismuth oxyiodide–graphene (BiOI–GR) nanocomposite thin films. The BiOI thin film has an average thickness of 574 nm and a bandgap of around 2 eV. The BiOI and BiOI–GR thin films exhibited nanoflake morphology. It was found that addition of graphene increases absorbance by causing vertical growth of nanoflakes, imparting anti-reflectance and light trapping properties. The photocatalytic activities of the thin films were evaluated by examining methylene blue (MB) degradation under visible light irradiation. BiOI–GR degraded 56.42% of MB in two hours while BiOI degraded 44.16%. Afterwards, FTO|BiOI|graphite|Al and FTO|BiOI–GR|graphite|Al solar cell devices were fabricated with photocurrent density values of 2.0 μA cm⁻² and 2.7 μA cm⁻², respectively. The improved properties of BiOI–GR are attributed to the anti-reflecting and light trapping properties of vertical BiOI–GR nanoflakes and the enhanced carrier separation due to graphene as an electron acceptor.

BiOI nanoflakes grown by air atmosphere chemical vapor deposition showed increased photocatalytic activity when deposited on a graphene coated substrate.     

Photocatalytic efficacy of supported tetrazine on MgZnO nanoparticles for the heterogeneous photodegradation of methylene blue and ciprofloxacin

MgZnO@SiO₂-tetrazine nanoparticles were synthesized and their photocatalytic efficiency was demonstrated in the decomposition of ciprofloxacin and methylene blue (MB). This new heterogeneous nanocatalyst was characterized by FT-IR, XRD, UV-vis, DRS, FE-SEM, ICP, and CHN. Distinctive variables including photocatalyst dose, pH, and degradation time were investigated. Up to 95% photodegradation was gained under the optimum conditions (20 mg photocatalyst, 3.5 ppm MB, pH 9) by using MgZnO@SiO₂-tetrazine nanoparticles after 20 min. An elementary kinetic study was carried out, and a pseudo-first-order kinetic with a reasonably high rate-constant (0.068 min⁻¹) was derived for the MB decay. Photoluminescence (PL) studies confirmed that the photocatalytic activity of MgZnO@SiO₂-tetrazine was almost consistent with the Taugh plots. Thus, it can be envisaged that the photocatalytic activity is closely related to the optical absorption. Furthermore, a photoreduction mechanism was suggested for the degradation process. Addition of scavengers and some mechanistic studies also revealed that O₂˙⁻ is the original radical accounting for the degradation of MB, considering this latter compound as a model type pollutant. Finally, efficacy of the present photocatalytic process was assessed in the degradation of ciprofloxacin as a model drug under the optimum reaction conditions.

MgZnO@SiO₂-tetrazine nanoparticle was synthesized and its photocatalytic efficiency was demonstrated in the decomposition of methylene blue (MB) and ciprofloxacin.     

Rational design of a polypyrrole-based competent bifunctional magnetic nanocatalyst

The combination of conducting polymers with semiconductors for the fabrication of organic/inorganic hybrid nanocatalysts is one of the most promising research areas for many applications. In this work, the synthesized nanocomposite combines several advantages such as the photoresponse shift from the UV region toward visible light by narrowing the band gap of the semiconductor, magnetic separation ability and dual applications including the catalytic reduction of p-nitrophenol (PNP) and the photocatalytic degradation of methylene blue (MB) dye. In addition to the core magnetite nanoparticles (NPs), the synthesized nanocomposite contains polypyrrole (PPY) and TiO₂ shells that are decorated with silver metal NPs to prevent electron–hole recombination and to enhance the catalytic performance. Indeed, the catalytic PNP reduction experiments reveal that the synthesized nanocomposite exhibits significantly high catalytic activity with a rate constant of 0.1169 min⁻¹. Moreover, the photocatalytic experiments show that the synthesized nanophotocatalyst has a boosting effect toward MB dye degradation under normal daytime visible light irradiation with a rate constant of 6.38 × 10⁻² min⁻¹. The synergetic effect between silver NPs, PPY and TiO₂ is thought to play a fundamental role in enhancing the photocatalytic activity.

An efficient method to synthesize a magnetic nanocomposite with dual catalytic activities with a synergetic effect between Ag nanoparticles, polypyrrole and TiO₂ is described.     

A novel n-type CdS nanorods/p-type LaFeO3 heterojunction nanocomposite with enhanced visible-light photocatalytic performance

In this work, a novel n-type CdS nanorods/p-type LaFeO₃ (CdS NRs/LFO) nanocomposite was prepared, for the first time, via a facile solvothermal method. The as-prepared n-CdS NRs/p-LFO nanocomposite was characterized by using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), UV-visible diffuse reflection spectroscopy (DRS), vibrating sample magnetometry (VSM), photoluminescence (PL) spectroscopy, and Brunauer–Emmett–Teller (BET) surface area analysis. All data revealed the attachment of the LFO nanoparticle on the surface of CdS NRs. This novel nanocomposite was applied as a novel visible light photocatalyst for the degradation of methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) dyes under visible-light irradiation. Under optimized conditions, the degradation efficiency was 97.5% for MB, 80% for RhB and 85% for MO in the presence of H₂O₂ and over CdS NRs/LFO nanocomposite. The photocatalytic activity of CdS NRs/LFO was almost 16 and 8 times as high as those of the pristine CdS NRs and pure LFO, respectively. The photocatalytic activity was enhanced mainly due to the high efficiency in separation of electron–hole pairs induced by the remarkable synergistic effects of CdS and LFO semiconductors. After the photocatalytic reaction, the nanocomposite can be easily separated from the reaction solution and reused several times without loss of its photocatalytic activity. Trapping experiments indicated that ·OH radicals were the main reactive species for dye degradation in the present photocatalytic system. On the basis of the experimental results and estimated energy band positions, the mechanism for the enhanced photocatalytic activity was proposed.

A novel n–p CdS nanorods/LaFeO₃ (CdS NRs/LFO) heterojunction nanocomposite was prepared via a solvothermal route and applied as a visible-light photocatalyst for enhanced degradation of organic dye pollutants.