Major Active Species Research Articles

Robust visible light active PANI/LaFeO3/CoFe2O4 ternary heterojunction for the photo-degradation and mineralization of pharmaceutical effluent: Clozapine

In this work we report the fabrication of novel magnetic ternary PANI/LaFeO3/CoFe2O4 (PLC) heterojunction through in situ polymerization of aniline. As fabricated photo catalyst has been characterized by using FT-IR, XRD and XPS. The surface as well as internal morphologies has been studied by SEM and TEM. The optical activities have been investigated by UV-Vis and photoluminescence spectroscopy. The synthesized catalysts were used for effective photo degradation of pharmaceutical pollutant clozapine (CZP) under visible light irradiation. In comparison with sole counterpart photo catalysts PANI, LaFeO3 and CoFe2O4, PLC demonstrated superior photo-activity, PLC able to degrade 94.2% of CZP over 120 min photo degradation experiment. The effect of catalysts dosage, pH, SO42-, NO3- and HCO3- ion on the photocatalytic activity has been explored. 37.4% and 78.3% of TOC and COD removal has been achieved for the CZP photo-degradation by PLC. The major active radical species have been identified by performing radical scavenging experiment.

Rational design of a novel C/ZnO/BiOI composite for efficient visible-light-driven photocatalysis

A novel C/ZnO/BiOI composite has been fabricated by a simple hydrothermal and ultrasonic method and characterized by XRD, SEM, TEM and XPS. The photocatalytic activity of C/ZnO/BiOI composite was examined by degradation of Rhodamine B (RhB) under visible light irradiation. Compared with ZnO and C/ZnO, the photocatalytic activity of C/ZnO/BiOI was dramatically enhanced, which was determined to be 95.0%. In addition, the C/ZnO/BiOI possessed a stable and efficient photocatalytic activity after five recycling runs. Mechanism study showed that superoxide anionic radicals (O2−) was the major active species.

Instantaneous Sonophotocatalytic Degradation of Tetracycline over NU-1000@ZnIn2S4 Core-Shell Nanorods as a Robust and Eco-friendly Catalyst.

The universal pollution of diverse water bodies and declined water quality represent very important environmental problems. The development of new and efficient photocatalytic water treatment systems based on the Z-scheme mechanisms can contribute to tackling such problems. This study reports the preparation, full characterization, and detailed sonophotocatalytic activity of a new series of hybrid NU@ZIS nanocomposites, which comprise a p-n heterojunction of 3D Zr(IV) metal-organic framework nanorods (NU-1000) and photoactive ZnIn2S4 (ZIS) nanostars. Among the obtained materials with varying content of ZIS (5, 10, 20, and 30%) on the surface of NU-1000, the NU@ZIS20 nanocomposite revealed an ultrahigh catalytic performance and recyclability in a quick visible-light-induced degradation of the tetracycline antibiotic in water under sonophotocatalytic conditions. Moreover, increased activity of NU@ZIS20 can be ascribed to the formation of a p-n heterojunction between NU-1000 and ZIS, and a synergistic effect of these components, leading to a high level of radical production, facilitating a Z-scheme charge carrier transfer and reducing the recombination of charge carriers. The radical trapping tests revealed that •OH, •O2-, and h+ are the major active species in the sonophotocatalytic degradation of tetracycline. Possible mechanism and mineralization pathways were introduced. Cytotoxicity of NU@ZIS20 and aquatic toxicity of water samples after tetracycline degradation were also assessed, showing good biocompatibility of the catalyst and efficacy of sonophotocatalytic protocols to produce water that does not affect the growth of bacteria. Finally, the obtained nanocomposites and developed photocatalytic processes can represent an interesting approach toward diverse environmental applications in water remediation and the elimination of other types of organic pollutants.

High-efficient removal of organic dyes from model wastewater using Mg(OH)2-MnO2 nanocomposite: Synergistic effects of adsorption, precipitation, and photodegradation

• Hierarchical Mg(OH) 2 -MnO 2 nanocomposite (MMNC) was successfully synthesized. • The MMNC exhibits a breakthrough dye removal capacity. • Different removal mechanisms for different concentrations of dye. • The MMNC exhibits excellent visible light photocatalytic activity. • Synergistic effects of adsorption, precipitation, and photocatalysis for dyes removal. Hierarchical Mg(OH) 2 -MnO 2 nanocomposite (MMNC) was successfully synthesized by a facile water-bath method, and further applied to Congo red (CR) and methyl orange (MO) removal. Batch experiments revealed that the maximum removal capacity of the nanocomposite to CR and MO reached 17,100 and 7300 mg g −1 , respectively. The CR removal mechanism was systemically investigated by FESEM, XRD, EDX and XPS techniques. The results showed that the CR removal proceed mainly through chemisorption on MMNC at low concentration. However, at high concentration, Mg 2+ will release from the nanocomposite and react with CR to form a precipitate (Mg-CR), leading to a huge removal capacity. Moreover, MMNC also exhibits excellent performance for photodegradation of CR under visible light irradiation. The active species trapping experiments revealed holes in MMNC and superoxide radical anions as the major active species responsible for photodegradation of CR. The synergistic effects of adsorption, precipitation, and photodegradation enable higher CR removal efficiency, making Mg(OH) 2 -MnO 2 nanocomposite an ideal material for dyes removal from water samples in both low concentration and scabrous high concentration dye-containing wastewater scenarios.

Etch Characteristics of Copper Thin Films in Inductively Coupled Plasma of Piperidine/Ethanol/Ar Gas Mixture

High density plasma reactive ion etching of copper thin films patterned with SiO2 masks was performed via piperidine/ethanol/Ar gas mixture. The etch characteristics of the copper thin films were examined as functions of the gas concentrations in piperidine/Ar and piperidine/ethanol/Ar mixtures. As the piperidine concentration increased, the etch rates of the copper films decreased whereas the etch selectivities of the copper films to SiO2 mask increased and the etch profiles improved. Optical emission spectroscopy studies showed that the major active species in the plasmas of piperidine/Ar and piperidine/ethanol/Ar were CH and CN, which were responsible for the good etch profiles. Further, X-ray photoelectron spectroscopy revealed the formation of CuCN, copper compounds, and polymer layers. Finally, dry etching of copper thin films was successfully accomplished with the optimized piperidine/ethanol/Ar gas mixture, thereby obtaining good etch profiles with high degrees of anisotropy.

Structural, Magnetic, Optical Properties and Photocatalytic Activity of Nanocrystalline Cobalt Ferrite Prepared by Three Different Methods

Cobalt ferrite (CoFe2O4) is an interesting material due to its rich physical properties. In order to study the influence of synthetic methods on the crystalline and morphological structure, optical and magnetic properties of the CoFe2O4, we synthesized here the CoFe2O4 by three different methods, including the chemical co-precipitation method, sol-gel method, and ceramic method. The resulting powders were characterized by different analyses: XRD, SEM, TEM, BET, FTIR, UV-Vis, PL, XPS, and surface acidity. The characterization results showed a significant variation in the structural, particle size, surface area, and optical properties of pure cobalt ferrite with changing the synthetic method. Both XRD and FTIR analyses confirm the formation of the cubic spinel phase, where the crystallite size changes from 21 to 36 nm. XPS analyses demonstrated the effect of the synthetic method on the cation distribution at the tetrahedral and octahedral sites in the spinel ferrite lattice. The magnetic properties of the prepared samples were studied at room temperature using the vibrating sample magnetometer (VSM) and found to be strongly dependent on the synthetic method and showed either ferromagnetic or super-paramagnetic character. The cobalt ferrite samples showed high photocatalytic activity against Basic Red 18 (BR 18) dye under visible light irradiation. The effects of particle size, surface areas, and morphology on the photocatalytic activity were discussed and the positive holes are suggested to be the major active species of the dye dissociation.

Identification of Active Surface Species in Molten Carbonates Using in situ Raman Spectroscopy

Here we report the results of a study on active surface species of a pristine and modified (Li-Na)2CO3 eutectic using in situ Raman spectroscopy technique. The effects of gas compositions, temperature, time, and alkaline earth have been systematically studied. The species of CO42–, HCO4–, and C2O52– are identified as the three major active species on the surface of (Li-Na)2CO3 eutectic by a combined Raman spectroscopy and theoretical density functional theory calculations. The results further reveal that CO42–, HCO4–, and C2O52– are preferably formed in the presence of O2, H2O, and high CO2 concentration. With the addition of Ba to the pristine (Li-Na)2CO3 eutectic, the Raman CO42–/HCO4– shifts become more pronounced.

MnFe2O4 nanoparticles-decorated graphene nanosheets used as an efficient peroxidase minic enable the electrochemical detection of hydrogen peroxide with a low detection limit

Hydrogen peroxide (H2O2) is a common oxidant and major active oxygen species in organisms. There is a great requirement for the accurate and rapid determination of H2O2 in the fields of environmental analysis, clinical treatment, food safety, pharmaceuticals, etc. The electrochemical method is considered an ideal analytical technology due to its high sensitivity, fast response and low detection limit. Herein, a one-pot solvothermal synthesis method was used to prepare a manganese ferrite/reduced graphene oxide (MnFe2O4/rGO) composite, which was modified on the surface of home-made screen-printed electrodes to construct a new type of electrochemical sensor for the determination of H2O2, subsequently. Cyclic voltammetry and chronoamperometry were used to study the electrocatalytic performance of H2O2 reduction in neutral conditions. The results showed that the sensor had good electrocatalytic activity for the reduction of H2O2. The response time of the sensor is 5 s, and the linear detection range is 0.1 ~ 4.0 mM (R2 = 0.9991) with a low detection limit of 0.528 nM. Such sensor exhibited good long-term stability, and good anti-interfering ability from potential interfering species of glucose, ascorbic acid, dopamine, fructose and uric acid during the determination. This study thus provides a potential method to construct novel type of H2O2 for practical application.

Eight crystalline phases of bismuth vanadate by controllable hydrothermal synthesis exhibiting visible-light-driven photocatalytic activity

• We successfully prepared eight crystalline phases of bismuth vanadate by applying the hydrothermal method. • m -BiVO 4 exhibits the greatest visible-light-driven photocatalytic activity on the CV of a series bismuth vanadate. • In the degradation reaction, O 2 − was the major active species, whereas OH and h + were the minor ones. • E g were 2.0–2.3, 2.1–2.2, 2.1–2.3, 2.1–2.2, 2.3–2.5, 2.6, and 2.2–2.6 eV for eight bismuth vanadate, respectively. By applying the hydrothermal method, we successfully prepared bismuth vanadate in a series of crystalline phases. The characteristics of the samples were identified using various techniques, such as scanning electron microscopy–energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, Fourier-transform infrared spectroscopy, high-resolution X-ray photoelectron spectroscopy, diffuse reflectance ultraviolet–visible (UV–vis) spectroscopy, X-ray diffraction, and Brunauer–Emmett–Teller analysis. Consequently, a BiVO 4 series, including monoclinic BiVO 4 ( m -BiVO 4 ), tetragonal BiVO 4 ( t -BiVO 4 ), BiV 1.025 O 4+X , Bi 4 V 2 O 11 , Bi 14 V 5 O 33 , Bi 12 V 2 O 23 , and Bi 9 VO 16 , were effectively prepared using a simple solution-based hydrothermal method. The powder suspension’s photocatalytic activity and the solution’s crystal violet (CV) concentration were measured through UV–vis spectroscopy. The UV–vis spectra revealed optical band gaps of 2.0–2.3, 2.1–2.2, 2.1–2.3, 2.1–2.2, 2.3–2.5, 2.6, and 2.2–2.6 eV for m -BiVO 4 , t -BiVO 4 , BiV 1.025 O 4+X , Bi 4 V 2 O 11 , Bi 14 V 5 O 33 , Bi 12 V 2 O 23 , and Bi 9 VO 16 , respectively—indicating that they were indirect semiconductors. This study verifies that m -BiVO 4 exhibits the greatest photocatalytic activity and is thus a promising candidate for the use in visible-light–responsive photocatalysts.

Bimetal oxalate‐derived synthesis of laponite‐decorated CoFe2O4 porous nanostructures for activation of peroxymonopersulfate towards degradation of rhodamine B

AbstractBACKGROUNDAdvanced oxidation processes based on sulfate radical have been widely employed for oxidation degradation of organic contaminants. Catalytic activation of peroxymonopersulfate (PMS) with transition metal oxides holds great promise for the generation of sulfate radical. In this work, laponite‐decorated CoFe2O4 porous nanostructures have been prepared through the thermal decomposition of laponite/oxalates, and evaluated as a magnetic catalyst to activate PMS for the oxidation of rhodamine B (RhB).RESULTSThe decoration of porous CoFe2O4 microparticles with laponite was evidenced because of the presence of the vibration mode of SiO (at 1359 cm−1) in Fourier transform infrared spectra and the uniform distribution of Si and Mg elements from elemental mapping images. Decorating with laponite also resulted in an increase in amount of surface hydroxyl oxygen species, which facilitated the formation of CoOH complex for PMS activation. Furthermore, the enhanced activation of PMS with laponite‐decorated CoFe2O4 resulted in a faster removal (98.04%) of RhB as compared to undecorated CoFe2O4 (79.62%) within 56 min. Meanwhile, the rate constant increased from 0.0288 (CoFe2O4) to 0.0679 min−1 (laponite‐decorated CoFe2O4). The degradation rate of RhB progressively increased with reaction temperature and catalyst dosage. Scavenging and electron paramagnetic resonance tests manifested that the sulfate and superoxide radicals served as the major active species for the oxidation of RhB molecules.CONCLUSIONThe above results demonstrated positive effects of laponite on the textural property, surface chemical states and catalytic activity of porous CoFe2O4 microparticles. This study provides an insight into the promising role of laponite as an additive in improving PMS activation.

Synthesis of Bi2WO6/g-C3N4 photocatalyst and high degradation of Rhodamine B under visible light irradiation

PurposeThe purpose of this paper is to improve the degradation efficiency of Rhodamine B (RhB) by new photocatalytic materials.Design/methodology/approachBinary Z-scheme g-C3N4/Bi2WO6 photocatalytic material was synthesized by the one-step hydrothermal reaction. The construction of Z-scheme heterojunction led to the rapid separation of photogenerated electrons and holes, which would degrade RhB into small molecular substances to achieve the purpose of degradation.FindingsIt was found that Bi2WO6/25%g-C3N4 displayed the highest photocatalytic activity, which was about 1.44 and 1.34 times higher than that of pure Bi2WO6 and g-C3N4, respectively. According to the trapping experiments, the superoxide radical (·O2−) was the major active species of the RhB decomposition in Bi2WO6/g-C3N4 catalysts.Originality/valueThe successful synthesis of Z-scheme Bi2WO6/g-C3N4 provides new ideas and references for the design of catalysts with high photocatalytic activity, which should have wide applications in the future.

0D/1D Z-scheme g-C3N4 quantum dot/WO3 composite for efficient Cr (VI) photoreduction under visible light

The appropriate construct of Z-scheme heterostructure composite with high photocatalytic activity has created new opportunities for environmental protection. Herein, graphitic carbon nitride quantum dots/tungsten trioxide (CNQDs/WO 3 ) was firstly fabricated using CNQDs decorated onto the surface of WO 3 nanorod grown along the [110] orientation in hydrothermal environment to construct a Z-scheme heterostructure composite. By various characterization methods, the crystal structure, micro morphology, atomic valence state and surface functional groups of the catalyst were systematically revealed. The results indicated that Z-scheme heterojunctions between CNQDs and WO 3 were successfully constructed. Compared with pure WO 3 , CNQDs/WO 3 exhibited prominent photoreduction performance under visible light irradiation. The optimal 5% CNQDs/WO 3 could reduce almost 100% Cr (VI) under acidic condition with the best photocatalytic activity within 90 min. More than this, 5% CNQDs/WO 3 also displayed excellent stability and recyclability even after five cycles of photoreduction experiments. Based on the free radical quenching experiments, the possible photoreduction reaction mechanism had been proposed in detail. The Z-scheme heterostructure provided the possibility of the generation, rapidly transfer and efficient separation of photogenerated electrons, which were major active species in the Cr (VI) photoreduction process. • 0D/1D Z-scheme heterojunction composite CNQDs/WO 3 has been constructed. • The Z-scheme heterojunction structure improved the separation and transfer of photogenerated electrons efficiently. • CNQDs/WO 3 exhibited excellent activities in Cr (VI) photoreduction.

Palladium Nitrosyl Complexes as Highly Versatile Catalysts for C−H/C−H Oxidative Coupling of Arenes: Application Area and Insight into Mechanism

AbstractPalladium nitrsosyl carboxylates Pd3(NO)2(CX3CO2)4(ArH)2 (I: X=Cl, Ar=Ph; II: X=F, Ar=Tol) are found to be effective catalysts for C−H/C−H oxidative homocoupling of arenes bearing electron‐donor as well as electron‐withdrawing groups (EWG). Trifluoroacetate complex II is found to be more promising due to higher stability under the reaction conditions. Complex II also shows high performance in intramolecular coupling in diarylsulfides, diarylethers and diarylamines giving corresponding dibenzothiophenes, dibenzofurans and carbazoles with yields ranged from moderate to high. The plausible mechanism is studied by DFT computational analysis basing on Pd3 linear complexes as major active species. It was found that two deprotonation steps proceed in two different ways: for the first deprotonation SEAr is most probable pathway while for the second one concerted metalation‐deprotonation (CMD) is preferable. That can explain high tolerance of the system to different substrates: SEAr is favorable in the presence of electron donor group and EWG facilitate CMD. NO group was found to be involved into the CMD pathway and that is the rate‐determining step with the highest activation barrier.

Improved photocatalytic degradation of rhodamine B under visible light and magnetic properties using microwave combustion grown Ni doped copper ferrite spinel nanoparticles

Nanoparticles (NPs) of Cu1-xNixFe2O4 (0 ≤ x ≤ 0.5) have been facilely prepared via combustion through microwave technique. X-ray diffraction outcomes confirmed single-cubic phase synthesis of titled material and mean crystallites size and lattice constants were calculated in range of 19.37–22.69 nm and 8.319–8.248 Å, respectively. The XPS study confirms the chemical elements and oxidations states of Cu0.6Ni0.4Fe2O4 NPs. The high-resolutionSEM study reveals spherical NPs with agglomeration and composition of elements in Cu1-xNixFe2O4 (0 ≤ x ≤ 0.5) was confirmed through EDX study. The Kubelka-Munk model was employed to determine the energy gap of Cu1-xNixFe2O4 NPs and noticed to vary from 2.30 to 2.06 eV. Photoluminescence spectra study explained the rate of recombination of electron and hole pairs. The detailed magnetic study was carried out and magnetization of remanence (Mr), coercivity (Hc) & saturation (Ms) values were estimated through recording the hysteresis plots. The magnetic Mr & Ms values are noticed to be enhanced from 5.21 to 11.02 emu/g &17.37–31.37 emu/g with Ni content. Furthermore, the Cu1-xNixFe2O4 (0 ≤ x ≤ 0.5) NPs were studied by means of visible light induced RhB dye degradation and investigates major active species and a probable mechanism for degradation has been conferred. The photocatalytic activity of CuFe2O4 NPs has been improved via Ni doping. Photoluminescence spectra showed the rate of recombination of electron-hole pairs and presence of defects.

SYNTHESIS OF Cr-DOPED SrMoO4 WITH ENHANCED PHOTOCATALYTIC PERFORMANCE VIA HYDROTHERMAL METHOD

Cr-doped SrMoO4 visible-light-driven photocatalysts were successfully synthesized by one-pot facile hydrothermal technique. The results show that Cr doping slightly affected the crystal structure of SrMoO4. However, Cr doping plays an important role in sample morphology. Photocatalytic properties were evaluated by the degradation of methyl blue under visible-light irradiation. Electron spin resonance measurements show that the •O2  radical is the major active species in photodegradation. Photocatalytic measurement results indicate that Cr3+ doping effectively increases the photocatalytic activity of SrMoO4. When the Cr doping is 7%, the doped SrMoO4 exhibits the best photocatalytic performance. The increase in photocatalytic activity can be attributed to the following two factors: One is the decrease in sample band gap, and the other is the lower recombination ratio of photoinduced electron–hole pairs with Cr doping. The current experimental results clearly indicate that Cr doping is a useful method to improve the photocatalytic properties of SrMoO4 material.

Introducing Ag2O-Ag2CO3/rGO nanoadsorbents for enhancing photocatalytic degradation rate and efficiency of Congo red through surface adsorption

Abstract In order to enhance the stability and engineering of silver-based photocatalysts for solving environmental pollution problems, Ag2O-Ag2CO3 nanoparticles and reduced graphene oxide (rGO) were used to prepare a Ag2O-Ag2CO3/rGO nanocomposite. The results showed that Ag2O-Ag2CO3 nanoparticles were homogeneously distributed over the entire surface of 15 % (w/w) rGO in the composite. Moreover, higher visible light harvesting, faster charge carrier transportation and more appropriate correlation between adsorption and photodegradation processes were achieved. Statistical analysis on both linear and nonlinear isotherms showed that the kinetic and the adsorption process were well described by a pseudo-second-order kinetic model (Qe.cal = 215.0 mg g−1) and a Langmuir isotherm (Qe.cal = 178.0 mg g−1), respectively. Investigation of the photodegradation rate constant of Congo red (CR) revealed that the photocatalytic efficiency of Ag2O-Ag2CO3/rGO (0.1038 min−1) was about 18 times higher than Ag2O-Ag2CO3 (0.0058 min−1). The results also indicated that ˚OH radical and holes might be the major active species for photodegradation of CR. It was concluded that the Ag2O-Ag2CO3/rGO nanocomposite synergistically extended the light absorption and photocarrier diffusion length which is of great concern in environmental pollutants remediation.

Tetracycline degradation by persulfate activated with magnetic γ-Fe2O3/CeO2 catalyst: Performance, activation mechanism and degradation pathway

Abstract Tetracycline is a typical antibiotic that is eco-toxic and easily causes bacterial resistance, and thus it is necessary to eliminate tetracycline from the water environment. In this work, γ-Fe2O3/CeO2 was prepared and used to activate persulfate for tetracycline degradation. The catalyst was characterized by XRD, VSM and XPS, and results showed that it had excellent crystallinity and magnetism. The low valence metals (Fe (II) and Ce (III)) in γ-Fe2O3/CeO2 benefited persulfate activation. Tetracycline removal efficiency reached 84% with the γ-Fe2O3/CeO2/persulfate system; and the value was 70% in the surface water matrix. In addition, γ-Fe2O3/CeO2 kept high activity from pH 3 to 9. It had high stability and reusability and was easily recycled from solution due to its good magnetism. Mechanism analyses showed that SO4 − and OH on catalyst surface catalyst were the major active species, O2 − and 1O2 were also produced due to the excess oxygen vacancies of catalyst. Moreover, the degradation products of tetracycline were determined, and the degradation pathway was proposed. Hydroxylation, demethylation, decarbonylation, dehydroxylation, C-N bond cleavage and ring-opening were the main pathway. The cost of wastewater treatment with the γ-Fe2O3/CeO2/persulfate system was estimated to be 0.106 $/m3. This study provided an efficient and stable catalyst for tetracycline degradation.

Template-free synthesis of high specific surface area gauze-like porous graphitic carbon nitride for efficient photocatalytic degradation of tetracycline hydrochloride

Toxic solvents and chemicals are usually used to prepare carbon nitride. Therefore, a low-toxic template-free method was proposed to prepare gauze-like porous graphitic carbon nitride (CCM18) with high specific surface area. The morphology, crystal and surface structure, specific surface area and optical properties of CCM18 were characterized, and the removal efficiency for tetracycline hydrochloride (TC) degradation under simulated sunlight was evaluated. The results showed that CCM18 has a specific surface area of 107.4 m2 g-1, stronger light absorption capacity and a band gap energy of 2.92 eV. The degradation rate of TC by CCM18 was more than twice that of BCN. The experiment of radical scavengers confirmed that superoxide radicals (O2-) and hydroxyl radical (OH) were the major active species. The enhanced performance of CCM18 for TC degradation (82%) and the stability of CCM18 that can be reused multiple times indicated the prospect of industrial application.

Elucidation of the photocatalytic degradation mechanism of an azo dye under visible light in the presence of cobalt doped TiO2 nanomaterials

In this study, Co-TiO2 nanoparticles were successfully synthesized using sol-gel and precipitation methods. The effect of Co amount on the physicochemical properties of these nanomaterials was investigated using various techniques. The obtained results showed that the structural and optical properties of the synthesized Co-TiO2 nanomaterials depended closely on the weight percent of Co added to TiO2. It was found that, for 1%Co-TiO2, a substitution of Ti4+ and Co2+/Co3+ within the lattice of TiO2 was happened. The results of the photocatalytic degradation of methyl orange (MO) experiments carried out in the presence of the as prepared nanomaterials showed that under visible light, the sample 1%Co-TiO2 exhibited the best MO conversion. The enhanced photocatalytic activity has been attributed to the efficient charge separation of electrons and holes. The mechanistic studies revealed that O2-, h+ and OH are the major active species, and a possible mechanism degradation pathway of MO dye is proposed.

Rational design of novel CrZrOx catalysts for efficient low temperature SCR of NOx

Novel CrZrOx catalysts were designed and synthesized by the co-precipitation method and the first time used for selective catalytic reduction of NOx with NH3 (NH3-SCR). The promotional effect of ZrO2 on Cr2O3 catalysts was investigated. The SCR performance of Cr2O3 was significantly enhanced with the appropriate addition of ZrO2 in CrZrOx, owing to the formation of solid solution structure and Cr-O-Zr conjunction bonds. Among the tested CrZrOx catalysts, the catalyst with Cr:Zr = 1:1 showed the optimal NOx removal efficiency at low temperatures, with the highest NO removal efficiency of 97.5% at 180 °C , excellent SO2 and H2O resistance at 300 °C with 50 ppm SO2 and 5% H2O. It appears that the reaction mechanisms followed the Langmuir-Hinshelwood model and NH3*, NH4+*, monodentate nitrates and nitrites were the major active intermediate species. The structure change modified the surface properties of the CrZrOx catalyst, increasing the concentrations of the acid sites, surface adsorbed oxygen Oa and Cr6+, which were responsible for the enhancement of SCR performance.