Mass Spectrometric Studies of Selective Oxidation of n-Butane over a Vanadium Phosphorus Oxide Catalyst

The selective oxidation of n-butane to maleic anhydride (MA) on a vanadium-phosphorus oxide (VPO) catalyst was studied using on-line gas-chromatography combined with mass spectrometry(GC-MS) and transient response technique. The reaction intermediates, buterie and furan, were found in the reaction effluent under near industrial feed condition (3% butane+15%O2), while dihydrofuran was detected at high butane concentration (12% butane, 5%O2). Some intermediates of MA decomposition were also identified. Detection of these intermediates shows that the vanadium phosphorus oxides are able to dehydrogenate butane to butene, and butene further to form MA. Based on these observations, a modified scheme of reaction network is proposed. The transient experiments show that butane in the gas phase may directly react with oxygen both on the surface and from the metal oxide lattice, without a proceeding adsorption step. Gas phase oxygen can be adsorbed and transformed to surface lattice oxygen but it can not participate in selective oxidation. Adsorbed oxygen leads to deep oxidation, while lattice oxygen leads to selective oxidation.

A novel phosphorus oxide quantum dots as an emissive nanomaterial for inorganic ions screening and bioimaging

In this work,a novel blue-green fluorescence phosphorous oxide quantum dots(PO QDs)was synthesized by solvothermal method in N-methyl-2-pyrrolidone(NMP)solution without any protection treatment during synthesis.Upon excitation at 400 nm,PO QDs emitted blue-green fluorescence with quantum yield of 0.28.PO QDs exhibited the high inertness to air or moisture,the excellent water solubility,and stable emission intensity in a wide pH range and in high ionic strength solution.Interestingly,PO QDs could give the positive optical response to iron ions(Fe^(3+))and iodine ion(I^(-)).The photoluminescence(PL)of PO QDs could be directly quenched by Fe^(3+).While I^(-)quenched the PO QDs PL by means of Ag^(+)-mediated PO QDs system via the internal filtration effects(IFE)induced by the formation of AgI.Moreover,the biocompatibility and low toxicity of PO QDs verified in bean sprout and Hela cells indicated the promising application of PO QDs in medicine related fields.Furthermore,PO QDs could also be utilized in luminescent composite film for various application scenarios.

Progress of vanadium phosphorous oxide catalyst for n-butane selective oxidation

The utilization of lighter alkanes into useful chemical products is essential for modern chemistry and reducing the CO_(2)emission.Particularly,n-butane has gained special attention across the globe due to the abundant production of maleic anhydride(MA).Vanadium phosphorous oxide(VPO)is the most effective catalyst for selective oxidation of n-butane to MA so far.Interestingly,the VPO complex exists in more or less fifteen different structures,each one having distinct phase composition and exclusive surface morphology and physiochemical properties such as valence state,lattice oxygen,acidity etc.,which relies on precursor preparation method and the activation conditions of catalysts.The catalytic performance of VPO catalyst is improved by adding different promoters or co-catalyst such as various metals dopants,or either introducing template or structural-directing agents.Meanwhile,new preparation strategies such as electrospinning,ball milling,hydrothermal,barothermal,ultrasound,microwave irradiation,calcination,sol-gel method and solvothermal synthesis are also employed for introducing improvement in catalytic performance.Research in above-mentioned different aspects will be ascribed in current review in addition to summarizing overall catalysis activity and final yield.To analyze the performance of the catalytic precursor,the reaction mechanism and reaction kinetics both are discussed in this review to help clarify the key issues such as strong exothermic reaction,phosphorus supplement,water supplement,deactivation,and air/n-butane pretreatment etc.related to the various industrial applications of VPO.

Structure and Stability of P_lO_m Cages and Their Highly Charged Protonated Clusters P_lO_mH_n^(n+):Insight from Density Functional Calculations

Density functional calculations are used to determine structural and electronic properties of P4,P4O6,P4O10,P20O30 and P20O50 clusters and their protonated derivatives.These oxygen-rich phosphorus oxides are predicted to have relatively high stabilities with respect to their components P4 and O2,and their unsaturated P and end-on O atoms as the proton acceptor can accommodate multiple protons to generate highly positively charged cationic clusters,such as P20O30H1010＋.Calculations indicate that P4O6 and P20O30 have higher reactivity toward the proton capture than the P4,P4O10 and P20O50 clusters,and the most stable protonated clusters among these different series of cationic clusters are P4H2……2＋,P4O6H2^2＋,P4O10H3^3＋,P20O30H4^4＋ and P20O50H4^4＋,respectively.The cage skeleton of the phosphorus oxide clusters shows high stability for the consecutive protonation,and the unsymmetrical stretching of the skeletal P-O bond and the wagging mode of P-H coupled with the P-O bond stretching have strong adsorptions.These computational findings are useful for further experimental and theoretical studies of novel phosphorus oxide clusters and their highly positively charged derivatives.

From ultra-low friction to superlubricity state of black phosphorus:Enabled by the critical oxidation and load

Based on the density functional theory(DFT),we investigate the friction properties of inevitable oxidized black phosphorus(o-BP).o-BP with the weaker interlayer adhesion exhibits their great potential as a solid lubricant.At the zero load,the friction property of o-BP is adjusted by its oxidation degree.Expressly,ultra-low friction of P4O2(50%oxidation,O:P=2:4=50%)is obtained,which is attributed to the upper O atoms with lower sliding resistance in the O channel formed by lower layer O atoms.More attractive,we observe superlubricity behavior of o-BP at the critical load/distance due to the flattening potential energy surface(PES).The flattening PES is controlled by the electrostatic role for the high-load(P4O3,O:P=3:4=75%),and by the electrostatic and dispersion roles for the low-load(P4O2).Distinctly,the transform from ultra-low friction to superlubricity state of black phosphorus(BP)can be achieved by critical oxidation and load,which shows an important significance in engineering application.In addition,negative friction behavior of o-BP is a general phenomenon(Z>Z_(min),Z_(min)is the interlayer distances between the outermost P atoms of minimum load.),while its surface-surface model is different from the fold mechanism of the tip-surface model(Z_(0)<Z<Z_(min),Z_(0)is the interlayer distances between the outermost P atoms of equilibrium state.).Thus,this phenomenon cannot be captured due to the jump effect with instability of the atomic force microscopy(AFM)(Z>Z_(min)).In summary,o-BP improves the friction performance and reduces the application limitation,comparing to graphene(Gr),MoS2,and their oxides.

Ultrafast nonlinear absorption and nonlinear refraction in few-layer oxidized black phosphorus

We experimentally investigated the nonlinear optical response in few-layer oxidized black phosphorus(OBP) by the femtosecond Z-scan measurement technique, and found that OBP not only possesses strong ultrafast saturable absorption but also a nonlinear self-defocusing effect that is absent in black phosphorus(BP). The saturable absorption property originates mainly from the direct band structure, which is still maintained in OBP. The emergence of self-defocusing might originate from the combined consequences of the oxygen-induced defects in BP. Our experimental findings might constitute the first experimental evidence on how to dynamically tune its nonlinear property, offering an inroad in tailoring its optical properties through chemical modification(oxidation, introducing defects, etc.). The versatile ultrafast nonlinear optical properties(saturable absorption and self-defocusing) imply a significant potential of the layered OBP in the development of unprecedented optoelectronic devices, such as mode lockers, optical switches, laser beam shapers, and wavelength converters.

Oxidized Black Phosphorus Nanosheets as an Inorganic Antiresorptive Agent

Black phosphorus(BP)is a newly discovered two-dimensional material that has promising applications from bioelectronics to biomedicine.However,facile oxidation of BP leads to changes in surface chemical composition and physical properties,often being referred to as the degradation process of BP.Degradation products of BP nanosheets,namely,oxidized BP nanosheets(oBPNSs),are routinely considered as by-products without many uses.Herein,we found that oBPNSs displayed excellent osteoclastogenesis inhibition effects without impairing cell viability.In contrast to the classic antiresorptive bisphosphonate drugs,oBPNSs showed a different mode of action by suppressing the maturation of osteoclasts.Bone resorption assays,osteoclast actin ring analysis,and tartrate-resistant acid phosphate activity assay results indicated that oBPNSs suppressed receptor activator of nuclear factor-κB(NF-κB)ligand(RANKL)-induced osteoclastogenesis in a dose-and oxidation-dependent manner.Transcriptomic and proteomic analyses indicated that oBPNSs inhibited the activation of the NF-κB signaling pathway and phosphorylation of mitogen-activated protein kinase(MAPK)in differentiated osteoclasts,as confirmed by Western blot analysis.Our results suggest that oBPNSs might be potential antiresorptive nanomaterials to treat osteoporosis.