查看更多>>摘要：Bifunctional catalysts for hydrogen/oxygen evolution reactions(HER/OER)are urgently needed given the bright future of water splitting hydrogen production technology.Here,the self-supporting N and Ce dual-doped NiCoP nanoarrays(denoted N,Ce-NiCoP/NF)grown on Ni foam are successfully constructed.When the N,Ce-NiCoP/NF simultaneously acts as the HER and OER electrodes,the voltages of 1.54 and 2.14 V are obtained for driving 10 and 500 mA.cm-2 with a robust durability,and demonstrate its significant potential for practical water electrolysis.According to both experiments and calculations,the electronic structure of NiCoP may be significantly altered by strategically incorporating N and Ce into the lattice,which in turn optimizes the Gibbs free energy of HER/OER intermediates and speeds up the water splitting kinetics.Moreover,the sprout-shaped morphology significantly increases the exposure of active sites and facilitates charge/mass transfer,thereby augmenting catalyst performance.This study offers a potentially effective approach involving the regulation of anion and cation double doping,as well as architectural engineering,for the purpose of designing and optimizing innovative electrocatalysts.
查看更多>>摘要：Immobilization of D-amino acid dehydrogenase(DAADH)by the assembly of peptide linker was studied for the biosynthesis of D-phenylalanine.Hybrid material of zeolitic imidazolate framework-8(ZIF-8)combined with reduced graphene oxide(RGO)was applied for the immobilization of DAADH from Ureibacillus thermosphaericus.The recovery rate of DAADH/ZIF-8/RGO was 165.6％.DAADH/ZIF-8/RGO remained 53.4％of its initial activity at 50 ℃ for 10 h while the free enzyme was inactivated.DAADH/ZIF-8/RGO maintained 70.5％activity in hyperalkaline solution with pH 12.Kinetic parameters indicated that DAADH/ZIF-8/RGO had greater affinity of phenylpyruvate as Vmax/Km of DAADH/ZIF-8/RGO was 1.27-fold than free enzyme.After seven recycles,the activity of DAADH/ZIF-8/RGO remained 64.3％.Furthermore,one-step separation and in situ immobilization of DAADH by ZIF-8/RGO/Ni was carried out with 1.5-fold activity enhancement.Combining peptide linker and metal-organic framework(MOF)immobilization,thermostability and activity of the immobilized DAADH were significantly improved.
查看更多>>摘要：Defect modulation currently plays a decisive role in addressing the poor photoabsorption,sluggish electron hole separation,and high CO2 activation barrier in photocatalytic CO2 reduction.However,hunting for a straightforward strategy to balance the concentration of oxygen vacancy and metal cation defect in one photocatalyst is still a great challenge.Herein,a bismuth vacancies BiOBr nanosheets(BiOBr-1)on the exposed[001]facets were constructed via an acetic acid molecule modification strategy,which can repair oxygen defect by bismuth vacancy in low-temperature solid-state chemical method.Benefiting from the formed bismuth defects that can not only broaden light absorption and elevate charge separation efficiency,but also enhance adsorption and activation of CO2 molecules,the evolution rates of photocatalytic CO2 conversion into CO(71.23 μmol·g-1·h-1)and CH4(8.90 μmol·g-1·h-1)attained by BiOBr-1 are superior 7.1 and 11 times to that of plate-like BiOBr.The photocatalytic mechanisms including adsorption concentration and activation process of CO2 are further revealed by the in situ diffuse reflectance infrared flourier transform spectra(DRIFTS).This finding of the existence of distinct defects in ultrathin nanosheets undoubtedly leads to new possibilities for photocatalyst design using two-dimensional materials with high solar-driven photocatalytic activity.
查看更多>>摘要：Harvesting clean energy from water evaporation has been extensively investigated due to its sustainability.To achieve high efficiency,energy conversion materials should contain multiple features which are difficult to be simultaneously obtained from single-component materials.Here we use composite laminar membranes assembled by nanosheets of graphene oxide and mica,and find a sustained power density induced by water evaporation that is two orders of magnitude larger than that from membranes made by either of the components.The power output is attributed to selective proton transport driven by water evaporation through the interlayer nanochannels in the membranes.This process relies on the synergistic effects from negatively charged and hydrophilic mica surfaces that are important for proton selectivity and water transport,and the tunable electrical conductivity of graphene oxide that provides optimized internal resistance.The demonstrated composite membranes offer a strategy of enhancing power generation by combining the advantages from each of their components.
查看更多>>摘要：Dust particles emitted from smelters can be hazardous to ecosystems and humans,as they are often enriched in metallic compounds.Here,we combined multi-method mineralogical analysis with a sophisticated size sorting approach for copper smelting dust to study the nanosize-effect on heavy metal distribution,which has hitherto been underestimated.Three types of dust were collected from a copper flash smelter and then size-sorted using a Dekati low-pressure impactor.Results showed that all three samples could easily sort out nanoscale dust particles(＜1 μm,grades 10-2)and even those smaller than 100 nm(grades 5-2).Especially for electrostatic precipitators dust,the mass fraction of nanoscale dust(＜1 μm)could reach 10.71％.The presence of heavy metals(Pb,Zn,Cu,and As)and their mineral species in dust was examined at various particle sizes.It was discovered that different heavy metals are enriched on nanoparticles in specific sizes.In micron-sized particles,heavy metals are generally found in discrete phases(e.g.,CuSO4,PbSO4,and As2O3).In nanoscale particles,the dominant phase is Fe3O4,while heavy metals are mostly found in lattice substitution(e.g.,CuFe2O4 and ZnFe2O4).Two distinct nano-dust morphologies were found:One with irregular mesh or chain structures consisting of particles of a few nanometers,and the other with polygonal crystals in larger sizes of hundreds of nanometers.The enrichment of heavy metals in the latter morphology is more pronounced,possibly because lattice substitution of heavy metals is more likely to occur when polycrystalline particles are formed.
查看更多>>摘要：Advanced soft ion-conducting hydrogels have been developed rapidly in the integrated portable health monitoring equipment due to their higher sensitivity,sensory traits,tunable conductivity,and stretchability for physiological activities and personal healthcare detection.However,traditional hydrogel conductors are normally susceptible to large deformation and strong mechanical stress,which leads to inferior electro-mechanical stability for real application scenarios.Herein,a strong ionically conductive hydrogel(poly(vinyl alcohol)-boric acid-glycerol/sodium alginate-calcium chloride/electrolyte ions(PBG/SC/EI))was designed by engineering the covalently and ionically crosslinked networks followed by the salting-out effect to further enhance the mechanical strength and ionic conductivity of the hydrogel.Owing to the collective effects of the energy-dissipation mechanism and salting-out effect,the designed PBG/SC/EI with excellent structural integrity and robustness exhibits exceptional mechanical properties(elongation at break for 559.1％and tensile strength of 869.4 kPa)and high ionic conductivity(1.618 S·m-1).As such,the PBG/SC/EI strain sensor features high sensitivity(gauge factor=2.29),which can effectively monitor various kinds of human motions(joint motions,facial micro-expression,faint respiration,and voice recognition).Meanwhile,the hydrogel-based Zn||MnO2 battery delivers a high capacity of 267.2 mAh·g-1 and a maximal energy density of 356.8 Wh·kg-1 associated with good cycle performance of 71.8％capacity retention after 8000 cycles.Additionally,an integrated bio-monitoring system with the sensor and Zn||MnO2 battery can accurately identify diverse physiological activities in a real-time and non-invasive way.This work presents a feasible strategy for designing high-performance conductive hydrogels for highly-reliable integrated bio-monitoring systems with excellent practicability.
查看更多>>摘要：LiNi0.8Co0.1Mn0.1O2(NCM811),a Ni-rich layered oxide,is a promising cathode material for high-energy density lithium-ion batteries(LIBs).However,its structural instability,caused by adverse phase transitions and continuous oxygen release,as well as deteriorated interfacial stability due to excessive electrolyte oxidative decomposition,limits its widespread application.To address these issues,a new concept is proposed that surface targeted precise functionalization(STPF)of the NCM811 cathode using a synergistic slurry additive(SSA)approach.This approach involves coating the NCM811 particle surface with 3-aminopropyl dimethoxy methyl silane(3-ADMS),followed by the precise deposition of ascorbic acid via an acid-base interaction.The slurry additives induce the formation of an ultra-thin spinel surface layer and a stable cathode-electrolyte interface(CEI),which enhances the electrochemical kinetics and inhibits crack propagation.The STPF strategy implemented by the SSA approach significantly improves the cyclic stability and rate performance of the NCM811 cathode in both half-cell and full-cell configurations.This work establishes a promising strategy to enhance the structural stability and electrochemical performance of nickel-rich cathodes and provides a feasible route to promote practical applications of high-energy density lithium-ion battery technology.
查看更多>>摘要：Porous heterogeneous lyophobic systems(HLSs)find potential applications in energy restoring,dissipating,and absorbing.However,the development of controllable HLSs still lacks rational structure design of nanoporous materials matching the molecular sizes of adopted liquids.Besides that,thoroughly understanding the underlying transportation mechanism in the confined nano channels is greatly challenging.In this work,a series of Co/Zn bimetallic zeolitic imidazolate frameworks(ZIFs)with tunable structures were synthesized via regulating the Co to Zn ratios and employed to investigate the intrusion-extrusion of liquid water in confined nanopores.Structural characterizations confirm the heterometallic coordination in the Co/Zn-doped frameworks.Water intrusion-extrusion experiments unlock the relationship between the intrusion pressure and the nanopore size and realize the evolution of the HLSs between molecular spring and shock-absorber.In addition,cycling tests indicate the reversible structure change of Co/Zn ZIFs encountering pressure-induced water intrusion.In combination with molecular dynamics simulations,we present that the water multimers intrude into nanopores of ZIFs in chain-like forms along with dissociation of hydrogen bonds(HBs).Water molecules in the pre-intrusion state exhibit reduced HBs in response to the increase of pressure and linear structure with 1.6-3.0 HBs on average.After transition to the post-intrusion situation,the associative configuration of water tends to exhibit the tetrahedral structure.Herein,we highlight the roles of pore size and HB in synergically dominating the pressure-induced intrusion-extrusion of liquid water in hydrophobic nanopores.Furthermore,the present work can also guide the development of functional guest-host systems based on porous architectures.
查看更多>>摘要：Propylene epoxidation by H2 and O2 to propylene oxide(PO)over the Au-Ti bifunctional catalysts,as an ideal reaction for PO production,has attracted great interest.Revealing the mechanism of acrolein formation is of great importance for understanding the mechanism of molecular oxygen activation and the formation of hydroperoxo species on the Au sites.Here,we investigate the reaction mechanism of propylene oxidation to acrolein on the Au/uncalcined TS-1(Au/TS-1-B)catalyst through a combination of multiple characterization,H2/D2 exchange,kinetics experiment,and modeling.The Ti sites are found to be non-essential to acrolein formation.Moreover,the acrolein formation on the Au/TS-1-B catalyst is confirmed to be promoted by H2 through hydroperoxo species formation,which includes two main steps:propylene dehydrogenation to*C3H5 with the aid of*OOH species,and*C3H5 oxidation by*OOH to acrolein.The latter step is determined to be the rate-determining step because the corresponding kinetics model gives the best description for experimental results.This work not only provides kinetics insights for the propylene hydro-oxidation to acrolein on the Au-Ti bifunctional catalysts,but also facilitates the rational design of Au catalysts with high activity and selectivity in the direct propylene epoxidation with H2 and O2.
查看更多>>摘要：Organo-chromium(Ⅲ)complex is one of the chromium contaminant species,which would transform to high-toxic Cr(Ⅵ)during migrating in the environment.Such natural organo-chromium(Ⅲ)(NOCr)is difficult to remove by traditional degradation or precipitation methods,due to its high stability and solubility.Herein,we demonstrated a novel NOCr removing method by transforming it to certain structures similar to Cr-Fe minerals in nature,through a self-circulating decomplex and immobilization mechanism with nano zero-valent iron(nZVI).Taking chromium glycinate(Cr-Gly)as a probe,nZVI showed a high Cr removal efficiency of 99.4％under ambient conditions.The removal process included three stages of adsorption,decomplexation,and re-immobilization.Cr-Gly was first adsorbed on the surface of nZVI by chemisorption of the oxide shell.Then,the adsorbed Cr-Gly was decomplexed and oxidized to Cr(Ⅵ)by OH and 1O2,which were generated from molecular oxygen activated by nZVI.Meanwhile,the released Cr(Ⅵ)could be in-situ adsorbed and re-reduced to Cr(Ⅲ),which was further immobilized in form of Cr-O-Fe complex.As the Cr-O-Fe complexing structure was similar to that of Cr-Fe minerals(such as chromohercynite)in nature,this work explored a novel and efficient NOCr removing method that was potential to weaken chromium pollution in the environment.
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