Improving feed intake and rumen fermentation in lambs using mixed-dimensional attapulgite clay to adsorb naturally occurring mycotoxins.

This experiment was conducted to evaluate the effects of including a mixed-dimensional attapulgite clay (MDA) into a naturally moldly diet for Hu lambs. Fifty male Hu lambs with similar initial body weight (28.24 ±â€…1.80 kg) were randomly allocated into five dietary treatments: a basal diet containing naturally occurring mycotoxins with 0, 0.5, 1.0, and 2.0 kg/t MDA, and basal diet with a commercial mycotoxin adsorbent Solis with montmorillonite as the major component at 1 kg/t. Both MDA and Solis increased average daily gain (ADG) and dry matter intake (DMI; P ≤ 0.004), and there was no difference in growth performance between MDA and Solis (P ≥ 0.26). The final body weight, DMI, and ADG were linearly increased with increasing MDA supplementation (P < 0.01). Lambs treated with both MDA and Solis demonstrated greater apparent digestibility of dry matter (DM), organic matter (OM), and energy compared with the control group (P ≤ 0.03), and there were no differences in nutrient digestibilities between MDA and Solis (P ≥ 0.38). Digestibility of CP was linearly increased with the increasing MDA supplementation (P = 0.01). Neither MDA nor Solis affected rumen total volatile fatty acid (TVFA) concentration (P ≥ 0.39), but decreased the acetate-to-propionate ratio and molar proportion of n-butyrate (P ≤ 0.01), and MDA also increased the concentration of ammonia (P = 0.003). Besides, increasing MDA supplementation linearly reduced the acetate-to-propionate ratio and molar proportion of n-butyrate (P = 0.01), but linearly and quadratically increased the concentration of ammonia (P ≥ 0.003). These results showed that the incorporation of MDA into a naturally moldy diet of Hu lambs yielded comparable results to the Solis product, with higher growth performance and nutrient digestibility but lower acetate-to-propionate ratio observed. In conclusion, including ≥ 1 kg/t of MDA in high mycotoxin risk diets for growing lambs improves feed intake and rumen fermentation.

The issue of mycotoxin-contaminated animal feed has consistently presented a significant challenge in relation to animal health and production. The mixed-dimensional attapulgite clay (MDA) has been proven effective in binding polar mycotoxins such as aflatoxin, while also effectively adsorbing hydrophobic or weakly polar mycotoxins such as zearalenone (ZEN) and ochratoxin. Therefore, this study was undertaken to assess the impact of MDA inclusion in mycotoxin-contaminated diets on performance and rumen fermentation variables in lambs. The results indicated that MDA not only significantly improved the growth performance and nutrient digestibility of Hu lambs but also enhanced the molar proportion of propionate and ammonia concentration, and reduced the acetate to propionate ratio and the molar proportion of n-butyrate.

Construction of Quasi-Ordered Metal-Organic Frameworks Superstructures via Colloidal Assembly of Anisotropic Particles for Selective Organic Vapor Sensing.

Colloidal assembly of anisotropic particles holds great promise for achieving diverse packing geometries and unique photonic properties. One intriguing candidate for anisotropic self-assembly is colloidal metal-organic frameworks (MOFs), which possess remarkable characteristics including substantial surface areas, tunable chemical properties, a wide range of structural variations, and diverse polyhedral shapes. In this study, the colloidal assembly of nearly spherical and polyhedral MOFs particles to form quasi-ordered photonic superstructures was investigated. Specifically, monodisperse near-spherical ZIF-8 (NSZIF-8) and rhombic dodecahedron ZIF-8 (RDZIF-8) colloidal nanoparticles were synthesized as the fundamental building blocks. These nanoparticles are employed to construct MOFs-based self-assembled superstructures that exhibit thin-film interference optical properties. Importantly, these superstructures demonstrate exceptional responsiveness to gaseous homologues and isomers with approximate refractive indices. The dynamic reflection spectral patterns exhibited by these superstructures provide valuable insights into the diffusion rates and surface tension characteristics of the target solvents. These findings underscore the potential of MOFs-based superstructure thin films to discriminate between physiochemically similar solvents, opening new avenues for applications in various fields.

Regulating the Electronic Structure of Ni Sites in Ni(OH)2 by Ce Doping and Cu(OH)2 Coupling to Boost 5-Hydroxymethylfurfural Oxidation Performance.

Biomass is a sustainable and renewable resource that can be converted into valuable chemicals, reducing the demand for fossil energy. 5-Hydroxymethylfurfural (HMF), as an important biomass platform molecule, can be converted to high-value-added 2,5-furandicarboxylic acid (FDCA) via a green and renewable electrocatalytic oxidation route under mild reaction conditions, but efficient electrocatalysts are still lacking. Herein, we rationally fabricate a novel self-supported electrocatalyst of core-shell-structured copper hydroxide nanowires@cerium-doped nickel hydroxide nanosheets composite nanowires on a copper mesh (CuH_NWs@Ce:NiH_NSs/Cu) for electrocatalytically oxidizing HMF to FDCA. The integrated configuration of composite nanowires with rich interstitial spaces between them facilitates fast mass/electron transfer, improved conductivity, and complete exposure of active sites. The doping of Ce ions in nickel hydroxide nanosheets (NiH_NSs) and the coupling of copper hydroxide nanowires (CuH_NWs) regulate the electronic structure of the Ni active sites and optimize the adsorption strength of the active sites to the reactant, meanwhile promoting the generation of strong oxidation agents of Ni3+ species, thereby resulting in improved electrocatalytic activity. Consequently, the optimal CuH_NWs@Ce:NiH_NSs/Cu electrocatalyst is able to achieve a HMF conversion of 98.5% with a FDCA yield of 97.9% and a Faradaic efficiency of 98.0% at a low constant potential of 1.45 V versus reversible hydrogen electrode. Meanwhile, no activity attenuation can be found after 15 successive cycling tests. Such electrocatalytic performance suppresses most of the reported Cu-based and Ni-based electrocatalysts. This work highlights the importance of structure and doping engineering strategies for the rational fabrication of high-performance electrocatalysts for biomass upgrading.

Hierarchical Nickel-Cobalt Hydroxide Composite Nanosheets-Incorporated Nitrogen-Doped Carbon Nanotubes Embedded with Nickel-Cobalt Alloy Nanoparticles for Driving a 2 V Asymmetric Supercapacitor.

A class of electrode materials with favorable structures and compositions and powerful electrochemical (EC) properties are needed to boost the supercapacitor capacity significantly. In this study, an inventive technique was established to produce a well-aligned nickel-cobalt alloy nanoparticles-encapsulated N-doped carbon nanotubes with porous structure and good conductivity on carbon cloth (NiCo@NCNTs/CC) as a substrate. Then, nanosheets of nickel-cobalt layered double hydroxide (NiCo-LDH) were grown on NiCo@NCNTs/CC via a simple EC deposition method to construct a self-supported monolithic hierarchical nanosheets/nanotubes composite electrode of NiCo-LDH/NiCo@NCNTs/CC. In such a composite electrode, the NiCo@NCNTs can act as a good conductor and structural scaffold to grow NiCo-LDH nanosheets with a three-dimensional open and porous structure, which helps to improve the electron/ion-transfer performance, increase the number of exposed reactive sites, and inhibit the aggregation of NiCo-LDH nanosheets, thereby boosting the capacitance and stability. As a positive electrode, the NiCo-LDH/NiCo@NCNTs/CC hierarchical nanosheets/nanotubes electrode displays 1898 mF cm-2 (1262 A g-1) of high capacitance, long-term stability with a capacitance retention of around 100% after 8000 cycles, and nearly 103% Coulombic efficiency. After assembling into an asymmetric supercapacitor with a Co(OH)2/NiCo@NCNTs/CC negative electrode, 2 V of operating voltage with 73.1 µW h cm-2 (52.8 W h kg-1) of energy density was achieved. Our investigation gives a potential approach for constructing the integrated composite electrode of transition-metal compounds-carbon materials for high-performance supercapacitors.

Synergy of Platinum Single Atoms and Platinum Atomic Clusters on Sulfur-Doped Titanium Nitride Nanotubes for Enhanced Hydrogen Evolution Reaction.

Highly dispersed Pt, such as Pt single atoms and atomic clusters, has great potential in the electrocatalytic hydrogen evolution reaction (HER) due to the high atomic efficiency and unique electronic configuration. Rationally regrating the electronic structure of Pt catalysts is desirable for promoting the HER performance. Herein, a 3D self-supported monolithic electrode consisting of Pt single atoms (PtSAs ) and Pt atomic clusters (PtACs ) anchored on sulfur-doped titanium nitride nanotubes (S-TiN NTs) encapsulated in polyaniline (PANI) on Ti mesh (PANI@Pt/S-TiN NTs/Ti) via a facile electrochemical strategy for efficient HER is designed and synthesized. Contributed by the unique structure and composition and the synergy of PtSAs , PtACs and S-TiN NTs, the PANI@Pt/S-TiN NTs/Ti electrode exhibits ultrahigh HER activities with only 12, 25 and 39 mV overpotentials at -10 mA cm-2 in acidic, alkaline and neutral media, respectively, and can maintain a stable performance for 25 h. Impressively, the mass activities are respectively up to 26.1, 22.4, and 17.7 times as that of Pt/C/CC electrode. Theoretical calculation results show that the synergistic effect of PtSAs , PtACs , and S-TiN NTs can optimize the electronic structure of Pt and generate multiple active sites with a thermodynamically favorable hydrogen adsorption free energy (ΔGH* ), thereby resulting in an enhanced HER activity.

Rational Design of Porous Nanowall Arrays of Ultrafine Co4N Nanoparticles Confined in a La2O2CN2 Matrix on Carbon Cloth for a High-Performing Supercapacitor Electrode.

Transition metal nitrides (TMNs) have received special concern as important energy storage materials, owing to their high conductibility, good mechanical strength, and superior corrosion resistance. However, their insufficient capacitance and poor cycling stability limit their practical applications for supercapacitors. Here, a novel three-dimensional (3D) self-supported integrated electrode consisted of porous nanowall arrays of ultrafine cobalt nitride (Co4N) nanoparticles encapsulated in a lanthanum oxycyanamide (LOC) matrix on carbon cloth (Co4N@LOC/CC) for outstanding electrochemical energy storage is rationally designed and fabricated. The 3D monolithic configuration of porous nanowall arrays facilitates the mass/charge transfer, the exposure of electroactive sites, and the enhancement of electrical conductivity. Meanwhile, the unique core-shell structure of Co4N@LOC can prevent ultrafine Co4N nanoparticles from sintering, agglomeration, and oxidation and promotes electron transfer dynamics during the redox reaction, meanwhile enhancing the stability of the electrode. Additionally, the synergy of Co4N and LOC can result in an efficient electron/ion transport in the process of the charge-discharge. Because of these features, the Co4N@LOC/CC electrode displays superior specific capacitance (895.6 mF cm-2 or 613.4 F g-1 at 1 mA cm-2) and admirable cycling durability (87.9% capacitance reservation after 10 000 cycles), surpassing the majority of nitride-based electrodes reported thus far. Furthermore, after being assembled into an asymmetric supercapacitor using active carbon (AC) as an anode, the obtained Co4N@LOC/CC//AC/CC device displays a high energy density of 41.7 Wh kg-1 at the power density of 875.8 W kg-1 with a high capacitance reservation of 87.6% after 5000 cycles at 2 mA cm-2. This work offers an efficient approach of combining TMNs with rare earth compounds to enhance the capacitance and stability of TMNs for supercapacitor electrodes.

Formation of Interfacial Cu-[OX ]-Ce Structures with Oxygen Vacancies for Enhanced Electrocatalytic Nitrogen Reduction.

Electrochemical nitrogen reduction powered by renewable electricity is a promising strategy to produce ammonia. However, the lack of efficient yet cheap electrocatalysts remains the biggest challenge. Herein, hybrid Cu2 O-CeO2 -C nanorods are prepared on copper mesh through a metal-organic framework template route. The Cu-loaded Ce-MOF is thermally converted to Cu2 O-CeO2 heterojunctions with interfacial Cu-[OX ]-Ce structures embedded in carbon. Theoretical calculations reveal the lower formation energy of oxygen vacancies in Cu-[OX ]-Ce structures than in the Cu2 O or CeO2 phase. The Cu-[OX ]-Ce structures with oxygen vacancies enable the formation of interfacial electron-rich Cu(I) species which show significantly enhanced performance toward electrocatalytic nitrogen reduction with an NH3 yield of 6.37 × 10-3  µg s-1 cm-2 and a Faradaic efficiency of 18.21% in 0.10 m KOH at -0.3 V versus reversible hydrogen electrode. This work highlights the importance of modulation of charge distribution of Cu-based electrocatalysts to boost the activity toward nitrogen reduction.

Boosting Nitrogen Reduction Reaction via Electronic Coupling of Atomically Dispersed Bismuth with Titanium Nitride Nanorods.

Electrocatalytic nitrogen reduction reaction (NRR) is a promising alternative to the traditional Haber-Bosch process. However, the sluggish kinetics and competitive hydrogen evolution reaction result in poor NH3 yield and low Faradaic efficiency (FE). Herein, single bismuth atoms incorporated hollow titanium nitride nanorods encapsulated in nitrogen-doped carbon layer (NC) supported on carbon cloth (NC/Bi SAs/TiN/CC) is constructed for electrocatalytic NRR. Impressively, as an integrated electrode, it exhibits a superior ammonia yield rate of 76.15 µg mgcat -1 h-1 (9859 µg µmolBi -1 h-1 ) at -0.8 V versus RHE and a high FE of 24.60% at -0.5 V versus RHE in 0.1 m Na2 SO4 solution, which can retain stable performance in 10 h continuous operation, surpassing the overwhelming majority of reported Bi-based NRR catalysts. Coupling various characterizations with theory calculations, it is disclosed that the unique monolithic core-shell configuration with porous structure endows abundant accessible active sites, outstanding charge-transfer property, and good stability, while the cooperation effect of Bi SAs and TiN can simultaneously promote the hydrogenation of N2 into NH3 * on the TiN surface and the desorption of NH3 * to release NH3 on the Bi SA sites. These features result in the significant promotion of NRR performance.

Boosting Hydrogen Evolution Reaction via Electronic Coupling of Cerium Phosphate with Molybdenum Phosphide Nanobelts.

Molybdenum phosphide (MoP) is regarded as one of the most promising alternatives to noble-metal based electrocatalysts for efficient hydrogen evolution reaction (HER) due to its similar d-band electronic structure to noble metals and tunable features associated with phase and composition. However, it still remains a great challenge to construct MoP electrocatalysts with abundant active sites that possess ideal H binding strength to promote catalytic performance. In this work, it is found that by anchoring a rare earth compound, cerium phosphate (CePO4 ) on MoP (CePO4 /MoP), the stabilized Ce3+ in CePO4 can significantly boost the formation of oxygen vacancies in ceria (CeO2 ) in situ formed on CePO4 surface during HER, which effectively regulates the d-band electronic density-of-states of MoP, increases the numbers of active sites, and promotes the vectorial electron transfer, therefore greatly enhancing the HER performance of MoP. The optimized CePO4 /MoP/carbon cloth (CC) electrocatalyst exhibits a significantly improved HER performance with an overpotential of 48 mV at 10 mA cm-2 and a Tafel slope of 38 mV dec-1 , about two times better than the HER performance of MoP catalyst without CePO4 (with an overpotential >80 mV dec-1 at 10 mA cm-2 ), very close to commercial Pt/C catalyst.

Multi-Elemental Electronic Coupling for Enhanced Hydrogen Generation.

A robust polyaniline-assisted strategy is developed to construct a self-supported electrode constituting a nitrogen, phosphorus, sulfur tri-doped thin graphitic carbon layer encapsulated sulfur-doped molybdenum phosphide nanosheet array (NPSCL@S-MoP NSs/CC) with accessible nanopores, desirable chemical compositions, and stable composite structure for efficient hydrogen evolution reaction (HER). The multiple electronic coupling effects of S-MoP with N, P, S tri-dopants afford effective regulation on their electrocatalytic performance by endowing abundant accessible active sites, outstanding charge-transfer property, and d-band center downshift with a thermodynamically favorable hydrogen adsorption free energy (ΔGH* ) for efficient hydrogen evolution catalysis. As a result, the NPSCL@S-MoP NSs/CC electrode exhibits overpotentials as low as 65, 114, and 49 mV at a geometric current density of 10 mA cm-2 and small Tafel slopes of 49.5, 69.3, and 53.8 mV dec-1 in 0.5 m H2 SO4 , 1.0 m PBS, and 1.0 m KOH, respectively, which could maintain 50 h of stable performance, almost outperforming all MoP-based catalysts reported so far. This study provides a valuable methodology to produce interacted multi-heteroatomic doped graphitic carbon-transition metal phosphide electrocatalysts with superior HER performance in a wide pH range.

Ultrafine CoP/Co2P Nanorods Encapsulated in Janus/Twins-type Honeycomb 3D Nitrogen-Doped Carbon Nanosheets for Efficient Hydrogen Evolution.

In this study, we report a Janus- or twins-type honeycomb 3D porous nitrogen-doped carbon (NC) nanosheet array encapsulating ultrafine CoP/Co2P nanorods supported on Ti foil (CoP/Co2P@NC/Ti) as a self-supported electrode for efficient hydrogen evolution. The synthesis and formation mechanism of 3D porous NC nanosheet array assembled into a honeycomb layer with ultrafine CoP/Co2P single-crystal nanorods encapsulated is systematically presented. The CoP/Co2P@NC/Ti electrode exhibits low overpotentials (η10) of 31, 49, and 64 mV at a current density of -10 mA cm-2 in 0.5 M H2SO4, 1.0 KOH, and 1.0 M PBS, respectively, exceeding the overwhelming majority of the documented transition metal phosphide-based electrocatalysts. Density functional theory calculation reveals that the superior electrocatalytic performance for hydrogen evolution reaction could be ascribed to the strong coupling effects of the reactive facets of CoP and Co2P with the 3D porous NC nanosheet, making it exhibit a more thermo-neutral hydrogen adsorption free energy.

A dendritic core-shell Cu@PtCu alloy electrocatalyst resulting in an enhanced electron transfer ability and boosted surface active sites for an improved methanol oxidation reaction.

We reported the design of a core-shell Cu@PtCu electrocatalyst consisting of dendritic PtCu alloy branches assembling on Cu core nanocrystals. The Cu@PtCu electrocatalyst shows superior electrocatalytic performance toward a methanol oxidation reaction. Its specific activity and mass activity can reach 3.56 mA cm-2 and 1568 mA mgPt-1, which are 4.8 and 7.1 times higher than those of a commercial 20% Pt/C catalyst.

Graphene Decorated with Uniform Ultrathin (CoP)x -(FeP)1-x Nanorods: A Robust Non-Noble-Metal Catalyst for Hydrogen Evolution.

Developing high-performance but low-cost hydrogen evolution reaction (HER) electrocatalysts with superior activity and stability for future sustainable energy conversion technologies is highly desired. Tuning of microstructure, configuration, and chemical composition are paramount to developing effective non-noble electrocatalysts for HER. Herein, a universal "nanocasting" method is reported to construct graphene decorated with uniform ternary (CoP)x -(FeP)1-x (0 ≤ x ≤ 1) nanorods hybrids with different chemical compositions [(CoP)x -(FeP)1-x -NRs/G] as a highly active and durable nonprecious-metal electrocatalyst for the HER. The optimized (CoP)0.54 -(FeP)0.46 -NRs/G electrocatalyst exhibits overpotentials of as low as 57 and 97 mV at 10 mA cm-2 , Tafel slopes of 52 and 62 mV dec-1 , exchange current densities of 0.489 and 0.454 mA cm-2 , and Faradaic efficiency of nearly 100% in acidic and alkaline media, respectively. More importantly, this electrocatalyst also exhibits high tolerance and durability in a wide pH range and keeps catalytic activity for at least 3000 cycles and 24 h of sustained hydrogen production. The excellent catalytic performance of the (CoP)x -(FeP)1-x -NRs/G electrocatalyst may be ascribed to its unique mesoporous structure and strong synergistic effect between CoP and FeP. Thus, the work provides a feasible way to fabricate cheap and highly efficient electrocatalyst as alternatives for Pt-based electrocatalysts for HER in electrochemical water splitting.

A General Method for Constructing Two-Dimensional Layered Mesoporous Mono- and Binary-Transition-Metal Nitride/Graphene as an Ultra-Efficient Support to Enhance Its Catalytic Activity and Durability for Electrocatalytic Application.

We constructed a series of two-dimensional (2D) layered mesoporous mono- and binary-transition-metal nitride/graphene nanocomposites (TMN/G, TM = Ti, Cr, W, Mo, TiCr, TiW, and TiMo) via an efficient and versatile nanocasting strategy for the first time. The 2D layered mesoporous TMN/G is constituted of small TMN nanoparticles composited with graphene nanosheets and has a large surface area with high porosity. Through decoration with well-dispersed Pt nanoparticles, 2D layered mesoporous Pt/TMN/G catalysts can be obtained that display excellent catalytic activity and stability for methanol electro-oxidation reactions (MOR) and oxygen reduction reactions (ORR) in both acidic and alkaline media. The 2D layered mesoporous binary-Pt/TMN/G catalysts possess catalytic activity superior to that of mono-Pt/TMN/G, graphene free Pt/TMN, Pt/G, and Pt/C catalysts. Encouragingly, the 2D layered mesoporous Pt/Ti0.5Cr0.5N/G catalyst exhibits the best electrocatalytic performance for both MOR and ORR. The outstanding electrocatalytic performance of the Pt/Ti0.5Cr0.5N/G catalyst is rooted in its large surface area, high porosity, strong interaction among Pt, Ti0.5Cr0.5N, and graphene, an excellent electron transfer property facilitated by N-doped graphene, and the small size of Pt and Ti0.5Cr0.5N nanocrystals. The outstanding catalytic performance provides the 2D layered mesoporous Pt/Ti0.5Cr0.5N/G catalyst with a wide range of application prospects in direct methanol fuel cells in both acidic and alkaline media. The synthetic method may be available for constructing other 2D layered mesoporous metal nitrides, carbides, and phosphides.

Universal Strategy to Fabricate a Two-Dimensional Layered Mesoporous Mo2C Electrocatalyst Hybridized on Graphene Sheets with High Activity and Durability for Hydrogen Generation.

A universal strategy was developed for fabrication of a highly active and durable precious-metal-free mesoporous Mo2C/graphene (m-Mo2C/G) electrocatalyst with a two-dimensional layered structural feature via a nanocasting method using glucose as a carbon source and an in-stiu assembled mesoporous KIT-6/graphene (KIT-6/G) as a template. The m-Mo2C/G catalyst exhibits high catalytic activity and excellent durability for hydrogen evolution reaction (HER) over a wide pH range, which displays a small onset potential of 8 mV, owerpotential (η10) for driving a cathodic current density of 10 mA·cm(-2) of 135 mV, a Tafel slope of 58 mV·dec(-1), and an exchange current density of 6.31 × 10(-2) mA·cm(-2) in acidic media and an onset potential of of 41 mV, η10 of 128 mV, Tafel slope of 56 mV·dec(-1), and an exchange current density of 4.09 × 10(-2) mA·cm(-2) in alkaline media, respectively. Furthermore, such an m-Mo2C/G electrocatalyst also gives about 100% Faradaic yield and shows excellent durability during 3000 cycles of a long-term test, and the catalytic current remains stable over 20 h at fixed overpotentials, making it a great potential application prospect for energy issues.

A mesoporous "shell-in-shell" structured nanocatalyst with large surface area, enhanced synergy, and improved catalytic performance for Suzuki-Miyaura coupling reaction.

A novel mesoporous "shell-in-shell" structured nanocatalyst (@Pd/meso-TiO2/Pd@meso-SiO2) with large surface area, enhanced synergy, and improved catalytic performance is created for catalyzing Suzuki-Miyaura coupling and 4-nitrophenol reduction reactions.

Architecture engineering toward highly active palladium integrated titanium dioxide yolk-double-shell nanoreactor for catalytic applications.

Rational design of the hierarchical architecture of a material with well controlled functionality is crucially important for improving its properties. In this paper, we present the general strategies for rationally designing and constructing three types of hierarchical Pd integrated TiO2 double-shell architectures, i.e. yolk-double-shell TiO2 architecture (Pd@TiO2/Pd@TiO2) with yolk-type Pd nanoparticles residing inside the central cavity of the hollow TiO2 structure; ultrafine Pd nanoparticles homogenously dispersed on both the external and internal surfaces of the inner TiO2 shell; and double-shell TiO2 architecture (@TiO2/Pd@TiO2) with Pd nanoparticles solely loaded on the external surface of the inner TiO2 shell, and double-shell TiO2 architecture (@TiO2@Pd@TiO2) with Pd nanoparticles dispersed in the interlayer space of double TiO2 shells, via newly developed Pd(2+) ion-diffusion and Pd sol impregnation methodologies. These architectures are well controlled in structure, size, morphology, and configuration with Pd nanoparticles existing in various locations. Owing to the variable synergistic effects arising from the location discrepancies of Pd nanoparticle in the architectures, they exhibit remarkable variations in catalytic activity. In particular, different from previously reported yolk-shell structures, the obtained yolk-double-shell Pd@TiO2/Pd@TiO2 architecture, which is revealed for the first time, possesses a uniform hierarchical structure, narrow size distribution, and good monodispersibility, and it creates two Pd-TiO2 interfaces on the external and internal surfaces of the inner TiO2 shell, leading to the strongest synergistic effect of Pd nanoparticles with TiO2 shell. Furthermore, the interlayer chamber between the double TiO2 shells connecting with the central cavity of the hollow TiO2 structure through the mesoporous TiO2 wall forms a nanoreactor for enriching the reactants and preventing the deletion of Pd nanoparticles during the reaction, thus greatly accelerating the reaction speed. Owing to its structural features, yolk-double-shell Pd@TiO2/Pd@TiO2 architecture exhibits extremely high catalytic performance on the Suzuki-Miyaura coupling reaction. The synthetic methodologies are robust for fabricating double-shell architectures with various configurations for applications such as in catalysis, drug delivery, and medicine release. The obtained double-shell architectures may be used as novel catalyst systems with highly efficient catalytic performance for other catalytic reactions.

Ionic liquid assisted chemical strategy to TiO2 hollow nanocube assemblies with surface-fluorination and nitridation and high energy crystal facet exposure for enhanced photocatalysis.

Realization of anionic nonmetal doping and high energy crystal facet exposure in TiO2 photocatalysts has been proven to be an effective approach for significantly improving their photocatalytic performance. A facile strategy of ionic liquid assisted etching chemistry by simply hydrothermally etching hollow TiO2 spheres composed of TiO2 nanoparticles with an ionic liquid of 1-butyl-3-methylimidazolium tetrafluoroborate without any other additives is developed to create highly active anatase TiO2 nanocubes and TiO2 nanocube assemblies. With this one-pot ionic liquid assisted etching process, the surface-fluorination and nitridation and high energy {001} crystal facets exposure can be readily realized simultaneously. Compared with the benchmark materials of P25 and TiO2 nanostructures with other hierarchical architectures of hollow spheres, flaky spheres, and spindles synthesized by hydrothermally etching hollow TiO2 spheres with nonionic liquid of NH4F, the TiO2 nanocubes and TiO2 nanocube assemblies used as efficient photocatalysts show super high photocatalytic activity for degradation of methylene blue, methyl orange, and rhodamine B, due to their surface-fluorination and nitridation and high energy crystal facet exposure. The ionic liquid assisted etching chemistry is facile and robust and may be a general strategy for synthesizing other metal oxides with high energy crystal facets and surface doping for improving photocatalytic activity.

Cytotoxicity of ultrafine monodispersed nanoceria on human gastric cancer cells.

The safety and toxicity of CeO2 nanoparticles (nanoceria) are of growing concern due to their potential applications in biological and medical fields based on the radical scavenging and UV-filtering properties. In this paper, the ultrafine monodisperse (2-5 nm) water-insoluble (CeO2-P) and water-soluble nanoceria modified with various functional groups of dextran (CeO2-dextran), polyacrylic acid (CeO2-PAA) and ethylenediamine (CeO2-EDA) on surface were synthesized via alkaline-based precipitation and inverse microemulsion methods. The cell uptaking, oxidative stress and cytotoxicity of these nanoceria on human gastric cancer cell line (BGC-803) were systematically investigated. It is found that the cell uptaking of nanoceria is largely relied on the function groups on its surfaces and followed the order: CeO2-P > CeO2-EDA > CeO2-dextran > CeO2-PAA. Moreover, the oxidative stress of BGC-803 cells is obviously affected by the antioxidant capacity of nanoceria determined by Ce3+/Ce4+ ratio, which eventually causes the cell viability variable once the nanoceria entered into BGC-803 cells. In addition, the cell viability is also closely correlated with the concentration and surface characteristics of nanoceria. The cytotoxicity of nanoceria on BGC-803 cells is largely dependent on its surface functional groups. Our work may provide guidance on the cytotoxicity of ultrafine monodisperse nanoceria for their uses in biological and medical fields.

Synthesis, phase structure and up-conversion luminescence of NaYF4:Yb3+, Er3+/Tm3+ nanorods.

Upconversion luminescent NaYF4:Yb3+, Er3+/Tm3+ nanocrystals were successfully synthesized via a facile and one-pot solvothermal method using oleic acid/oleylamine (OA/OM) as surfactants. The effects of synthetic parameters including rare earth ion doping concentrations and temperatures on the crystal phase structure, size and shape of NaYF4:Yb3+, Er3+/Tm3+ nanocrystals were systematically investigated. By modulating the synthetic parameters, the shape of NaYF4:Yb3+, Er3+/Tm3+ nanocrystals were controlled in forms of nanorods and nanowires. The reaction temperature has large effects on the phase structure of NaYF4:Yb3+, Er+/Tm3+ nanorods, exhibiting a phase transformation from cubic phase (alpha-) in low temperatures to hexagonal phase (beta-) in high temperatures. Moreover, the upconversion luminescence of NaYF4:Yb3+, Er3+/Tm3+ nanocrystals was found to be dependent on the rare earth ion doping concentrations and temperatures.