Metal Ions Cr Research Articles

Eu3+-anchoring Zirconium-organic framework for enhancing fluorescence sensing detection sensitivity towards Cr(VI) ions

Heavy metal ion Cr(VI) content has been regarded as one of the most important indicators for discharged industrial wastewater. However, effective identification and detection of Cr(VI) analytes with high sensitivity and selectivity from various water environments remains a significant challenge. In this study, a novel luminescent material (labelled as Eu@Zr-MOF) with high water stability was assembled by post-modification of a zirconium-organic framework with lanthanide Eu3+ ions. And the coordination bonds binding between Eu3+ ions and carboxyl O atoms of Zr-MOF were confirmed by XPS technique. After Eu3+ ions were successfully immobilized within the Zr-MOF lattice, Eu@Zr-MOF exhibits a bright red fluorescence signal which was inherited from the unique luminescent feature of embedded Eu3+ ions. Notably, Eu@Zr-MOF can be deployed as a reliable photochemical sensor for quantitative fluorescence quenching detection of Cr2O72− ions based on the emission peak at 618 nm, showing rather high sensitivity (KSV = 6.746 × 104 M−1) and ultra low detection limit (DL = 5.71 ppb) which has been enhanced more than 3 times compared with pristine Zr-MOF. This study provides a reliable reference for the preparation of novel luminescent MOFs platform for efficient recognition and detection of Cr(VI) analytes.

MIL-125(Ti)-derived double vacancy-induced enhanced visible-light-driven TiO2 p-n homojunction for photocatalytic elimination of OFL and Cr(VI)

The efficient removal of quinolone antibiotics and heavy metal ions Cr(VI) using photocatalysis has attracted increasing attention in the field of environmental remediation. Here, we create a porous TiO2 p-n junction featuring titanium vacancies and oxygen vacancies. The double-deficient TiO2 p-n junction has the same catalytic ability as P25 under UV light. Still, it also can produce copious radicals under visible light excitation to achieve oxidative degradation of ofloxacin and reduced Cr (VI). This is helped by the two reaction centers generated by oxygen and titanium vacancies, the effective light-trapping capacity, and the close interfacial contacts. By adjusting the calcination temperature, oxygen vacancy, and titanium vacancy concentrations, TiO2 p-n junctions with the best photocatalytic activity were produced. In the pH range of 3.63–9.65, TiO2 p-n junctions maintained outstanding activity. The degradation pathway of ofloxacin was examined using theoretical calculations and LC-MS. This study provides a technically guided experimental basis for preparing photocatalytic materials with double-defective p-n junctions.

REDUCTION OF METAL ION RELEASE IN CEMENTED HIP STEMS BY A ZIRCONIUM NITRIDE MULTILAYER COATING

ZrN-multilayer coating is clinically well established in total knee arthroplasty [1–3] and has demonstrated significant reduction in polyethylene wear and metal ion release [4,5].The goal of our study was to analyze the biotribological behaviour of the ZrN-multilayer coating on a polished cobalt-chromium cemented hip stem.CoCr28Mo6 alloy hip stems with ZrN-multilayer coating (CoreHip®AS) were tested versus an un-coated version. In a worst-case-scenario the stems with ceramic heads have been tested in bovine serum in a severe cement interface debonding condition under a cyclic load of 3,875 N for 15 million cycles. After 1, 3, 5, 10 & 15 million cycles the surface texture was analysed by scanning-electron-microscopy (SEM) and energy-dispersive x-ray (EDX). Metal ion concentration of Co,Cr,Mo was measured by inductively coupled plasma mass spectroscopy (ICP-MS) after each test interval.Based on SEM/EDX analysis, it has been demonstrated that the ZrN-multilayer coating keeps his integrity over 15 million cycles of severe stem cemented interface debonding without any exposure of the CoCr28Mo6 substrate.The ZrN-multilayer coated polished cobalt-chromium cemented hip stem has shown a reduction of Co & Cr metal ion release by two orders of a magnitude, even under severe stem debonding and high interface micro-motion conditions.ZrN-multilayer coating on polished cobalt-chromium cemented hip stems might be a suitable option for further minimisation of Co & Cr metal ion release in total hip arthroplasty. Clinical evidence has to be proven during the next years.

Simultaneous Determination of Mixed Heavy Metal Ions Cr (III) and Co (II) in Wastewater by Cloud Point Extraction Dual Wavelength Spectrophotometry

Using cloud point extraction technology and the principle of absorbance addition in multi-component system, the mixed metal ions Cr (III) and Co (II) in industrial wastewater were enriched and determined at pH 5.0 and 50℃, using ammonium pyrrolidine dithiocarbamate (APDC) as complexing agent and Triton X-114 as extractant. The results indicate that the contents of Cr (III) and Co (II) can be calculated using a simultaneous equation system. The detection limits for Cr (III) and Co (II) are 0.74 ng/ml and 2.12 ng/ml, respectively. The recovery rates are 95.3% -104.0% and 96.9% -103.5%, respectively. This method has the characteristics of high accuracy, good repeatability, and fast detection speed, and has good practical value.

The effect of cetyltrimethylammonium bromide (CTAB) addition on green synthesis of porous N-doped TiO2 for photoreduction of heavy metal ion Cr(vi).

In this study, porous TiO2 photocatalysts modified by nitrogen (NCT) were successfully synthesized using a combination of green synthesis methods by utilizing Aloe vera (L.) Burm. f. peel and hydrothermal method. In addition, TiO2 was modified by increasing the active surface area using Cetyltrimethylammonium Bromide (CTAB). The X-ray Diffraction (XRD) results indicated that the anatase phase was formed. The result of the Diffuse Reflectance Spectroscopy UV-Vis (DRS UV-Vis) using the Tauc-plot method showed that all porous N-doped TiO2 samples experienced a decrease in the energy gap. This indicates the successful modification of TiO2 by nitrogen, as confirmed by the Fourier Transform Infra-Red (FTIR) result. Field Emission Scanning Electron Microscopy (FESEM) result showed that the synthesized TiO2 had a spherical morphology of 10-30 nm diameter. The Braunauer, Emmett, and Teller (BET) result indicated that the type IV isotherm curve with a mesoporous structure was formed. The NCT0.75 sample had a surface area and pore size of 95.02 m2 g-1 and 8.021 nm, respectively, while the NTi0.75 sample had a surface area and pore size of 90.97 m2 g-1 and 5.161 nm, respectively. The photocatalytic activity of the porous N-doped TiO2 was tested on photoreduction of metal pollutant model Cr(vi). The result demonstrated that the NCT0.75 sample had the most optimal photocatalytic activity by reducing 89.42% of Cr(vi) metal ions.

Simultaneous photocatalytic removal of heavy metal and organic dye over nitrogen and sulfur co-doped hierarchical ZnSnO3/Zn2SnO4 hollow octahedrons

A series of hierarchical N, S co-doped ZnSnO3/Zn2SnO4 porous hollow octahedrons (NS/ZnSnO3/Zn2SnO4) were constructed using the strategy of combining acid-etching technique with in-situ decoration method for the removal of various pollutants in aqueous environment. The optimized NS/ZnSnO3/Zn2SnO4 exhibited an enhanced photocatalytic activity under simulated sunlight, removing heavy metal ion Cr(VI) in 140 min and rhodamine B (RhB) in 50 min, outperforming hollow Zn2SnO4 and ZnSnO3/Zn2SnO4 octahedrons. This raise could be attributed to the synergetic effect of ZnSnO3/Zn2SnO4 heterojunctions, the introduction of N, S elements and unique hierarchical porous hollow morphology. In addition, the photocatalytic activities of NS/ZnSnO3/Zn2SnO4 for removing Cr(VI) and RhB from mixed pollutant solutions were 1.94 and 1.53-folds as high as those of single system, and it also displayed good reusability and stability in co-existing system, suggesting its potential practical applications in the simultaneous removal of various pollutants from contaminated water.

Low-Cost Yet High-Performance Hydrochar Derived from Hydrothermal Carbonization of Duku Peel (<i>Lansium domesticum</i>) for Cr(VI) Removal from Aqueous Solution

Carbon-based adsorbent as a hydrochar (Hc) material with Duku (Lansium domesticum) peel precursors has been successfully synthesized as evidenced by XRD, FT-IR, BET, and SEM analysis. XRD analysis showed the presence of diffraction peaks around 16° and 22° which indicated the presence of carbonaceous material. This is confirmed by FTIR analysis which shows the presence of vibration at 2931 cm−1 of cellulose. SEM data results showed that heterogeneous and has an irregular shape and surface area increased twice from Duku peel to Hc. Duku peel and Hc adsorbent materials were applied to adsorb heavy metal ions Cr(VI). Kinetic parameters of Cr(VI) using Duku peel and Hc showed that the optimum time reached was at 120 min. The adsorption kinetics model of Cr(VI) using Hc tends to follow the PFO model and Langmuir isotherm adsorption. Duku peel material used to adsorb Cr(VI) reached an adsorption capacity of 42.19 mg/g, while in Hc material there was an increase that reached 80.64 mg/g. The thermodynamic parameters of both materials show that the adsorption process is spontaneous.

Bifunctional Sensors Based on Phosphomolybdates for Detection of Inorganic Hexavalent Chromium and Organic Tetracycline.

Exploring effective sensors for detecting possible hazards in a water system are greatly significant. This work proposed a strategy for stable and effective bifunctional sensors via incorporating hourglass-type phosphomolybdates into metal-organic fragments to construct a high-dimensional framework. Two hourglass-type phosphomolybdate-based electrochemical sensors toward heavy metal ion Cr(VI) and tetracycline (TC) detection were designed with the formula [CoII2(H2O)4NaI2][CoII(Hbpe)][NaI(bpe)1.5]{CoII[PV4MoV6O31H6]2}·9H2O (1) and [CoII(H2O)4NaI3][CoII(Hbpe)][CoII(bpe)]{CoII[PV4MoV6O31H6]2}·9H2O (2) [bpe = 1,2-di(4-pyridyl)ethylene]. Structural analysis showed that hybrids 1 and 2 possess three-dimensional POM-supported network features with favorable stability and exhibit reversible redox properties. Experiments found that this kind of hybrids as efficient sensors have excellent electrochemical performance toward Cr(VI) detection with high sensitivities of 0.111 μA·μM-1 for 1 and 0.141 μA·μM-1 for 2, fast response time of 1 s, and low detection limits of 30 nM for 1 and 27 nM for 2, which far meet the standard of WHO for drinking water. Moreover, hybrids 1-2 also exhibit fast responses to TC detection with sensitivities of 0.0073 and 0.022 μA·mM-1 and detection limits of 0.426 and 0.084 mM. This work offers a novel strategy for the purposeful design of efficient POM-based electrochemical sensors for accurate determination of contaminants in a practical water system.

Internal coordination of vanadium industrial waste—Preparation of hydroxyapatite and fluorine wastewater purification

In the vanadium industry, raffinate poses potential environmental risks due to the presence of corrosive fluoride and toxic heavy metals, and waste neutralizing slag (NS) was largely stockpiled given the low economic value, resulting in extensive land occupation and secondary pollution risks. Hydroxyapatite (HAP) was synthesized uniformly from the NS using the hydrothermal method, with no surfactants or additives used except for the three inexpensive reactants required. It was discovered that the pH of the raw material, the temperature, and the length of the hydrothermal reaction all had a significant effect on the adsorption characteristics of the produced HAP. When the conditions for synthesizing HAP were set with a pH of 11.5, a hydrothermal reaction temperature of 120 °C, and a reaction time of 1.5 h, the HAP had the optimum impact on raffinate treatment. The products' characterization by XRD, FTIR, SEM-EDS, and BET corroborated the successful synthesis of homogeneous HAP under the process conditions. The waste stream from the hydrothermal synthesis of HAP was recovered and crystallized to obtain a sodium sulfate by-product which was determined for purity. Adsorbed at room temperature for 1 h, the HAP synthesized by NS has a maximum percentage adsorption of 99.66 % and a saturation adsorption capacity of 43.64 mg/L for F ions in the raffinate. Additionally, the HAP removed over 95 % of the trace heavy metal ions Cr, As, and Cd from the raffinate. The saturated HAP was treated using a hydrothermal regeneration process, and the regenerated HAP retained a fluoride percentage adsorption still reaching 99.28 %. The thermodynamic and leaching experiments reveal that the desorption solution for the regeneration of HAP has the performance to increase the efficiency of vanadium recovery. This technique recycles waste NS to produce high-value HAP, which purification treatment of the raffinate with a high fluorine and contaminants content, solves the problem of treating two types waste of vanadium industry waste (NS and raffinate), and allows for the recycling of valuable element fluorine in vanadium industrial effluent.

Rich Indium-Vacancies In2 S3 with Atomic p-n Homojunction for Boosting Photocatalytic Multifunctional Properties.

Design and development of highly efficient photocatalytic materials are key to employ photocatalytic technology as a sound solution to energy and environment related challenges. This work aims to significantly boost photocatalytic activity through rich indium vacancies (VIn ) In2 S3 with atomic p-n homojunction through a one-pot preparation strategy. Positron annihilation spectroscopy and electron paramagnetic resonance reveal existence of VIn in the prepared photocatalysts. Mott-Schottky plots and surface photovoltage spectra prove rich VIn In2 S3 can form atomic p-n homojunction. It is validated that p-n homojunction can effectively separate carriers combined with photoelectrochemical tests. VIn decreases carrier transport activation energy (CTAE) from 0.64eV of VIn -poor In2 S3 to 0.44eV of VIn -rich In2 S3 . The special structure endows defective In2 S3 with multifunctional photocatalysis properties, i.e., hydrogen production (872.7µmol g-1 h-1 ), degradation of methyl orange (20min, 97%), and reduction in heavy metal ions Cr(VI) (30min, 98%) under simulated sunlight, which outperforms a variety of existing In2 S3 composite catalysts. Therefore, such a compositional strategy and mechanistic study are expected to offer new insights for designing highly efficient photocatalysts through defect engineering.

Fast and efficient removal of dyes and Cr(VI) ion from wastewater using halloysite nanotubes-covalently coated polyurethane sponges

Inspired by the mussel adhesion protein, dopamine was used to prepare polydopamine (PDA)-coated polyurethane sponge (PDA-PUS) via self-polymerization reaction. Halloysite nanotubes (HNTs) were grafted with γ-aminopropyltriethoxysilane (APTES). The new organic-inorganic hybrid adsorption material (HNTs@PUS) was fabricated by covalent link of APTES-grafted HNTs and PDA-PUS through Schiff base reaction/Michael addition. The as-prepared HNTs@PUS showed much higher mechanical stability and compressive property than polyurethane sponge (PUS). HNTs@PUS had 7.7, 7.1, 1.7 and 8.5 times adsorption capacity of PUS for Congo red (CR), Methyl orange (MO), Rhodamine 6 G (R6G) and heavy metal ion Cr(VI), respectively. HNTs@PUS had a fast adsorption rate and most of CR, MO, R6G and Cr(VI) were adsorbed by HNTs@PUS within 20 min. In addition, HNTs@PUS maintained 70.3%, 66.5%, 67.3% and 77.4% of its adsorption capacity for CR, MO, R6G and Cr(VI), respectively, after 5 cycles of regeneration. HNTs@PUS could be easily recovered to avoid secondary contamination. Besides, using HNTs@PUS as adsorbents, a continuous flow adsorption device was developed, through which anionic and cationic dyes and heavy metal ion could be continuously and effectively removed from the flowing solution. These results demonstrated that HNTs@PUS had potentially ideal attributes for use as adsorbents in the ultrafast, high efficiency and large-scale removal of anionic and cationic dyes and heavy metal ions from wastewaters. The fabrication strategy not only solved the problem of the poor recyclability and low permeability of HNTs, but also greatly improved the adsorption capacity of PUS, which might accelerate the application of natural “green” HNTs in wastewater treatment.

New Metal Complexes Derived from Heterocyclic Schiff-base Ligand; Preparation, Structural Investigation and Biological Activity

The formation of a Schiff-base with N2O2 donor atoms derived from the hydrazine segment and its metal complexes are reported. The Schiff-base ligand; N’-((1R,2S,4R,5S,Z)-2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-ylidene)furan-2-carbohydrazide (HL) was prepared from the reaction of furan-2-carbohydrazide with (1R, 2R, 4R, 5S)-2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-one (M1) in ethanol medium. The reaction of the title ligand with selected metal ions Cr(III), Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II) gave complexes with the general formula [M(L)Cl2], (where: M = Cr(III), Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II)). Spectroscopic analyses Fourier transform infrared (FT-IR), Nuclear Magnetic Resonance (NMR) Carbon-13 nuclear magnetic resonance (1H- and 13C-NMR), mass and electronic spectroscopy and atomic absorption) along with elemental microanalysis (C.H.N), chloride percentage, conductivity measurements, magnetic moments and melting point were used to establish the identity of ligand and complexes. The biological activity of the synthesized compounds towards bacterial strains (G+ and G-) was investigated.

In Situ Decoration of ZnSnO3 Nanosheets on the Surface of Hollow Zn2SnO4 Octahedrons for Enhanced Solar Energy Application.

Hierarchical ZnSnO3/Zn2SnO4 porous hollow octahedrons were constructed using the method of combining the acid etching process with the in situ decoration technique for photovoltaic and photocatalytic applications. The composite was used as photoanode of the dye-sensitized solar cells (DSSCs), an overall 4.31% photovoltaic conversion efficiency was obtained, nearly a 73.1% improvement over the DSSCs that used Zn2SnO4 solid octahedrons. The composite was also determined to be a high-performance photocatalyst for the removal of heavy metal ion Cr (VI) and antibiotic ciprofloxacin (CIP) in single and co-existing systems under simulated sunlight irradiation. It was remarkable that the composite displayed good reusability and stability in a co-existing system, and the simultaneous removal performance could be restored by a simple acid treatment. These improvements of solar energy utilization were ascribed to the synergetic effect of the hierarchical porous hollow morphology, the introduction of ZnSnO3 nanosheets, and the heterojunction formed between ZnSnO3 and Zn2SnO4, which could improve light harvesting capacity, expedite electron transport and charge-separation efficiencies.

Antimicrobial and Bioinformatic Modelling Studies of Isatin Mixed Ligand and Some Ternary Chelates

AbstractSynthesis of some ternary complexes with isatin (ISA) as primary ligand and N,N,N,N‐tetramethyl ethylene diamine (TMEDA) as secondary ligand with a series of metal ions (M) Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) is presented. IR, elemental analysis, melting point, molar conductance, mass and thermal analysis were applied to characterize the prepared compounds. Conductometry measurements reveal that all complexes are non‐electrolytes except Cr(III), Mn(II), Fe(III) and Co(II) complexes. In the light of magnetic and solid reflectance techniques, all prepared complexes were suggested in an octahedral geometry. ESR study of Cu(II) complex prove its octahedral geometry. The mixed ligand complexes were found to have the formulae [M(ISA)(TMEDA)Cl2] where M=Ni(II), Cu(II) and Zn(II); [M(ISA)(TMEDA)Cl2]Cln.xH2O in case of M=Cr(III), Fe(III) and Cd(II) (where n=l, x=0 for Cr(III), n=l, x=0 for Fe(III) and n=0, x=2 for Cd(II) and [M(ISA)(TMEDA)Cl(H2O)]Cl in case of M=Mn(II) and Co(II). Antimicrobial activity of some complexes are higher than parent ligands. Molecular docking study confirmed the importance of Cu(II), Ni(II) and Cr(III) complexes as they have the highest interaction with the receptors of crystal structure of S.aureus nucleoside (PDB ID: 3Q8U), E. coli (PDB: 3T88) and protein phosphatase (PPZl) of C. albicans (PDB: 5JPE) with minimum binding energy of −2l.5, −7.2 and −45.6 kcal/mol, respectively.

Adsorption Of Cr(VI) Ions Using Sugar Palm Fruit Peel (Arenga Pinnata) Immobilized in Ca-Alginate Bead

physiological or metabolic processes that can cause cancer in humans. Adsorption is one of the method that is quite effective for removing Cr(VI) in waters because this method uses low cost with good efficiency. Sugar palm fruit peel waste can be used as an adsorbent because it contains active compounds such as carbohydrates, proteins, fats that can play a role in the absorption of metal ions. This sugar palm peel waste will be immobilized using a Ca-alginate medium to increase the absorption of mechanical forces in the adsorption process. The sugar palm fruit peel was activated using 4% NaOH, which was then immobilized by Ca-alginate. The adsorbent was tested to determine its functional group using FTIR and using SEM EDX to see the surface morphology and the elements present in the adsorbent. The results showed that the optimum absorption of metal ions Cr(VI) using Ca-alginate immobilized palm peel as adsorbent at optimum pH 2 with an efficiency of 63% and adsorption capacity of 0.35396 mg/g, the optimum contact time was 75 minutes with an efficiency of 73, 83% and adsorption capacity of 0.41314 mg/g and the optimum concentration at 150 ppm with adsorption capacity of 13.15185 mg/g

Pengaruh pH dan Konsentrasi Pada Penyerapan Ion Logam Cr(VI) Menggunakan Karbon Aktif Kulit Durian

Metal ions Cr (VI) are a type of toxic heavy metal that can cause environmental pollution. Chromium limits exceeding 0.1 mg/L in the water will cause damage to ecosystems and living things within them. Adsorption using activated carbon durian shell was chosen as one of the most efficient methods. Used adsorbent activated carbon durian shell that aims to know the quality of activated carbon durian shell and determine the optimum condition of absorption and optimum capacity of absorption of metal ions Cr (VI). The reaction between orange chromium ions with the addition of H2SO4 and colorless diphenylcarbazide forms a purple solution complex. Maximum wavelength absorption is obtained at 542 nm. The results were obtained with the capacity of immersion in optimum conditions to the absorption of metal ions Cr (VI) at pH 2 and Concentration 360 mg/L with an absorption capacity of 40,3190 mg/g. The study of adsorption isoterm refers more to the freundlich equation approach with a regression coefficient value approaching 1 (R2= 0,9684).

Ab Initio Insight into the Interaction of Metal-Decorated Fluorinated Carbon Fullerenes with Anti-COVID Drugs.

We theoretically investigated the adsorption of two common anti-COVID drugs, favipiravir and chloroquine, on fluorinated C60 fullerene, decorated with metal ions Cr3+, Fe2+, Fe3+, Ni2+. We focused on the effect of fluoridation on the interaction of fullerene with metal ions and drugs in an aqueous solution. We considered three model systems, C60, C60F2 and C60F48, and represented pristine, low-fluorinated and high-fluorinated fullerenes, respectively. Adsorption energies, deformation of fullerene and drug molecules, frontier molecular orbitals and vibrational spectra were investigated in detail. We found that different drugs and different ions interacted differently with fluorinated fullerenes. Cr3+ and Fe2+ ions lead to the defluorination of low-fluorinated fullerenes. Favipiravir also leads to their defluorination with the formation of HF molecules. Therefore, fluorinated fullerenes are not suitable for the delivery of favipiravir and similar drugs molecules. In contrast, we found that fluorine enhances the adsorption of Ni2+ and Fe3+ ions on fullerene and their activity to chloroquine. Ni2+-decorated fluorinated fullerenes were found to be stable and suitable carriers for the loading of chloroquine. Clear shifts of infrared, ultraviolet and visible spectra can provide control over the loading of chloroquine on Ni2+-doped fluorinated fullerenes.

COF TzDa/Ag/AgBr Z-scheme heterojunction photocatalyst for efficient visible light driven elimination of antibiotics tetracycline and heavy metal ion Cr(VI)

Exploring efficient photocatalysts for eliminating coexisting organic pollutants and heavy metal ions is important for sustainable and green environmental purification. Herein, in-situ precipitation-deposition of AgBr onto COF TzDa feasibly fabricated a new heterojunction composite COF TzDa/AgBr, which readily transformed to COF TzDa/Ag/AgBr under exposure to light. The structure, morphology, composition, optical and electrochemical properties of this composite were characterized through various techniques. The activities of COF TzDa/Ag/AgBr in degrading antibiotics tetracycline (TC) and reducing Cr(VI) under simulated visible-light were extensively improved compared with bare COF TzDa, AgBr and their physical mixture. Credited to the synergism among TC, Cr(VI) and the photocatalyst, COF TzDa/Ag/AgBr demonstrated even higher efficiency in simultaneously removing TC/Cr(VI) mixture than for the single pollutant. Furthermore, plausible TC degradation intermediates and pathways were postulated by HPLC-MS analysis. Investigations on band structure, radicals quenching and ESR spectra concluded a Z-scheme charge transfer mechanism with Ag NPs as electron mediator in COF TzDa/Ag/AgBr, which revealed that O2− and h+ were responsible for degrading TC, while photo-generated electrons reduced toxic Cr(VI) to non-toxic Cr(III). The enhanced performance of COF TzDa/Ag/AgBr should stem from the reinforced visible-light adsorption, increased surface areas, accelerated charge transfer and separation, and inhibited Ag/AgBr aggregation. COF TzDa/Ag/AgBr also displayed good stability during the recycled treatment of TC and Cr(VI), while TC degradation under COF TzDa/Ag/AgBr was not obviously influenced by common environmental factors. Thus, this work might offer a promising strategy for the treatment and purification of wastewater containing organic pollutants and heavy metal ions.

Selective Metal Ion Irradiation Using Bipolar HIPIMS: A New Route to Tailor Film Nanostructure and the Resulting Mechanical Properties

This manuscript introduces and experimentally demonstrates a novel concept of selective metal ion irradiation by combining bipolar HIPIMS with conventional DC magnetron sputtering operation and simple DC biasing. The addition of the positive pulse to a conventional HIPIMS discharge accelerates the predominantly metal ions created during the negative HIPIMS phase with an energy proportional to the positive pulse amplitude and ionization state. Two distinct metal elements with large difference in atomic mass (Cr and Nb) are used on this work to irradiate a TiAlN matrix which is being deposited by conventional DCMS. The positive acceleration voltages used for both Cr and Nb discharges were varied between 0 to +200 V to analyze the influence of Nb and Cr metal ion irradiation on the mechanical and microstructural properties of TiAlN films. Even though the total metal ion incorporation into the TiAlN matrix for both Cr and Nb is less than 10% at%, strong effects are observed on the resulting film properties. It was observed that use of the lighter metal ion Cr is more beneficial than the heavier metal ion Nb. The Cr bombardment allows a hardness improvement from 7 to 22 GPa as well as a reduced film accumulated stress at the highest positive acceleration voltage. From the XRD measurements it is observed that the Cr atoms are inserted into the TiAlN cubic matrix maintaining its crystalline structure. However, the bombardment with the high-mass metal ion (Nb) promotes the deformation of the cubic TiAlN matrix, resulting in a spinodal decomposition and further degradation of the crystalline structure with the appearance of the hexagonal wurtzite-type Al-rich phase. This is also translated to the resulting film mechanical properties, as hardness rapidly decreases from 25 to 10 GPa and stress increases linearly with the positive voltage acceleration.

Combinatorial Screening of Cu-W Oxide-Based Photoanodes for Photoelectrochemical Water Splitting.

Metal oxide libraries for photoanodes for the oxygen evolution reaction (OER) were generated by printing a metal salt solution in an array layout, followed by calcination to yield 22 ternary metal oxide systems. The libraries included a ternary metal cation system based on CuWO4 with one out of eight transition or posttransition metal ions Cr, Mn, Fe, Co, Ni, Zn, Bi, and Ga in different overall atomic ratios. The photocatalyst libraries were screened by scanning photoelectrochemical microscopy for the highest anodic photocurrents. Array elements that showed promising performance were printed in another set of eight libraries with smaller increments of overall composition. Improved performance with respect to CuWO4 was found for Ga, Co, and Ni as the third element. A comparison of the most active composition of those arrays within one library showed the highest activity for Cu48Ga3W49Ox. Printing spots of identical composition (Cu48Ga3W49Ox, Cu44Ni9W47Ox, and Cu44Co9W47Ox) over a larger area facilitated further characterization by X-ray photoelectron spectroscopy ultraviolet photoelectron spectroscopy (UPS), X-ray diffraction, scanning electron microscopy, chopped light voltammetry, and scanning electrochemical microscopy for the OER. High and stable steady-state photocurrents were generated in a photoelectrochemical cell for all three electrodes even at a low constant bias voltage. The best overall photoanode composition Cu48Ga3W49Ox showed currents that were 36 times higher than the currents of the binary Cu50W50Ox system. Significant n-doping was found by UPS valence band spectra for Ga-containing materials.