UV Vis Diffuse Reflectance Spectra Research Articles

Fabrication of 1D/2D Y-doped CeO2/ZnIn2S4 S-scheme photocatalyst for enhanced photocatalytic H2 evolution

The construction of well-defined heterojunction structure is considered to be an effective way to improve the efficiency of photocatalytic hydrogen evolution. One-dimensional(1D) Y-doped CeO2 nanorods/two-dimensional (2D) ZnIn2S4 S-scheme heterojunction composite was prepared via hydrothermal and solvothermal method. When the mass ratio of Y-doped CeO2 to ZnIn2S4 is 10 %, the composite exhibits the highest hydrogen evolution rate of 857 μmol·g−1·h−1 under visible light irradiation, which is obviously better than pure Y-doped CeO2 and ZnIn2S4 respectively. Meanwhile, transient photocurrent spectra, photoluminescence (PL) spectra and electrochemical impedance spectroscopy（EIS）measurement indicate that the separation efficiency of photogenerated electrons and holes in the composites is higher. Finally, the S-scheme heterojunction mechanism is determined through UV–vis diffuse reflectance spectra (DRS), VB-XPS spectrum, electron spin resonance (ESR) spectra, ultraviolet photoelectron spectroscopy (UPS) spectra and energy band structure analysis. This study may provide an effective S-scheme heterojunction photocatalysts for photocatalytic hydrogen evolution applications.

Synthesis, characterization, and thermoluminescence‐based high‐dose neutron and gamma dosimetry study of Al5BO9: Mn, Li nanophosphor

AbstractA near tissue equivalent (Zeff = 10.8) and wide bandgap (Eg = 5.95 eV) Al5BO9: Mn, Li nanophosphor was synthesized by facile gel‐combustion (GC) method, and structural characterizations were performed by XRD, infra‐red, transmission electron microscopy, energy‐dispersive spectra, diffuse reflectance UV–visible spectra, and PL studies. Thermoluminescence (TL) study of Al5BO9: Mn, Li revealed the dosimetry glow peak at 542 K, which was absent in undoped Al5BO9 indicating the importance of Mn dopant. The highest TL response was obtained for the lowest studied dopant concentration (0.1 mol% Mn) that was attributed to the concentration quenching phenomenon. The material is highly reusable with low fading (<10%) up to 110 days. TL response for both thermal neutron and gamma radiations showed excellent linearity within 5 × 109–3 × 1011 n/cm2 and 30–5000 Gy, respectively. These studies suggested promising potential of Al5BO9: Mn, Li nanophosphor in clinical neutron dosimetry and food irradiation dosimetry applications. Based on the variation of calcination temperature, strategy toward dual application, namely, radiation dosimeter and red‐light emitting phosphor of the material was established. For a better understanding of the TL process, various kinetic parameters like activation energy (E), order of kinetics (b), and frequency factor (s) were evaluated using different methodologies, and the results were found to be in good agreement.

Interfacial optimization of oxygen-vacancy-induced 1D/2D CeO2 nanotubes/g-C3N4 step-scheme heterojunction with enhanced visible-light photocatalysis and mechanism insight

Oxygen-vacancy-induced one-dimensional (1D) CeO2 nanotubes (CeNT) has successfully loaded on two-dimensional (2D) graphitic carbon nitride (g-C3N4) by simple methods for investigating the performance of photocatalytic degradation of sewage. The results of characterization analyses have proved that the CeNT are uniformly dispersed on the surface of the g-C3N4 nanosheets. The electron paramagnetic resonance (EPR) spectra signal exhibited the existence of oxygen vacancies in CeNT. Photoluminescence spectra (PL), UV–vis diffuse reflectance spectra (UV–vis DRS) and photoelectrochemical measurements demonstrated that the appropriate amount of CeNT (28 mg) can effectively improve the separation efficiency of photogenerated charge carriers and the photoresponse property of the samples. The rhodamine B (RhB) degradation experiments verify the same results that the photocatalytic degradation efficiency of the samples for RhB increased initially, followed by a decreased, meanwhile the degradation activity didn’t decrease prominently after four circles. Also, the reactive species trapping experiment indicated that the holes (h+) and superoxide radicals (∙O2-) played major role in the photocatalytic reaction. Finally, the enhanced photocatalytic performance can be attributed to the synergistic effects of the oxygen vacancies in CeNT and a new charge transfer mechanisms of Step-scheme heterojunction for electron separation, which could provide a new green solution for photocatalytic sewage treatment.

Highly response and humidity-resistant gas sensor based on polyaniline-functionalized Bi2MoO6 with UV activation

The bismuth molybdate (Bi2MoO6) has shown great application potential in the field of gas sensing owing to its abundant Lewis acid sites, suitable energy band and unique layered structure. In this work, a room temperature, highly response, selectivity and humidity-resistant NH3 gas sensor based on the Bi2MoO6/Polyaniline (BMO/PANI) nanocomposite was successfully developed by an in-situ chemical oxidative polymerization process. The obtained samples were characterized by X-ray diffractometer, UV–vis diffuse reflectance spectra, Transmission electron microscopy, X-ray photoelectron spectroscopy, etc. A series of gas-sensing properties studies were conducted with the assistance of UV light, which indicate that UV light illumination could significantly enhance the response of the prepared BMO/PANI sensor and short recovery time (71s). Additionally, the sensor also demonstrated excellent selectivity, repeatability, long-term stability, and moisture resistance. These outstanding characteristics of the sensor are attributed to the dramatic increase of surface state density upon activation by the UV light and the distinctive heterogeneous interface strengthens the interfacial charge transfer.

AgGaGeSe4: An Infrared Nonlinear Quaternary Selenide with Good Performance

The symmetry of crystals is an extremely important property of crystals. Crystals can be divided into centrosymmetric and non-centrosymmetric crystals. In this paper, an infrared (IR) nonlinear optical (NLO) material AgGaGeSe4 was synthesized. The related performance analysis, nonlinear optical properties, and first-principle calculation of AgGaGeSe4 were also introduced in detail. In the AgGaGeSe4 structure, Ge4+ was replaced with Ga3+ and produced the same number of vacancies at the Ag+ position. The low content of Ge doping kept the original chalcopyrite structure and improved its optical properties such as the band gap. The UV-Vis diffuse reflection spectrum shows that the experimental energy band gap of AgGaGeSe4 is 2.27 eV, which is 0.48 eV larger than that of AgGaSe2 (1.79 eV). From the perspective of charge-transfer engineering strategy, the introduction of Group IV Ge elements into the crystal structure of AgGaSe2 effectively improves its band gap. The second harmonic generation (SHG) effect of AgGaGeSe4 is similar to that of AgGaSe2, and at 1064 nm wavelength, the birefringence of AgGaGeSe4 is 0.03, which is greater than that of AgGaSe2 (∆n = 0.02). The results show that AgGaGeSe4 possessed better optical properties than AgGaSe2, and can been broadly applied as a good infrared NLO material.

An Integrated Study on the Fading Mechanism of Malachite Green Industrial Dye for the Marquisette Curtain in the Studio of Cleansing Fragrance, the Palace Museum (Beijing).

Historical marquisette curtains were composed of lightweight fabrics, woven in an open-mesh and leno-type weave, usually made of silk, and found in Qing imperial buildings. As panel curtains, they were exposed to light, and so underwent fading. This study investigated the manufacturing technology and fading mechanism of dyed marquisette fabric from the Studio of Cleansing Fragrance, the Palace Museum (Beijing). The technological aspects were identified. The types of weave, fiber, and adhesive used to fix the curtain to the wooden frame were identified through microscopic observation and infrared spectroscopy. A color change characterization was performed based on UV-visible diffuse reflectance spectra. The textile colorant was identified as malachite green (MG), and its degradation by light was subsequently studied by dynamic photolysis experiments in a kinetic solution for the rapid exploration of by-products. The main degradation pathways were thus identified and the factors responsible for the induced color changes were discussed. A comparison of the liquid chromatography-mass spectrometry (LC–MS) results of the products derived from the photolysis method as well as of the samples extracted from the object allowed for the identification of the presence of different degradation pathways in the faded and unfaded parts of the textile. A metabolomics analysis was applied to account for the differences in the degradation pathways.

Construction of Z-scheme BiOCl/Bi24O31Br10 hierarchical heterostructures with enhanced photocatalytic activity

A novel Z-scheme BiOCl/Bi24O31Br10 heterojunction with hierarchical structure was firstly fabricated, in which BiOCl nanosheets grew in-situ and vertically on the surface of Bi24O31Br10 nanosheets. The obtained BiOCl/Bi24O31Br10 composites exhibited favorable photocatalytic activity for RhB degradation under simulated sunlight irradiation. Especially, BB-0.3 (mass fraction of Bi24O31Br10, 30%) composite performed the best photocatalytic activity, and its degradation rate constant (k) for RhB was nearly 4.1 and 7.7 times higher than that of pure BiOCl and Bi24O31Br10, respectively. Larger specific surface area, wider photo-response range and efficient separation of photogenerated carriers were the main reasons for improving photocatalytic activity, which could be proved by Brunner-Emmett-Teller (BET) analysis, UV–vis diffuse reflectance spectra (UV–vis DRS), photoluminescence spectra (PL), transient photocurrent response and electrochemical impedance (EIS). Meanwhile, the effects of the catalyst dosage, pollutant concentration, initial solution pH and inorganic ions were discussed. Free radical scavenging experiments and electron spin resonance (ESR) measurement indicated that •O2- and h+ made significant contributions to the photocatalytic degradation of RhB. And recycling tests showed that the BB-0.3 heterojunction had a good stability. The possible photocatalytic mechanism of the Z-scheme heterojunction between BiOCl and Bi24O31Br10 was proposed.

Construction of WO3 nanocubes@Loess for rapid photocatalytic degradation of organics in wastewater under sunlight.

In nowadays, environmental pollution has been greatly improved, but the development of low-cost and environmentally friendly materials are still challenge in the field of water treatment. Herein, a cheap and eco-friendly natural loess particle (LoP) was used for in situ growth of tungsten trioxide nanocubes (WO3NCs) on its surface via a simple one-pot hydrothermal method, which afforded a stable loess-based photocatalyst (WO3NCs@LoP). It was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) analysis, UV-Vis diffuse reflectance spectra (UV-Vis DRS), and X-ray photoelectron spectroscopy (XPS). The photocatalytic performances of WO3NCs@LoP were applied to photodegradation of organics under visible-light illumination. It was found that the removal rate of methylene blue (MB) got to 99% within 20min, which was higher than that of materials, such as pure LoP and WO3NCs. Moreover, the photocatalytic activity of WO3NCs@LoP remained 85% after 9 cycling times, indicating its high stability and reusability. It was suggested that the synergy of the well narrowed band gap and effectual control of e--h+ recombination in WO3NCs@LoP improve its photodegradation efficiency. In summary, using natural minerals (LoP) as carrier, a novel eco-friendly photocatalyst could be explored for photodegradation of organic pollutions in wastewater treatment.

Enhanced Photocatalytic Removal of Hexavalent Chromium over Bi12TiO20/RGO Polyhedral Microstructure Photocatalysts.

A Bi12TiO20/RGO photocatalyst with polyhedron microstructure was fabricated via the template-free hydrothermal method, and the visible-light-induced photocatalytic activity of the prepared Bi12TiO20 was also evaluated by the photocatalytic reduction of heavy metal pollutants. The structures and optical properties of the prepared Bi12TiO20/RGO were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectrum (UV–vis DRS). The effects of the reaction time and mineralizer concentration on the formation of the Bi12TiO20 polyhedral microstructure were analyzed. The enhanced photocatalytic performances of Bi12TiO20/RGO were observed which were ascribed to the combination of the Bi12TiO20 microstructure induced photogenerated charges and the RGO nanostructure as a photogenerated charges carrier. The effect of organic acids, p-hydroxybenzoic acid (PHBA), chloroacetic acid, and citric acid on the Cr(VI) photocatalytic reduction was also discussed. This work provides an insight into the design of the bismuth-based microstructure photocatalyst towards the application for environment purification of heavy metals.

Oxygen vacancy triggering the broad-spectrum photocatalysis of bismuth oxyhalide solid solution for ciprofloxacin removal

The construction of a broad-spectrum photocatalytic system is of great significance for maximizing the utilization of solar energy. Herein, a surface oxygen vacancy triggering high-efficient broad-spectrum BiOCl0.5I0.5 solid solution photocatalyst was successfully fabricated via a one-pot solvothermal process. The UV–vis diffuse reflectance spectra revealed that the introduced oxygen vacancy appears to extend the absorption region of BiOCl0.5I0.5 to a wider wavelength range. Under λ > 580 nm light irradiation for 5 h, nearly 85.6% ciprofloxacin was degraded by BiOCl0.5I0.5 with rich oxygen vacancy, the ciprofloxacin removal efficiency was 3.4 times higher than that with less oxygen vacancy. Moreover, the density functional theory calculations and photoelectrochemical characterizations indicated the excited electrons would preferentially transfer to the new defect level induced by oxygen vacancy, thus greatly reducing the recombination of photogenerated carriers. This work tends to deepen the understanding of defect engineering in steering the construction of broad-spectrum Bi-based solid solution photocatalysts as well as its application in environmental remediation.

Synthesis of Na3Co7(PO4)6 by sol-gel and solid-state methods

A new polycrystalline material Na3Co7(PO4)6 has been synthesized by solid-state (ST) and sol-gel (SG) methods and characterized using powder X-ray diffraction (XRD) to solve the structure, which is found to crystallize in the monoclinic system with a P21/c space group. Scanning electron micrographs showed the particles as aggregates with grain sizes ranging from 8 to 35 ​μm and 1 to 20 ​μm, for Na3Co7(PO4)6-ST and Na3Co7(PO4)6-SG, respectively. Energy-dispersive X-ray Spectroscopy (EDS) confirms the presence of Na, Co, P, O elements and their homogenous distribution in the samples. The X-ray photoelectron spectroscopy (XPS) results indicate that the oxidation states for these elements are Na(I), Co(II/III), P(V) and O(-II). The optical bandgaps of Na3Co7(PO4)6-ST and Na3Co7(PO4)6-SG were estimated to be 1.79 ​eV and 1.78 ​eV, respectively, based on the UV–Vis diffuse reflectance spectra. The ionic conductivity for both samples is found to be 3.7 ​× ​10-4 ​S/cm at 300 oC and 6.53 ​× ​10-2 ​S/cm at 450 oC.

Fabrication of an Efficient N, S Co-Doped WO3 Operated in Wide-Range of Visible-Light for Photoelectrochemical Water Oxidation.

In this work, a highly efficient wide-visible-light-driven photoanode, namely, nitrogen and sulfur co-doped tungsten trioxide (S-N-WO3), was synthesized using tungstic acid (H2WO4) as W source and ammonium sulfide ((NH4)2S), which functioned simultaneously as a sulfur source and as a nitrogen source for the co-doping of nitrogen and sulfur. The EDS and XPS results indicated that the controllable formation of either N-doped WO3 (N-WO3) or S-N-WO3 by changing the nW:n(NH4)2S ratio below or above 1:5. Both N and S contents increased when increasing the nW:n(NH4)2S ratio from 1:0 to 1:15 and thereafter decreased up to 1:25. The UV-visible diffuse reflectance spectra (DRS) of S-N-WO3 exhibited a significant redshift of the absorption edge with new shoulders appearing at 470–650 nm, which became more intense as the nW:n(NH4)2S ratio increased from 1:5 and then decreased up to 1:25, with the maximum at 1:15. The values of nW:n(NH4)2S ratio dependence is consistent with the cases of the S and N contents. This suggests that S and N co-doped into the WO3 lattice are responsible for the considerable redshift in the absorption edge, with a new shoulder appearing at 470–650 nm owing to the intrabandgap formation above the valence band (VB) edge and a dopant energy level below the conduction band (CB) of WO3. Therefore, benefiting from the S and N co-doping, the S-N-WO3 photoanode generated a photoanodic current under visible light irradiation below 580 nm due to the photoelectrochemical (PEC) water oxidation, compared with pure WO3 doing so below 470 nm.

Rb2FeGe3S8 and Cs2FeGe3S8: New layered chalcogenides in A2MIIMIV3Q8 family with antiferromagnetic property

Two new layered chalcogenides Rb2FeGe3S8 and Cs2FeGe3S8 were designed and synthesized in A2MIIMIV3Q8 family. These two isostructural compounds belong to the monoclinic space group P21/c. Their 2D layer structure was composed of [FeS4] tetrahedra and [GeS4] tetrahedra in the ab plane. The UV–vis diffuse reflectance spectra indicated that their optical band gaps are 1.64 ​eV and 1.80 ​eV, respectively. Magnetic properties research show that Rb2FeGe3S8 and Cs2FeGe3S8 have antiferromagnetic properties, and their antiferromagnetic transition temperatures are TN ​= ​10.77 ​K and 8.64 ​K, respectively.

Synthesis ZnO heterostructured nanophotocatalyst simulated solar light irradiation for removal contaminate Carbamazepine in aqueous solution

In this study, zinc oxide nanoparticles (ZnO) were produced in aqueous media to photodegrade harmful carbamazepine compounds (CBZ) in aqueous solution under simulated solar-light using the sol-gel technique with zinc chloride and NaOH as precursors. X-ray diffraction (XRD), FTIR analysis, Field Emission Scanning Electron Microscopy (FE-SEM), and UV–vis diffuse reflectance spectra (UV-vis DRS) were used to analyze the ZnO NPs powder. According to the XRD results, ZnO nanoparticles showed a hexagonal symmetry shape with 13 nm particle size value. The absorption bands of ZnO nanoparticles were identified using FT-IR spectra peaking. The ZnO nanoparticles produced in this work are spherical, as seen in the SEM picture, with a band gap of about 3.6 eV. The prepared Zinc Oxide nanoheterostructured photocatalyst utilized excellent performance in reducing Carbamazepine compound with an efficiency of 90%. This study took into account pH solution, catalyst loading, kinetic studies, TOC removal, regeneration, and reusability. The synthesized ZnO successfully removed the Carbamazepine medicine at pH=4. With an R-square of 0.99855, the produced photocatalyst fits well into the pseudo second order model. The ZnO heterostructured nanophotocatalyst retained its outstanding performance after numerous cycles of usage. For these observations, the Zinc Oxide heterostructured photocatalyst for Carbamazepine reduction is a promising photocatalyst.

Constructing S-scheme heterojunction of octahedral flower-like ZnIn2S4/Bi2WO6 nanocone with enhanced photocatalytic activity

In this study, we fabricated octahedral flower-like ZnIn2S4/Bi2WO6 (ZIS/BWO) composite photocatalysts employing octahedral Bi2WO6 nanocones and sheet ZnIn2S4 by in-situ growth method. The synthesized composites were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and X-ray powder diffraction (XRD), respectively. It can be observed that ZnIn2S4 nanosheets grows from the surface of the Bi2WO6 nanocone to form octahedral flower-like ZIS/BWO nanocone composite photocatalysts. The prepared ZIS/BWO composite photocatalysts are speculated that it conforms to the S-scheme heterojunction by UV–vis diffuse reflectance spectra (UV-DRS) and electrochemical analyses combing with the redox potential of reactive oxygen species. The S-scheme heterojunction of ZIS/BWO composite photocatalysts exhibits good separation and transportation of photogenerated carriers by photocurrent and photoluminescence (PL). In addition, the ZIS/BWO composites with S-scheme heterojunction enhances photocatalytic degradation Rhodamine B (RhB), which still showed good photocatalytic activity (62.4%) after four consecutive cycles of photodegradation experiments. This S-scheme heterojunction of the unique structure will be potential and promising photocatalytic catalysts for environmental purification and energy conversion in the coming years.

Synthesis of γ-Fe2O3/La/Bi2WO6 composites for enhanced visible light-driven photocatalytic degradation of tetracycline hydrochloride.

γ-Fe2O3/La/Bi2WO6 heterojunction composites have been successfully synthesized by simple and convenient hydrothermal method. The photocatalytic activity of the prepared samples was evaluated by the degradation of tetracycline hydrochloride (TCH) solution under simulated visible light irradiation. The results indicated that the removal rate of γ-Fe2O3/La/Bi2WO6 samples was higher than that of pure Bi2WO6 and La/Bi2WO6, among which 5%γ-Fe2O3/La/Bi2WO6 had the highest photocatalytic activity. The removal rate of TCH solution can reach 92.42% in 220min. The as-prepared samples were characterized by scanning electron microscope (SEM), Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), and UV-vis diffuse reflectance spectrum (DRS). The material morphology of γ-Fe2O3/La/Bi2WO6 was nano-flake. γ-Fe2O3/La-doped Bi2WO6 did not damage the crystal phase and structure of Bi2WO6. Through getting insight into the mechanism, γ-Fe2O3/La doping increased the specific surface area of Bi2WO6 and inhibited the recombination of photogenerated electron pairs, thus enhancing the photocatalytic activity. h+ and ·O2- were the main active substances in the photocatalytic degradation of TCH solution by γ-Fe2O3/La/Bi2WO6 photocatalysts. In order to better explain the photocatalytic degradation process of TCH solution by γ-Fe2O3/La/Bi2WO6 photocatalyst, a possible removal mechanism was proposed for the first time. Moreover, γ-Fe2O3/La/Bi2WO6 sample is magnetic and easy to recover. At the same time, the high stability of γ-Fe2O3/La/Bi2WO6 sample can be reused.

Prism-like integrated Bi2WO6with Ag-CuBi2O4 on carbon nanotubes (CNTs) as an efficient and robust S-scheme interfacial charge transfer photocatalyst for the removal of organic pollutants from wastewater.

Photocatalytic hybrid carbon nanotubes (CNTs)-mediated Ag-CuBi2O4/Bi2WO6 photocatalyst was fabricated using a hydrothermal technique to effectively eliminate organic pollutants from wastewater. The as-prepared samples were characterized via Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction patterns (XRD), high-resolution transmission electron microscope (HR-TEM), UV-vis Diffuse Reflectance spectrum (UV-Vis DRS), and photoluminescence (PL) studies. The photocatalytic performance of fabricated pristine and hybrid composites was examined by photo-degradation of toxic dye viz. Rhodamine B (RhB) under visible light. Photo-degradation results revealed that the fabricated Ag-CuBi2O4/CNTs/Bi2WO6 semiconductor photocatalyst followed pseudo-first-order kinetics and displayed a higher photocatalytic rate, which was found to be approximately 3.33 and 2.35 times higher than the pristine CuBi2O4 and Bi2WO6 semiconductor photocatalyst, respectively. Re-cyclic results demonstrated that the formed composite owns excellent stability, even after five consecutive cycles. As per the matched Fermi level of CNTs in between Ag-CuBi2O4 and Bi2WO6, carbon nanotubes severed as electron transfer-bridge, Ag doping on CuBi2O4 surface successfully increased photon absorption all across CuBi2O4 surface. Also, it hindered the assimilation of photoinduced electron-hole pairs. The increased photocatalytic efficiency is contributed to the uniform dispersion of photo-generated electron-hole pairs via the construction of an S-scheme system. ROS trapping and ESR experiments suggested that (∙OH) and (O2-∙) were the main radical species for enhanced photo-degradation of RhB dye. The current investigation, from our perspective, highlights the new insights for the fabrication of practical CNTs-mediated S-scheme-based semiconductor photocatalyst for the resolution of environmental issues based on practical considerations.

Environmentally Benign Synthesis of Copper Benzenetricarboxylic Acid MOF as an Electrocatalyst for Overall Water Splitting and CO2 Reduction

As a class of porous coordination polymers, metal organic frameworks (MOFs) have potential applications in many fields. In this work, a novel synthetic method, without using toxic solvents, has been developed to prepare HKUST-1 MOF nanoparticles from coprecipitation reaction of copper (II) chloride and 1,3,5-benzenetricarboxylic acid (trimesic acid) in distilled water. The synthesized nanoparticles were first characterized by X–ray diffraction (XRD), Fourier–transform infrared spectroscopy (FT–IR), and scanning electron microscopy (SEM). The flat–band potential, conduction band, and valence band edges of HKUST-1 nanoparticles were experimentally determined in alkaline solution, and UV–Vis diffuse reflectance spectra (DRS) analysis showed the band gap energy to be 2.5 eV. Electrochemical working electrodes were prepared by electrophoretic deposition of HKUST-1 on the surface of a stainless steel electrode for electrochemical voltammetry and impedance measurements. For the first time the prepared HKUST-1 nanoparticles were investigated as multifunctional electrocatalysts for both overall water splitting and CO2 reduction in alkaline solution. The Tafel plot was used to show the relationship between the over–potential (η) and the logarithmic current density, revealing the kinetic parameters of the electrochemical reactions. Furthermore, the Tafel slope was determined to be 190 mVdec−1, indicating that the Volmer mechanism with electrochemical desorption of hydrogen acts as the rate–determining step (RDS).

Synthesis, characterization, and photocatalysis of a rare-earth cerium/silver/zinc oxide inorganic nanocomposite

Abstract A cerium/silver/zinc oxide (Ce/Ag/ZnO) inorganic nanocomposite was synthesized through a homogeneous precipitation method. The characterization and photocatalysis procedures were carried out by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflection spectroscopy, and photocatalytic performance. The characteristic absorption peak of ZnO was near 432 cm−1, no absorption was observed peak near 1,083 cm−1 for CeO2 and ZnO, the absorption peak near 721 cm−1 was generated by the vibration of CeO2, and the absorption peak had an obvious blue shift. The XRD results showed a strong interfacial interaction among Ag, CeO2 and ZnO to form a core–shell structure. The SEM image showed that the Ce/Ag/ZnO samples are approximately 25 nm. The XPS spectra showed that the Ce/Ag/ZnO nanocomposite powders were successfully prepared. The UV-Vis diffuse reflection spectra showed that the Ce/Ag/ZnO nanocomposites reduced the band gap and increased the ability of visible light response. The addition of rare earth Ce could inhibit the recombination of ZnO photoelectron pairs and improve the photocatalytic effect. Therefore, Ce/Ag/ZnO exhibited good characteristics of nanocomposite materials and good photocatalytic ability.

High performance magnetic carbonaceous materials as a photo Fenton-like catalyst for organic pollutant removal

Herein, three different catalysts, namely carbon nanosphere (CS), Fe3O4@CS, and Fe3O4@g-C3N4/CS, were synthesized by a facile one-pot hydrothermal carbonization approach. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET) surface area analysis, UV–vis diffuse reflectance spectra (UV-DRS), and FT-IR spectra were conducted to study the chemical and physical properties of the catalysts. Thereafter, the catalysts were used for catalytic degradation of methylene blue (MB) in a visible light Fenton-like process. The catalytic activity for MB degradation shows an order of CS < Fe3O4@CS < Fe3O4@g-C3N4/CS. The catalytic system process using Fe3O4@g-C3N4/CS can effectively remove 99.9% of MB at 30 mg/L. Overall, the Fe3O4@g-C3N4/CS-photo Fenton-like system displays promising performance for the degradation of MB.