Visible Light Photocatalytic Activity Research Articles

Ni2O3-modified SrTiO3 for enhanced visible-light photocatalytic CO2 reduction activity

Low-cost and effective cocatalyst Ni2O3 was loaded on SrTiO3 (STO) via a simple one-step hydrothermal method. The Ni2O3 / SrTiO3 ( m ) photocatalysts were systematically characterized and applied to visible-light-driven CO2 reduction to investigate their photocatalytic activity. The series of the Ni2O3-modified SrTiO3 photocatalysts presented an improved photocatalytic activity and stability. Here, the N5.4STO ( m ) catalyst showed the best photocatalytic activity, with CO and CH4 yielding up to 11.57 and 1.51 μmol / g, respectively, under visible-light irradiation of 3 h, which were 3.15 and 14.84 times higher than that of pure STO(m), respectively. Based on the characterization and experimental results, the enhanced photocatalytic activity might be attributed to the following reasons: (1) Ni2O3 well dispersed on SrTiO3 served as CO2 attachment sites; (2) the modification of Ni2O3 could red shift the absorption edge and broaden the visible-light response ability; and (3) Ni2O3 nanoparticles act as electron traps to capture photogenerated electrons, effectively blocking the recombination of electron–hole pairs. The work offers important insights into the design of non-noble metal oxide cocatalyst modified photocatalysts for electron capture and photoreduction.

A fast and moderate solvothermal method for Bi60In2O93 microspheres: Synthesis, characterization and photocatalytic properties

A visible-light response Bi60In2O93 microsphere was synthesized via a facile solvothermal reaction for photocataytic degradation of organic pollutants. Bi60In2O93 displays an excellent visible-light photocatalytic activity. Experimental results reveal that the morphology of Bi60In2O93 microspheres is largely dependent on the reaction condition of the amount of In(NO3)3·4.5H2O and temperature. The photocatalytic activity of Bi60In2O93 was probed by the degradation efficiency of tetracycline. The degradation efficiency of tetracycline reaches 82.1 % within 1 h under the visible-light irradiation with the assistance of Bi60In2O93. The remarkable photocatalytic performance on Bi60In2O93 microsphere was attributed to efficient electron-hole separation. The reactive species trapping experiment results indicated that the h+ and •O2– are the major active species of the degradation of tetracycline.

Z-scheme heterojunction ZnS/WO3 composite: Photocatalytic reduction of uranium and band gap regulation mechanism

In the present research, ZnS/WO3 composites were prepared by coprecipitation method to construct the Z-scheme heterojunction photocatalyst with high efficiency electron separation for the photocatalytic reduction of U(VI). Compared with WO3 and ZnS, the visible light absorption, photoreduction ability and photocatalytic activity of ZnS/WO3 composites were improved. The ZnS/WO3 composites show higher photoreduction U(VI) performance under visible light irradiation with the maximum extraction capacity of U(VI) at 1.52 g g−1. The ZnS/WO3 composites exhibit high uranium reduction ability under natural light with removal efficiency reaching 93.4 %. In-situ monitoring experiments and DFT calculations were designed to explore the mechanism and pathway of photoelectron transfer in the reduction process from U(VI) to U(IV). The results show that ZnS/WO3 has an internal electric field to form a Z-scheme electron transfer, and uranium reduction is a dual-electron transfer pathway. In addition, the band gap regulation mechanism of binary composite semiconductor materials is deeply discussed.

Green and reusable Ag/AgCl-TiO2 nanocomposites for visible light-triggered dye degradation

• Ag/AgCl-TiO 2 nanocomposites are synthesized in a green, single-step process. • Satureja khuzistanica extract acts as a reducing agent and nanocomposite stabilizer. • More than 99% methyl orange is degraded under visible light irradiation. • High-efficiency TiO 2 -based photocatalysts developed for engineering and environmental applications. Ag/AgCl-TiO 2 plasmonic nanocomposites (NCs) are endowed with excellent visible-light photocatalytic activity. However, only a few studies investigated environmentally friendly approaches to their synthesis. In this work, Ag/AgCl-TiO 2 NCs at five different compositions were prepared in a single-step process by a green and cost-effective route, using Satureja khuzistanica Jamzad aqueous extract. The role of the aqueous plant extract as a reducing and stabilizing agent, and the formation of the NCs were evidenced by several techniques, including FT-IR, EDS, SEM, HRTEM, elemental mapping, and XRD. The morphological analysis demonstrated that the NCs formed nanoaggregates with an average size of 30 nm. The synthesized Ag/AgCl-TiO 2 NCs displayed a remarkable photoactivity in the visible light region, as confirmed by the significantly higher degradation rates of methyl orange (MO) compared to TiO 2 . In particular, the 15% Ag/TiO 2 molar ratio sample revealed a MO degradation efficiency higher than 99% under visible light, and retained high photocatalytic activity even after several degradations runs. Overall, the green, cost-effective, and scalable synthesis of Ag/AgCl-TiO 2 NCs herein reported provides a novel, more sustainable strategy for the high-efficiency modification of TiO 2 photocatalyst in engineering and other environmental applications.

A Study of the Degradation of LEV by Transparent PVA/NCD-TiO2 Nanocomposite Films with Enhanced Visible-Light Photocatalytic Activity

In recent years, antibiotics (such as levofloxacin (LEV)) have been detected widely in the environment. Semiconductor photocatalysis has been recognized as a promising technology for removing pollutants in the environment. In this work, nitrogen and carbon codoped titanium dioxide nano-catalyst (NCD-TiO2) was immobilized in polyvinyl alcohol (PVA) matrix to form PVA/NCD-TiO2 films through solution casting and thermal treatment, which exhibited good photocatalytic efficiency for LEV degradation. The results showed that about 42% LEV can be degraded after 2 h in the presence of PVA/NCD-TiO2 nanocomposite film (the weight ratio of NCD-TiO2 to PVA is 8% and thermal treatment is 120 °C) under visible light. Moreover, possible pathways of photocatalytic degradation of LEV according to the detected intermediates are proposed, which provide insight into the degradation mechanism of LEV by using PVA/NCD-TiO2 photocatalytic films. Finally, the synthesized PVA/NCD-TiO2 films exhibited excellent reusability and stability in photocatalysis. This work provides fundamental support for the design of a high-stability, excellent photocatalyst for practical application.

Hydrothermal synthesis of chalcostibite nanoflowers with enhanced visible light photocatalytic activity

A novel visible-light-driven CuSbS2 nanoflowers (CAS-NFs) catalysts were successfully synthesized through a low-cost and easy hydrothermal method. The unique point of our work is to investigate the photocatalytic activities of the synthesized catalysts and their use for environmental remediation. The as-synthesized CuSbS2 catalysts were carefully characterized by scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, and diffuse reflectance spectroscopy tools. Stoichiometric CAS-NFs were achieved for hydrothermal reaction temperature 150 °C and reaction time closer to 15 h. To check the photocatalytic activity of CAS-NFs, we have used two wastewater dyes, namely, methyl orange and rhodamine B under visible light irradiation. The results indicate that rhodamine B presented higher photocatalytic degradation as compared to methyl orange. Furthermore, the photodegradation rate over five sequential cycles as well as scavenging studies has been scrutinized for RhB dye under visible light. The results indicate its outstanding stability and reusability. Based on the results of radical’s scavenger experiments, we demonstrate that h+ and (•OH) radicals are the main reactive species. Lastly, a judicious mechanism was suggested to demonstrate the photocatalytic degradation process by the CAS-NFs for rhodamine B dye under Xe-lamp irradiation.

Sunlight active TiO2-Bi2WO6 photocatalyst pretreatment of biomass for simultaneous hydrolysis and saccharification in bioethanol production

In this work we examine photocatalysis as an alternative to the conventional enzymatic hydrolysis and liquefaction in the upstream processing of biomass for bioethanol production. A highly efficient visible light active TiO2-Bi2WO6photocatalyst having a band gap of 2.7 eV was used to deconstruct potato mash and casuarina sawdust. Thebiomass was pretreated with thephotocatalyst under sunlight for 5 h and thesawdust was subjected toprolonged treatmentsunder a 65 W fluorescent light source. Photocatalytically deconstructed biomass was subjected to fermentation by yeast. Control biomass was subjected to standard liquefaction byα amylasefollowed by yeast fermentation. Analysis of photocatalytic deconstructed products by ESI-MS reveals increasing glucose accumulation up to two hours followed by decrease upon prolonged pretreatment, suggesting possible cleavageof evolving glucose moieties. Increased concentration of lower carbonfragments in the products further corroborates this finding. HPLC analysis of fermentation products show ethanol yield on samples subjected to photocatalysis as upstream processing is comparable to that of standard enzymatic fermentation. It is thus demonstrated that visible light active photocatalysis of biomass upstream of the fermentation process can be used in place of enzymatic or chemical hydrolysis inethanol production which also constitute an environmentally benign approach.

Nano particle/microsphere TiO2/BiOBr Z-scheme heterojunction with high visible-light photocatalytic activity in tetracycline hydrochloride degradation

Nano particle/microsphere TiO2/BiOBr Z-scheme heterojunction with high visible-light photocatalytic activity in tetracycline hydrochloride degradation

Flexible PAN-Bi2O2CO3–BiOI heterojunction nanofiber and the photocatalytic degradation property

In this paper, one-dimensional PAN-Bi2O2CO3–BiOI photocatalytic nanofibers were prepared using flexible PAN nanofibers as carriers. Bi2O2CO3 was first grown on the surface of PAN nanofibers, and then BiOI was loaded on Bi2O2CO3 by ion exchange method. The characterization results showed that PAN-Bi2O2CO3–BiOI nanofibers have a diameter of about 210 nm and regular fiber morphology. The results of UV–Vis diffuse reflectance spectroscopy, XRD and XPS showed that Bi2O2CO3–BiOI composed of granular semiconductor nano heterostructures with high specific surface area were uniformly loaded on the surface of PAN fiber. The photocatalytic degradation experiment of the material showed high visible light photocatalytic activity. The preparation of Bi2O2CO3–BiOI heterojunction improved the photoelectron hole separation efficiency of BiOI under visible light. PAN-Bi2O2CO3–BiOI fibers showed high photocatalytic degradation efficiency for rhodamine B. The degradation efficiency was more than 95% within 120 min irradiation. Free radical trapping experiments showed photocatalysts mainly produced O2−,·OH and h+, which played a major role in photocatalysis.

Enhanced visible-light photocatalytic activity with Fe2O3–ZnO@C/g-C3N4 heterojunction: Characterization, kinetics, and mechanisms

Heterojunction photocatalysts Fe2O3–ZnO@C/g-C3N4 (FZCCN) were prepared by precipitation and calcination in this study. Systematic characterization demonstrated that the tight interfacial contact was established between Fe2O3–ZnO@C and g-C3N4, and the FZCCN-4 (theoretical mass ratios of ZnO and g-C3N4 was 4) had large BET surface area (110.136 m2 g−1). Bisphenol A (BPA) was selected to estimate the photocatalytic properties of FZCCN and the degradation reaction kinetics was analyzed at the same time. The results showed that, FZCCN-4 had the highest removal rate of BPA (100%, 60 min). The degradation rate of BPA by using FZCCN-4 was approximately 32 and 130 times higher than that of g-C3N4 and Fe2O3–ZnO@C, respectively. ·O2− was proved to be the main active species by capture experiment and electron spin resonance. The UV–vis and PL results proved the formation of heterojunction in FZCCN. This study also identified the intermediates of BPA degradation and tested their toxicity. The excellent visible light catalytic performance of Fe2O3–ZnO@C/g-C3N4 makes it an ideal material for degrading contaminants.

Carbonitrides-modified silver phosphotungstate photocatalysts constructed by thermal post-treatment of self-assembled polyoxometalate hybrids for efficient visible-light photocatalytic activity

Carbonitrides-modified silver phosphotungstate (CN-AgPW) photocatalysts were synthesized by self-assembly and solid-phase thermal polymerization. The microstructural and optical properties of the synthesized photocatalysts were systematically investigated, and the photocatalytic activity was evaluated by the degradation of Aflatoxin B1 (AFB1) under visible light (λ ≥ 420 nm) irradiation. The synthesis process, the interaction of compounds, and Z-scheme charge transfer path of the synthesized photocatalysts were investigated. The rate constants k of CN-AgPW-5 are 12.95 and 12.50 times higher than those of CN-390 and AgPW-390, respectively. This study provides a new strategy for the synthesis and enhancement of photocatalytic efficiency of insoluble polyoxometalate photocatalysts.

Application of visible light active photocatalysis for water contaminants: A review.

Organic water pollutants are ubiquitous in the natural environment arising from domestic products as well as current and legacy industrial processes. Many of these organic water pollutants are recalcitrant and only partially degraded using conventional water and wastewater treatment processes. In recent decades, visible light active photocatalyst has gained attention as a non-conventional alternative for the removal of organic pollutants during water treatment, including industrial wastewater and drinking water treatment. This paper reviews the current state of research on the use of visible light active photocatalysts, their modified methods, efficacy, and pilot-scale applications for the degradation of organic pollutants in water supplies and waste streams. Initially, the general mechanism of the visible light active photocatalyst is evaluated, followed by an overview of the major synthesis techniques. Because few of these photocatalysts are commercialized, particular attention was given to summarizing the different types of visible light active photocatalysts developed to the pilot-scale stage for practical application and commercialization. The organic pollutant degradation ability of these visible light active photocatalysts was found to be considerable and in many cases comparable with existing and commercially available advanced oxidation processes. Finally, this review concludes with a summary of current achievements and challenges as well as possible directions for further research. PRACTITIONER POINTS: Visible light active photocatalysis is a promising advanced oxidation process (AOP) for the reduction of organic water pollutants. Various mechanisms of photocatalysis using visible light active materials are identified and discussed. Many recent photocatalysts are synthesized from renewable materials that are more sustainable for applications in the 21st century. Only a small number of pilot-scale applications exist and these are outlined in this review.

Surface modification of Cu2O-CuO photocatalyst on Cu wire through decorating with TiO2 nanoparticles for enhanced visible light photocatalytic activity

In this paper, the fabrication of Cu2O-CuO/TiO2 nanocomposite photocatalysts on Cu wire was performed successfully via chemical-thermal oxidation and sol-gel process. The chemical-thermal oxidations were applied for Cu2O-CuO nanostructure fabrication on the Cu wire surface. The sol-gel process was utilized for TiO2 nanoparticles decoration as a surface modification process for photocatalytic activity improvement. The X-ray diffraction analysis (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) showed the coexistence of multiple components including Cu2O, CuO, Cu, and TiO2 in the nanocomposite. Field emission electron scanning microscopy (FESEM) results demonstrated remarkable changes in morphology by applying different preparation conditions. The calculated band gap energies from UV–vis diffuse reflectance spectra (DRS) were in the range of 1.72–1.96 eV demonstrating their activity under visible light illumination. Photoluminescence (PL) data indicated delayed recombination of electrons - holes with surface modification due to the formation of heterostructure in the nanocomposite. The investigation of the photocatalytic performance was performed by methylene blue (MB) and methylene orange (MO) dye degradation under visible light illumination and 87 % degradation efficiency was obtained after 120 min. The active species trapping tests involving scavengers demonstrated that the superoxide radicals and holes play more noticeable roles compared to hydroxyl radicals in photocatalytic degradation. The ability to easily separate photocatalyst wires from aqueous solution along with good stability after several cycles of use in degradation is a unique feature of the prepared photocatalysts.

Synthesis and characterization of Ni-doped TiO2 activated carbon nanocomposite for the photocatalytic degradation of anthracene

Nickel-doped titanium dioxide nanoparticles (NDT) deposited on pine cone activated carbon (PAC) have been successfully synthesized by a hydrothermal method. The as synthesized nanocomposite was characterized by X-ray diffraction pattern (XRD), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron (XPS), Fourier transform infrared (FT-IR), UV–visible diffuse reflectance spectra (UV–vis DRS), Photoluminescence (PL), BET surface area, and pHzpc. The characterization results of the prepared nanocomposite revealed that Ni-TiO2 was loaded on the surface of PAC, and had a higher surface area and narrower bandgap than TiO2 nanoparticles. The visible-light photocatalytic activity of the Ni-TiO2@C nanocomposite towards anthracene degradation was found to be 99.9% in 50 mins leading to end products of (1E, 3Z)-hexa-1,3,5-trien-1-ol (1a; m/z = 96), and (1E, 3E)-penta-1,3-dien-1-ol. The synthesized Ni-TiO2@C nanocomposite exhibited a better photocatalytic activity towards the photocatalytic degradation of anthracene as compared to the TiO2 nanomaterial (22.5%) and TiO2/activated carbon nanocomposite (31%) under similar conditions. The photodegradation of anthracene followed the pseudo first-order rate kinetics. The Ni-TiO2@C nanocomposite had excellent regeneration properties till the fifth cycle of use during which it degraded around 73% anthracene.

Reusable catalysts based on CeO2/cellulose derivative with visible light photocatalytic activity tuned by noble metal nanoparticles inclusion

For environmental preservation, it is crucial to effectively remove organic waste from water. Several approaches have been put forth, but photocatalysis stands out as a quick and effective solution. In this study, some hybrid polymeric structures that were created by photopolymerizing cellulose acetate/castor oil urethane methacrylates with embedded CeO2 nanoparticles (NPs) and in situ photogenerated noble metal nanoparticles (Ag, Au, Pd) are characterized, and photochemically thoroughly evaluated. The effective modification of cellulose acetate with urethane methacrylate sequences and the degree of functionalization were first observed using 1H NMR and FTIR spectra. Additionally, scanning and transmission electron microscopy, X-ray diffraction, FT-IR and UV–visible spectroscopy were utilized to analyse the resultant nanocomposites. The homogeneous dispersion of CeO2 NPs (10–40 nm) into an organic matrix with the suitable functionalities, namely urethane and hydroxyl groups, favour the interfacial charge transfer reducing the Eg up to 2.85 eV. Moreover, noble metal nanoparticles (5–15 nm), such as Ag, Au and Pd introduction in nanocomposites, significantly lowered the Eg: 2.1 eV for CeAg samples, 1.7 eV for CeAu films and 1.5 eV for CePd films, respectively. This opens up new avenues for the creation of flexible cellulose-based photocatalysts that are active in visible light.

Two-dimensional photocatalyst with highly efficient and stable visible light photocatalytic activity

Hex ammonium molybdate (AHM), ammonium nitrate (NH4NO3), and glycine were used as the precursors in a microwave-assisted solution combustion synthesis (WSCS) process to create foam-like MoO2 nanoparticles. Methodically investigated was the effect of the glycine/NH4NO3 ratio (=0.25, 0.50, 0.75, 1.0 and 1.25) on the finished goods. The findings indicate that the final morphologies and phases of the products are virtually influenced by the value of Φ. MoO2 nanoparticles measuring 20 to 30 nm can be successfully composited under the condition of Φ=0.50 to produce a foam-like result. The photocatalytic activity of foam-like MoO2 nanoparticles was tested with several pollutants. The results show that foam-like MoO2 nanoparticles have good degradability and stability. The photocatalytic mechanism and fabrication mechanism of foam-like MoO2 has been presented in detail. Using foam-like MoO2-based photocatalyst materials for energy transfer and environment protection is supported by this research.

Two-dimensional photocatalyst with highly efficient and stable visible light photocatalytic activity

Hex ammonium molybdate (AHM), ammonium nitrate (NH4NO3), and glycine were used as the precursors in a microwave-assisted solution combustion synthesis (WSCS) process to create foam-like MoO2 nanoparticles. Methodically investigated was the effect of the glycine/NH4NO3 ratio (=0.25, 0.50, 0.75, 1.0 and 1.25) on the finished goods. The findings indicate that the final morphologies and phases of the products are virtually influenced by the value of Φ. MoO2 nanoparticles measuring 20 to 30 nm can be successfully composited under the condition of Φ=0.50 to produce a foam-like result. The photocatalytic activity of foam-like MoO2 nanoparticles was tested with several pollutants. The results show that foam-like MoO2 nanoparticles have good degradability and stability. The photocatalytic mechanism and fabrication mechanism of foam-like MoO2 has been presented in detail. Using foam-like MoO2-based photocatalyst materials for energy transfer and environment protection is supported by this research.

Carbon-modified TiO2 nanourchin with Ag nanoparticle decoration for environmental remediation

Multifunctional critical nano-composite material assembling Carbon-modified Ag@TiO2 nanourchin was synthesized to investigate visible light photocatalytic activity. The Carbon-modified Ag@TiO2 nanourchin was prepared by a facile two-step chemical synthesis through solvothermal and chemical reduction. Carbon nanospheres as the substrate play a key role for three dimensional nanourchin structure as well as carbon doping. The morphology, crystal structure, and chemical states were characterized carefully by different analytical procedures via transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), RAMAN spectroscopy, X-ray photoelectron spectroscopy (XPS) and UV–Vis spectroscopy. It shows that the uniform loaded silver (Ag) on TiO2 surface was metallic Ag0 state. The exist of interstitial carbon and Ag NPs on TiO2 nanostructure collectively enhance the visible light photocatalytic activity. The visible light photocatalytic degradation of methyl orange (MO) studies revealed that Ag@C0.1TiO2 exhibited enhanced photocatalytic efficiency compared with the pure TiO2 nanourchin and commercial TiO2 powder. The improved photocatalytic property can be attributed to lower recombination of the photogenerated e− and h+ pairs in catalyst due to the formation of a Schottky barrier between Ag NPs and TiO2 which improved the surface charge separation greatly and presence of carbon serve as a sensitizer to absorb visible light which inject e- into conduction band (CB) of TiO2.

Coral-like ZnO/BiOBr Z-scheme heterojunction with excellent visible-light photocatalytic activity

Coral-like ZnO/BiOBr Z-scheme heterojunction with excellent visible-light photocatalytic activity

Efficient Visible-Light Activities of TiO2 decorated and Cr3+incorporated-porous SmFeO3 for CO2 conversion and 4-chlorophenol degradation

In this novel research work, Cr3+ incorporated and TiO2-modified porous SmFeO3-based nanocomposites are prepared via utilizing carbon nanosphere (CNS) as a hard template. Our experimental results proved that the introduction of porosity by employing a sequential template approach (STA) has upgraded the performances of SmFeO3 nanoparticles. Remarkably, the incorporation of Cr3+ increased the light absorption capability by generating surface states and regulating band gap positions, whereas the fabrication of TiO2 enlarged surface area and enhanced charge separation by modulating high-level energy electrons (HLEEs). According to our experimental techniques, including TEM, HRTEM, SEM, TGA, BET, PEC, FS, and PL, it is demonstrated that most optimal 6Cr-PSFO and 4TiO2/6Cr-PSFO nanocomposites have high porosity, appropriate bandgap positions, large surface area, and show superior visible-light photocatalytic activities compared to pristine SmFeO3 nanoparticles. Compared to pristine SFO, the activities of most active 4TiO2/6Cr-PSFO nanocomposites are improved by 8-fold for CO2 conversion and 3-times for 4-chlorophenol (4-CP) degradation. The radical trapping experiment confirmed that the ·OH i are the most active species and has a vital role in the photocatalytic degradation of 4-CP. Moreover, our experimental results are verified and consistent with theoretical calculations and computational studies. Finally, our research work will open up a new gateway for the designing of novel porous SmFeO3-based nanocomposites and their use in CO2 conversion and pollutant removal.