An Imidazole-functionalized Dioxovanadium Complex with the Highly Selective Oxidation of Sulfides

A novel imidazole-functionalized dioxovanadium complex [V2O2（C2O4）（aIM）4] （aIM =1-allylimidazole） was synthesized by the reaction of VO（acac）2 with 1-allylimidazole and fully characterized by single-crystal X-ray diffraction （SCXRD）,powder X-ray diffraction （PXRD）,X-ray photoelectron spectroscopy （XPS）,Fourier transform infrared spectroscopy （FT-IR） and elemental analyses.Interestingly,the oxalate was in-situ generated from the acetylacetone anion of VO（acac）2 and further coordinated with the vanadium cation and finally complex 1 was achieved.The crystal of complex 1 belongs to the monoclinic system,space group P21/n with a =10.7922（9）,b =10.6296（8）,c =13.2936（11） （A）,μ =0.677 mm^-1,Mr =686.48,V =1516.9（2） A^3,Z =2,Dc =1.503 g/cm^3,F（000） =708,R =0.0543,and wR =0.1517 for 2459 observed reflections with Ⅰ 〉 2σ（Ⅰ）.Notably,complex 1 is further used as catalyst in the oxidation of sulfides using H2O2 as the oxidant and exhibits excellent catalytic performance （conv.up to 95.6%,sele.up to 98.9%）.

Lithium cation-doped tungsten oxide as a bidirectional nanocatalyst for lithium-sulfur batteries with high areal capacity

Lithium-sulfur(Li-S) batteries are promising for high energy-storage applications but suffer from sluggish conversion reaction kinetics and substantial lithium sulfide(Li_(2)S) oxidation barrier,especially under high sulfur loadings.Here,we report a Li cation-doped tungsten oxide(Li_(x)WO_(x)) electrocatalyst that efficiently accelerates the S■HLi_(2)S interconversion kinetics.The incorporation of Li dopants into WO_(x) cationic vacancies enables bidirectional electrocatalytic activity for both polysulfide reduction and Li_(2)S oxidation,along with enhanced Li^(+) diffusion.In conjunction with theoretical calculations,it is discovered that the improved electrocatalytic activity originates from the Li dopant-induced geometric and electronic structural optimization of the Li_(x)WO_(x),which promotes the anchoring of sulfur species at favourable adsorption sites while facilitating the charge transfer kinetics.Consequently,Li-S cells with the Li_(x)WO_(x) bidirectional electrocatalyst show stable cycling performance and high sulfur utilization under high sulfur loadings.Our approach provides insights into cation engineering as an effective electrocatalyst design strategy for advancing high-performance Li-S batteries.

Nano-Ni-Induced Electronic Modulation of MoS_(2) Nanosheets Enables Energy-Saving H_(2) Production and Sulfide Degradation

Electrocatalytic hydrogen evolution and sulfion(S^(2-))recycling are promising strategies for boosting H_(2)production and removing environmental pollutants.Here,a nano-Ni-functionalized molybdenum disulfide(MoS_(2))nanosheet was assembled on steel mesh(Ni-MoS_(2)/SM)for use in sulfide oxidation reaction-assisted,energy-saving H_(2)production.Experimental and theoretical calculation results revealed that anchoring nano-Ni on high-surface-area slack MoS_(2)nanosheets not only optimized catalyst adsorption of polysulfides but also played an important role in promoting hydrogen evolution reaction kinetics by absorbing OH_(ad),thereby greatly enhancing the catalytic performance toward sulfide oxidation reaction and hydrogen evolution reaction.Meanwhile,the Ni/MoS^(2-)based hydrogen evolution reaction+sulfide oxidation reaction system achieved nearly 100%hydrogen production efficiency and only consumed 61%less power per kWh than the oxygen evolution reaction+hydrogen evolution reaction system,which suggested our proposed Ni-MoS_(2)and novel hydrogen production system are promising for sustainable energy production.

THE SULFIDATION/OXIDATION RESISTANCE OF TWO Ni-Cr-Al-Y ALLOYS AT 700℃

The high temperature corrosion resistance of Ni-25.9Cr-13.5Al-1.2Y-0.6Si and Ni-10.2Co-12.4Cr16.0Al-0.5Y-0.2Hf alloys was assessed in sulfidation/oxidation envi-ronments. In the environment with a sulfur partial pressure of 1Pa. and an oxygenpartial pressure of 10^(-19)Pa, both these alloys exhibited three distinct stages in theweight gain-time curve when tested at 700℃. In the initial stage, selective sulfidationof Cr suppressed the formation of the other metal sulfides, resulting in lower weightgains. In the transient stage, breakdown and cracking of Cr sulfides and insufficientconcentration of Cr at the outer zone led to the rapid formation of Ni sulfides anda rapid increase in weight. In the steady-state stage, corrosion was controlled by thediffusion of anions and/or cations, which led to a parabolic rate law.

Effect of x-alumina addition on H_2S oxidation properties of pure and modified y-alumina

The influence of the textural and acidic properties ofγ‐Al2O3,(γ+χ)‐Al2O3,and?‐Al2O3on the catalytic activity,selectivity,and stability of direct H2S oxidation has been studied.A comparison of the H2S‐to‐S conversion effectiveness of aluminas with their acidic properties(identified by Fourier transform infrared spectroscopy and temperature programmed desorption of NH3)shows that H2S adsorption occurs predominantly on weak Lewis acid sites(LAS).γ‐Alumina samples containing aχ‐phase and/or modified Mg2+ions have a greater concentration of weak LAS and exhibit greater catalytic activity.When alumina is treated with a sulfuric acid solution,strong LAS appear and the number of LAS decreases significantly.Modification of alumina with hydrochloric acid has a limited effect on LAS strength.Weak LAS are retained and double in number compared to that present in the unmodified alumina,but the treated sample has Al?Cl bonds.Alumina samples modified by sulfate and chloride anions exhibit poor catalytic activity in H2S oxidation.

Four unprecedented V_(14)clusters as highly efficient heterogeneous catalyst for CO_(2)fixation with epoxides and oxidation of sulfides

Chemical fixation of carbon dioxide(CO_(2))is an energy-saving method for alleviating the greenhouse gas emissions,whereas it persists a challenge posed by the demand for efficient catalysts.Herein,four unprecedented examples of tetradecanuclear vanadium clusters,namely,[(C_(2)H_(8)N_(2))6(CH_(3)O)8(CH_(3)OH)_(2)V_(10)^(Ⅳ)V_(4)ⅤO_(26)](V_(14)-1),[(C_(3)H_(10)N_(2))_(6)(CH_(3)O)_(8)(CH_(3)OH)_(2)V_(10)^(Ⅳ)V_(4)ⅤO_(26)](V14^(-2)),[(C_(6)H_(14)N_(2))6(CH_(3)O)8(CH_(3)OH)_(2)V_(10)^(Ⅳ)V_(4)ⅤO_(26)]·5H_(2)O(V14^(-3))and[(C_(4)H_(12)N_(2)O)_(4)(C_(4)H_(11)N_(2)O)_(2)(CH_(3)O)_(2)V_(10)^(Ⅳ)V_(4)ⅤO_(28)]·6H_(2)O(V_(14)-4),have been triumphantly designed and constructed under solvothermal conditions.Among them,compounds V_(14)-1–4 are the first cases of tetradecanuclear vanadium clusters without the introduction of inorganic acid radical ions.Two main units[V_(10)^(Ⅳ)V_(4)ⅤO_(26)]8+and[V10ⅣV4ⅤO28]4+represent brand-new configurations of tetradecanuclear vanadium clusters.Given the fact that the presence of V^(Ⅳ)/V^(Ⅴ)can potentially facilitate electron transfer and consequently expedite catalytic reactions,we explored the catalytic activities of these compounds.Remarkably,V_(14)-1 was further used as a heterogeneous catalyst in the CO_(2)fixation into cyclic carbonates under milder conditions(60℃,0.5 MPa)and exhibited higher catalytic activity.Also,the experimental results indicated that V_(14)-1 could efficiently catalyze the sulfoxidation,which could fully convert most sulfides within 40 min at room temperature.Moreover,as a stable heterogeneous catalyst employed in CO_(2)fixation with epoxides and oxidation of sulfides,V_(14)-1 could be consecutively used multiple cycles without losing its catalytic activity.

Cytochrome P450 Enzyme-Copper Phosphate Hybrid Nano-Flowers with Superior Catalytic Performances for Selective Oxidation of Sulfides

Cytochrome P450 enzyme-copper phosphate hybrid materials with flower-like shape were prepared with a simple but efficient coprecipitation method.The growth process of the hybrid flowers can be divided into three successive steps：coordination/nucleation,growth,and further ripen.The concentration of enzymes in the mother liquor exerted great influence on the morphology and surface enzyme content of the nano-composites.The catalytic performance in the reaction of selective oxidation of sulfide to sulfoxide was also investigated.The hybrid flowers exhibited superior catalytic performance：satisfied thioanisole conversion and selectivity to methyl phenyl sulfoxide （both above 97%） with H2O2 as oxidant under mild reaction conditions,excellent stability and recyclability,and wide scope of substrates.Such results indicate that the hybrid materials are potentially good candidates in the industrial enzyme catalysis.

Profiling of microbial communities in a bioreactor for treating hydrocarbon-sulfide-containing wastewater

A technology of polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)was used to profile the structure and dynamic changes of microbial communities in a bioreactor for treating hydrocarbon-sulfide-containing(HSC)wastewater.The results showed that the heterotrophic genus of Acinetobacter and the autotrophic genera of Thiobacillus and Thiomonas could survive well in all of three operating conditions.Some special genera were also observed with changes of micro-ecoenvironment in the reacto...

Interface Engineering of CoS/CoO@N‑Doped Graphene Nanocomposite for High‑Performance Rechargeable Zn–Air Batteries

Low cost and green fabrication of high-performance electrocatalysts with earth-abundant resources for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are crucial for the large-scale application of rechargeable Zn-air batteries(ZABs).In this work,our density functional theory calculations on the electrocatalyst suggest that the rational construction of interfacial structure can induce local charge redistribution,improve the electronic conductivity and enhance the catalyst stability.In order to realize such a structure,we spatially immobilize heterogeneous CoS/CoO nanocrystals onto N-doped graphene to synthesize a bifunctional electrocatalyst(CoS/CoO@NGNs).The optimization of the composition,interfacial structure and conductivity of the electrocatalyst is conducted to achieve bifunctional catalytic activity and deliver outstanding efficiency and stability for both ORR and OER.The aqueous ZAB with the as-prepared CoS/CoO@NGNs cathode displays a high maximum power density of 137.8 mW cm^−2,a specific capacity of 723.9 mAh g^−1 and excellent cycling stability(continuous operating for 100 h)with a high round-trip efficiency.In addition,the assembled quasi-solid-state ZAB also exhibits outstanding mechanical flexibility besides high battery performances,showing great potential for applications in flexible and wearable electronic devices.

Extending aromatic acids on TiO_(2)for cooperative photocatalysis with triethylamine:Violet light-induced selective aerobic oxidation of sulfides

Designing visible light photocatalysts with a metal oxide semiconductor as the starting material could expand a new horizon for the conversion and storage of solar energy.Here,the benchmark photocatalyst TiO_(2) was used to pursue this goal by anchoring aromatic acids.Extending the aromatic acid was strategically deployed to design TiO_(2) complexes with violet light-induced selective aerobic oxidation of sulfide as the probe reaction.With benzoic acid(BA)as the initial molecule,horizontally extending one or two benzene rings furnishes 2-naphthoic acid(2-NA)and 2-anthracene acid(2-AA).Moreover,triethylamine(TEA),an electron transfer mediator,was introduced to maintain the integrity of the anchored aromatic acids.Notably,there was a direct correlation between theπ-conjugation of aromatic acid ligand and the selective aerobic oxidation of sulfides.Among the three aromatic acids,2-AA delivered the best result over TiO_(2) due to the most extensiveπ-conjugated system.Ultimately,violet light-induced selective aerobic oxidation of sulfides into corresponding sulfoxides was conveniently realized by cooperative photocatalysis of 2-AA-TiO_(2) with 10 mol%of TEA.This work affords an extending strategy for designing the next-generation ligands for semiconductors to expand visible light-induced selective reactions.

Characterization of sulfide oxidation and optimization of sulfate production by a thermophilic Paenibacillus naphthalenovorans LYH-3 isolated from sewage sludge composting

The sulfur-containing odor emitted from sludge composting could be controlled by sulfide oxidizing bacteria, yet mesophilic strains show inactivation during the thermophilic stage of composting. Aimed to investigate and characterize the thermotolerant bacterium that could oxidize sulfide into sulfate, a heterotrophic strain was isolated from sewage sludge composting and identified as Paenibacillus naphthalenovorans LYH-3. The effects of various environmental factors on sulfide oxidation capacities were studied to optimize the sulfate production, and the highest production rate (27.35%±0.86%) was obtained at pH 7.34, the rotation speed of 161.14 r/min, and the inoculation amount of 5.83%by employing BoxBehnken design. The results of serial sulfide substrates experiments indicated that strain LYH-3 could survive up to 400 mg/L of sulfide with the highest sulfide removal rate (88.79%±0.35%) obtained at 50 mg/L of sulfide. Growth kinetic analysis presented the maximum specific growth rateμm(0.5274 hr-1) after 22 hr cultivation at 50℃. The highest enzyme activities of sulfide quinone oxidoreductase (0.369±0.052 U/mg) and sulfur dioxygenase (0.255±0.014 U/mg) were both obtained at 40℃, and the highest enzyme activity of sulfite acceptor oxidoreductase (1.302±0.035 U/mg) was assessed at 50℃. The results indicated that P. naphthalenovorans possessed a rapid growth rate and efficient sulfide oxidation capacities under thermophilic conditions, promising a potential application in controlling sulfur-containing odors during the thermophilic stage of sludge composting.

Sulfide-based ATP production in Urechis unicinctus

We measured sulfide-based ATP production by isolated mitochondria from four tissues of Urechis unicinctus and the effects of inhibitors of respiratory complexes on ATP production were evaluated. The results show that these mitochondria could oxidize sulfide to produce ATP. The yield of sulfide-stimulated ATP varied from 5 nmol ATP/min/mg to 90 nmol ATP/min/mg according to the sulfide concentration and the source of the mitochondria. The maximum ATP synthesis occurred in hindgut mitochondria using 5 μmol/L sulfide as a substrate. The effects of inhibitors (Rotenone, Antimycin A, Cyanide, and Salicylhydroxamic acid) on mitochondrial ATP production varied with the source of the mitochondria. Our results indicate that sulfide-based ATP production and the associated electron transport pathway are tissue-specific in U. unicinctus.

Solid-state Syntheses, Crystal Chemistry and Optical Properties of Two Europium Oxide/sulfide Silicates, Eu2O(SiO4) and Eu5S(SiO4)3

Two europium oxide/sulfide silicates, Eu2O（SiO4） （1） and Eu5S（SiO4）3 （2）, have been synthesized using high-temperature solid-state reactions. 1 crystallizes in the monoclinic space group P21/c with a = 9.1459（7）, b = 7.1280（5）, c = 6.7655（5） ？ and ？ = 107.611（2）, belonging to the Gd2O（SiO4） structure type; 2 crystallizes in space group P63/m of the hexagonal system with a = 9.786（4） and c = 6.789（3） , belonging to the apatite Ca5Cl（PO4）3 structure type. The structure chemistry of related RE2O（SiO4） and RE5S（SiO4）3 compounds is also discussed. The optical energy gap of 2 is determined to be 2.05 eV.

Experimental Design Technique on Removal of Hydrogen Sulfide using CaO-eggshells Dispersed onto Palm Kernel Shell Activated Carbon：Experiment,Optimization,Equilibrium and Kinetic Studies

This study presents the use of chicken eggshells waste utilizing palm kernel shell based activated carbon（PKSAC） through the modification of their surface to enhance the adsorption capacity of H2S. Response surface methodology technique was used to optimize the process conditions and they were found to be： 500 mg/L for H2S initial concentration, 540 min for contact time and 1 g for adsorbent mass. The impacts of three arrangement factors（calcination temperature of impregnated activated carbon（IAC）, the calcium solution concentration and contact time of calcination） on the H2S removal efficiency and impregnated AC yield were investigated. Both responses IAC yield（IACY, %） and removal efficiency（RE, %） were maximized to optimize the IAC preparation conditions. The optimum preparation conditions for IACY and RE were found as follows： calcination temperature of IAC of 880 ℃, calcium solution concentration of 49.3% and calcination contact time of 57.6 min, which resulted in 35.8% of IACY and 98.2% RE. In addition, the equilibrium and kinetics of the process were investigated. The adsorbent was characterized using TGA, XRD, FTIR, SEM/EDX, and BET. The maximum monolayer adsorption capacity was found to be 543.47 mg/g. The results recommended that the composite of PKSAC and Ca O could be a useful material for H2S containing wastewater treatment.

Organic reactions in chiral micelles 7.The structural effects on the asymmetric oxidation of prochiral sulfides in chiral micelles

A variety of phenyl alkyl sulfides were oxidized enantioselectively with NaIO_4 in chiral micellar systems formed from eight chiral surfactants,to give optical active sulfoxides.The enantiomer excesses ranged from 1.6 to 15.0%.To understand the mechanistic detail of this asymmetric oxi- dation in chiral micelle,the effects of structure both in substrates and surfactants on the optical yield of the oxidation were studied and discussed.Generally,increasing the alkyl chain length both in sur- factants and in substrates enhances the optical yield,also the surfactant with hydroxy group at its appropriate position gives better enantioselectivity,suggesting the enzymic characteristics of the chiral micelle.

Magnetic separation of metal sulfides/oxides by Fe3O4 at room temperature and atmospheric pressure

The recovery of heterogeneous catalysts can save costs and avoid secondary pollution,but its separation efficiency and recovery cost are limited by conventional separation methods such as precipitation–flocculation,centrifugation and filtration.In this paper,we found that surface-defective metal sulfides/oxides(WS2,CuS,ZnS,MoS2,CdS,TiO2,MoO2 and ZnO)commonly used in advanced oxidation processes(AOPs)could be magnetically recovered at room temperature and atmospheric pressure by mechanically mixing with Fe3O4.Zeta potential,Raman,X-ray photoelectron spectroscopy(XPS)and electro-spin resonance(ESR)spectra were measured to explore the mechanism of the magnetic separation phenomenon.The exposed active metal sites on the surface of defective metal sulfides/oxides are beneficial for the formation of chemical bonds,which are combined with electrostatic force to be responsible for the magnetic separation.Moreover,other factors affecting the magnetic separation were also investigated,such as the addition of amount of Fe3O4,different solvents and particle sizes.Finally,WS2 was chosen to be applied as a co-catalyst in Fenton reaction,which could be well separated by the magnetic Fe3O4 to achieve the recycle of catalyst in Fenton reaction.Our research provides a general strategy for the recycle of metal sulfides/oxides in the catalytic applications.

Sulfide oxidation in fluidized bed bioreactor using nylon support material

A continuous fluidized bed bioreactor （FBBR） with nylon support particles was used to treat synthetic sulfide wastewater at different hydraulic retention time of 25, 50 and 75 min and upflow velocity of 14, 17 and 20 m/hr. The effects of upflow velocity, hydraulic retention time and reactor operation time on sulfide oxidation rate were studied using statistical model. Mixed culture obtained from the activated sludge, taken from tannery effluent treatment plant, was used as a source for microorganisms. The diameter and density of the nylon particles were 2-3 mm and 1140 kg/m3, respectively. Experiments were carried out in the reactor at a temperature of （30 ± 2）°C, at a fixed bed height of 16 cm after the formation of biofilm on the surface of support particles. Biofilm thickness reached （42 ± 3） μm after 15 days from reactor start-up. The sulfide oxidation, sulfate and sulfur formation is examined at all hydraulic retention times and upflow velocities. The results indicated that almost 90%-92% sulfide oxidation was achieved at all hydraulic retention times. Statistical model could explain 94% of the variability and analysis of variance showed that upflow velocity and hydraulic retention time slightly affected the sulfide oxidation rate. The highest sulfide oxidation of 92% with 70% sulfur was obtained at hydraulic retention time of 75 min and upflow velocity of 14 m/hr.

Decavanadate-based Transition Metal Hybrids as Bifunctional Catalysts for Sulfide Oxidation and C-C Bond Construction

The development of bifunctional catalysts has drawn much attention in realizing efficient and feasible catalytic systems to meet the diverse dema nd of pote ntial industrial applications.Desig n of stable and powerful bifun ctional catalysts for various catalysis systems is highly desirable yet largely unmet.Here,three kinds of decavanadate-based transition metal hybrids(DTMH)(i.e.,Co-DTMH,Ni-DTMH and Ag-DTMH)have been successfully synthesized through a pH tuning strategy and further characterized.Specifically,the rare M05N six-coordinated transition metal coordination modes have been detected in Co-DTMH and Ni-DTMH,while Ag atoms in Ag-DTMH exhibited three-and five-coordinated geometries with the tuning of specially selected imidazole ligands.Thus-obtained clusters can serve as powerful bifunctional catalysts for both sulfide oxidation and C-C bond construction.Remarkably,Ag-DTMH dem on st rated excellent heteroge ne ous bifunctional catalytic properties in the selective oxidati on of sulfides and construction of C-C bond(yields up to 99%),which enable successful recycling for three cycles with remained catalytic activities and structure stability.The newly designed decavanadate-based transition metal hybrids with bifunctional property hold high promise in the practical applications like continuous catalysis or flow bed reactions.

CATALYTIC PROPERTIES OF NANOFIBROUS CARBON IN SELECTIVE OXIDATION OF HYDROGEN SULPHIDE

Nanofibrous carbonaceous materials （NFC） as a new class of materials having many applications, can catalyze the selective oxidation of H2S to sulfur. The correlation between NFC structure and its activity and selectivity in H2S oxidation was determined. It is demonstrated that selectivity can be improved if NFC with more ordered structure be synthesized and the portion of the original catalyst in carbon be reduced by increasing the carbon accumulated in the catalyst.

Two pseudo-polymorphic porous POM-pillared MOFs for sulfide-sulfoxide transformation: Efficient synergistic effects of POM precursors, metal sites and microstructures

Developing sustainable and powerful heterogeneous catalytic systems to convert sulfides into high-value sulfoxide products has become a particularly appealing field and an arduous challenge.In this work,two porous polyoxometalate-pillared metal-organic frameworks,formulated as H_(3n)[Cu_(3)(pidc)_(2)(H_(2)O)_(2.5)]_(2)[PW_(12)O_(40)]_n·x H_(2)O (n=1.5,x=6 for 1,n=1,x=12 for 2;and H_(3)pidc=2-(3-pyridinyl)-1H-imidazole-4,5-dicarboxylic acid),were consciously manufacture and employed for heterogeneously catalyzed sulfide-sulfoxide transformation.Structural analysis shows that 1 and 2 exhibit similar porous frameworks with nearly identical two-dimensional metal-organic layers further pillared by tetradentate POM ligands with different coordination modes,which also result in the porosity of 1 being almost twice that of 2.In catalyzing the conversion of methyl phenyl sulfide (MPS) to methyl phenyl sulfoxide (MPSO),1 can convert nearly 100%of MPS into MPSO within 30 min,while 2 achieved the similar results requires 50 min.The higher activity of 1 may be attributed to its larger channel that can provide more active sites and more efficient mass transfer process.Systematic structure-activity analyses and mechanistic studies revealed dual-reaction pathways driven by POM sites and metal sites assisted by the structural microenvironment.