An unusual network of α-MnO_(2) nanowires with structure-induced hydrophilicity and conductivity for improved electrocatalysis

Nanowires with anisotropic morphologies have been applied in various scientific and technological areas.It is also widely employed to fabricate nanowires into high-dimensional superstructures(arrays,networks etc.)to overcome the shortcomings of low-dimensional nanowires.However,typical strategies for constructing these superstructures are restricted to complicated and harsh synthetic conditions,not to mention unique 3D structures with advanced properties beyond common superstructures.Herein,we report an unusual network ofα-MnO_(2)nanowires with structure-induced hydrophilicity and conductivity.In the network,the nanowires are interconnected from all directions by nodes,and the 3D network structure is formed from the endless connection of nodes in a node-by-node way.The unique network structure brings about high hydrophilicity and conductivity,both of which are positive factors for an efficient electrocatalyst.Accordingly,the α-MnO_(2) network was tested for electrocatalytic water oxidation and showed significantly enhanced activity compared with isolatedα-MnO_(2)nanowires and 3Dα-MnO_(2)microspheres.This study not only provides a synthetic route toward an advanced network structure but also a new idea for the design of materials for electrochemistry with both efficient mass diffusion and charge transfer.

Comparing electrocatalytic hydrogen and oxygen evolution activities of first-row transition metal complexes with similar coordination environments

Developing cheap and efficient electrocatalysts for water splitting is required for energy conversion techniques.Many first-row transition metal complexes have been shown to be active for the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).Metal ions play crucial roles in these catalytic processes,but the activity dependence on the nature of metal ions has been rarely studied due to the difficulty to compare metal complexes with different coordination environments.We herein reported the synthesis of a series of metal complexes of azido-substituted porphyrin(1),in which metal ions have very similar coordination environments.By grafting 1-M(M=Mn,Fe,Co,Ni,and Cu)onto alkynefunctionalized carbon nanotubes(CNTs)through the same covalent connection,the resulted hybrids 1-M@CNT were all active and robust for both electrocatalytic HER and OER in alkaline aqueous solutions.Among these hybrids,1-Fe@CNT displayed the highest electrocatalytic activity for HER,while 1-Co@CNT was the most active one for OER.Moreover,a two-electrode water electrolysis cell assembled with 1-Fe@CNT as the cathode and 1-Co@CNT as the anode required smaller applied bias potential by210 mV to get 10 mA/cm^(2)current density as compared to that assembled with Pt/C and Ir/C with the same amount of metal loading.This work is significant to correlate HER and OER activity with the nature of first-row transition metal ions and to highlight promising potential applications of molecular electrocatalysis in water splitting.

Engineering nanointerface of molybdenum-based heterostructures to boost the electrocatalytic hydrogen evolution reaction

Rational heterostructure-design in electrocatalysts represents a promising approach toward high performance in the electrocatalytic hydrogen evolution reaction(HER).In specific,optimizing the H adsorption behavior at the surface/interface of heterostructure is of key importance to improve the catalytic performance.Herein,we demonstrate the construction of a heterostructure from a well-defined oxygenbridged Co/Mo heterometallic zeolitic imidazolate framework(MOZ) as an efficient electrocatalyst for HER.The optimized hybrid exhibits high catalytic activity and stability in electrolytes with a wide pH range.Detailed XPS,XAS and theoretical studies reveal that the regulation of metal species can tailor the lattice of Mo_(2)C within the hybrid and induce the formation of defect sites,which could not only induce surface charge transfer between the atoms and provide an additional active site,but also affect the H adsorption behavior at the interface of a heterostructure.This work provides an effective strategy to design a heterostructure with tailored active sites for energy conversion.

Coprecipitation Synthesis of Fluorides Nanoparticles with Multiform Structures and Mechanisms Research

Fluoride nanoparticles with multiform crystal structures and morphologies were successfully synthesized by a facile, effective, and environmentally friendly coprecipitation method. Transmission electron microscopy (TEM) was used to characterize the nanoparticles. The nanoparticles were modified by PEI, CTAB, PAA and Ci, respectively. It was feasible for function by -COOH and -NH2 groups, due to the surface modification. Moreover, different surface modifications of the nanoparticles were examined. The possible formation mechanisms for fluoride nanoparticles with surface modification were presented in detail. More importantly, it is expected to be widely applied to biomedicine.

Inherent mass transfer engineering of a Co,N co-doped carbon material towards oxygen reduction reaction

Oxygen reduction reaction (ORR) is an important process for the conversion and utilization of a wide range of renewable energy sources, and is critical for the shape of future energy scenario [1–10]. However, ORR is a complex four-electron transfer process and is kinetically sluggish. It is urgent to develop high-efficient electrocatalysts to solve this problem [11–15]. Up to now, precious metal-based catalysts such as Pt-based electrocatalysts have been widely studied and found to be one of the most efficient electrocatalysts for ORR. However, the high price and the small reserves limit their large-scale commercialization [10,16–23]. Therefore, in order to fulfill needs for the practical applications, it is necessary to develop low-cost electrocatalysts, also with high activity and great stability [19,24–28].

Electrochemically Generated Iodine Cations from a Glassy Carbon Electrode for Highly Selective Iodination of Anisole

The synthesis of aryl iodides from commercially available raw chemicals by simple,cheap and green strategies is of fundamental signifi cance.Aryl iodides can undergo a series of homo-/cross-coupling reactions for the synthesis of important industrial chemicals and materials.Traditional methods require the electrophilic substitution on aromatic compounds by iodine or hypervalent iodine compounds,which suff ers from the use of erosive halogens or hazardous oxidants.With the development of green chemistry in the fi eld of electrochemical synthesis,anodic oxidation-derived I^(+)cations have been used for substitution reactions.However,the selectivity of the iodination by these electrochemical methods remains unsatisfactory.We believed that the anolyte is contaminated by trace platinum species from the working electrode.Herein,we report the generation of active I^(+)species from the anodic oxidation of I_(2) in acetonitrile using a glassy carbon electrode.With the presence of H^(+),electrolyte prepared with a glassy carbon anode can react with anisole to selectively form 4-iodoanisole with a yield as high as 97%.On contrast,the electrolytes prepared from Pt and graphite anodes fi nished the reaction with yields of 16%and 60%for 4-iodoanisole,respectively.This electrochemical method also applies to the iodination of toluene,benzonitrile and bromobenzene,delivering the target para-iodination products with 92%,84%,and 73%yields,respectively.Thus,an atom-effi cient and highly selective aryl iodination method was developed without the use of excessive oxidants.

Anion Directed Assembly of Cu(Ⅱ)Complexes Formed by a Flexible Ligand

Coordination polymers,consisting of metal,anion and organic ligands,have attracted much attention.The structure of coordination polymers is affected by various factors.To investigate the effects of anion,syntheses and structures of four Cu(II)complexes,namely[(Cu LCl)(PF)](1),[(Cu LCl)(ClO)](2),[(Cu LCl)?CHOH](3)and Cu LCl(4),are reported based on a flexible ligand,1,3-bis(2-pyridylmethyl)imidazolium(L).The ligand is accommodative to kinds of anions,and forms 1-D chains generally upon reaction with Cu(II)salts.The effect is measured by the conformational variation through the dihedral angles between different aromatic rings of the ligand.In order to further investigate the effect of anion,a protonated sample of L,namely,LH(ClO)?HO(5)is also synthesized and structurally characterized,showing an intriguing hydrogen bonded helix.

Synthesis,Crystal Structure and Antineoplasmic Activity of 3,6,8-Tribromo-5-hydroxy-2,7-dimethoxy-2-phenyl-2,3-dihydrochromen-4-one

The reaction of 5-hydroxyl-7-methoxyflavone（tectochrysin） with bromine obtained 3,6,8-tribromo-5-hydroxy-2,7-dimethoxy-2,3-dihydrochromen-4-one（1）, which was characterized by FT-IR, 1 H-NMR, 13C-NMR, elemental analysis and X-ray single-crystal diffraction. Complex 1 belongs to the monoclinic system, space group pbca with a = 9.4673（8）, b = 17.9938（15）, c = 21.2004（17） A, V = 3611.5（5） A3, Z = 8, μ = 0.6726 mm^（-1）, Dc = 1.795 g/cm3, F（000） = 2080, the final R = 0.0358 and wR = 0.0644 with I 2σ（I）. The results show that the addition reaction occurs at the carbon-carbon double bond（C2 and C3） of tectochrysin and 1 belongs to dihydroflavone. The reaction mechanism was discussed and the structure revealed that the crystal structure of 1 is stabilized by intramolecular hydrogen bonds and C–Br···π interactions. The antitumor ability of 1 was evaluated against human leukemia cells（K562）, human breast cancer cells（MCF-7） and human lung cancer cells（A549）. 1 exhibited potent antitumor activities against human leukemia cells（K562） with the IC50 values of 18.9 μmol/L.

A High-Precision Calculation of Bond Length and Spectroscopic Constants of Hg2 Based on the Coupled-Cluster Theory with Spin-Orbit Coupling

Based on the two-component relativistic effective core potential and matched basis sets cc-pwcvnz-pp （n=Q, 5）, combining the completed basis-set extrapolation of electronic correlation energy and the fourth-order polynomial fitting technique, the bond length and spectroscopic constants of Hg2 are studied by the coupled cluster theory with spin-orbit coupling. Spin-orbit coupling is included in the post Hartree-Fock procedure, i.e., in the coupled- cluster iteration, to obtain more reliable theoretical results. The results show that our theoretical values agree with the experimental values very well and will be helpful to understand the spectral character of Hg2.

Synthesis,Crystal Structure and Neuroprotection of a Novel Isoflavone Sulfonamide Compound

4＂,7-Dimethoxy-N-methylisoflavone-3＂-sulfonamide （3） was synthesized by a two step synthesis method and characterized via IR and 1H NMR. Its chemical structure was determined by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group C2/c with a = 27.677（13）, b= 10.490（5）, c = 13.982（7） A, β = 118.781 （9）°, V = 3558（3） A3, Z = 8, F（000） = 1568, Dc = 1.401 Mg/m3, Mr = 375.39,/t = 0.217 mm-1, 2 = 0.71073 A, the final R = 0.0436 and wR = 0.0910 for 3168 observed reflections with 1〉 2δ（/）. The compound was studied subsequently for the potent neuroprotective activity, and showed effects against oxygen-glucose deprivation injury in PC12 cells in a dose-dependent manner （protection： 42.5% at 100 μg-mL-1, 35.1% at 10 μg-mL-1 and 22.5% at 1 μg·mL-1）.

Crystal Structure and ESIPT Phenomena of Anionic 2H-Phenanthro[9,10-c]pyrazol-11-ols

Using 4＇-methoxy-5-hydroxyisoflavone and 4＇,5-dihydroxy-7-methoxyisoflavone as leding compounds,6-methoxy-2 H-phenanthro[9,10-c]pyrazol-11-ol（1 a） and 9-methoxy-2 Hphenanthro [9,10-c]pyrazol-6,11-diol（1 b） were synthesized by two dehydration processes in the EtOH solution.They were characterized by IR,^1H NMR and ^13C NMR.The black prism crystal of 1 a was grown by the slow solvent evaporation technique from 40：1（v/v） CHCl3/MeOH,and it was determined by single-crystal X-ray diffraction.In the crystal structure,1 a was stabilized by intramolecular（O–H···N） and intermolecular（N–H···O,O–H···O,π···π,C–H···π） interactions.In addition,the fluorescence properties of 1 a and 1 b in the base and neutral media revealed that they possessed excited state intramolecular proton transfer phenomena（ESIPT）.

Synthesis,Crystal Structure and Antitumor Activity of Tectochrysin-6-sulfonate

In order to enhance water-solubility and biological utilization rate of tectochrysin,sodium 5-hydroxyl-7-methoxyflavone-6-sulfonate（1） was synthesized and its structure was identified on the basis of ^1 H NMR,FT-IR and elemental analysis.5-Hydroxyl-7-methoxyflavone-6-sulfonate was assembled with Ni（II） or Mn（II）,hexaquanickel（II） bis（5-hydroxyl-7-methoxyflavone-6-sulfonate） tetrahydrate（2） and hexaquamanganese（II） bis（5-hydroxyl-7-methoxyflavone-6-sulfonate） tetrahydrate（3） were obtained and characterized by IR spectroscopy.The crystal structures of 2 and 3 were determined by X-ray single-crystal diffraction analysis.The results showed that 2 and 3 are isomorphous crystals and crystallize in monoclinic crystal system,space group C2/c.In 2 and 3,the supramolecular structures are organized into hydrophilic and hydrophobic regions.Hydrophilic regions are generated by O–H？？？O hydrogen bonds among sulfonate groups,latticed water molecules and coordinated water molecules.The π-π stacking interactions assemble the flavone skeletons into columns and these columns form hydrophobic regions.The sulfonate groups play an important role as a bridge of the hydrophilic and hydrophobic regions as well as the inorganic and organic components.Three-dimensional networks of 2 and 3 are furnished by extensive array of hydrogen bonds,π-π stacking interactions and electrostatic interactions.The anti-proliferative activities of 1-3 in vitro against human leukemia cells K562 and human lung cancer cells A549 were evaluated by the standard MTT assay.The pharmacological activity results showed that the introduction of sulfonic acid groups enhanced the antitumor activity of tectochrysin.

Heterostructural NiFeW disulfide and hydroxide dual‐trimetallic core‐shell nanosheets for synergistically effective water oxidatio

A stable and highly active core‐shell heterostructure electrocatalyst is essential for catalyzing oxygen evolution reaction(OER).Here,a dual‐trimetallic core‐shell heterostructure OER electrocatalyst that consists of a NiFeWS_(2) inner core and an amorphous NiFeW(OH)_(z)outer shell is designed and synthesized using in situ electrochemical tuning.The electrochemical measurements of different as‐synthesized catalysts with a similar mass loading suggest that the core‐shell Ni_(0.66)Fe_(0.17)W_(0.17)S_(2)@amorphous NiFeW(OH)_(z) nanosheets exhibit the highest overall performance compared with that of other bimetallic reference catalysts for the OER.Additionally,the nanosheet arrays were in situ grown on hydrophilic‐treated carbon paper to fabricate an integrated three‐dimensional electrode that affords a current density of 10 mA cm^(−2) at a small overpotential of 182 mV and a low Tafel slope of 35 mV decade^(−1) in basic media.The Faradaic efficiency of core‐shell Ni_(0.66)Fe_(0.17)W_(0.17)S_(2)@amorphous NiFeW(OH)_(z) is as high as 99.5% for OER.The scanning electron microscope,transmission electron microscope,and X‐ray photoelectron spectroscopy analyses confirm that this electrode has excellent stability in morphology and elementary composition after long‐term electrochemical measurements.Importantly,density functional theory calculations further indicate that the core‐shell heterojunction increased the conductivity of the catalyst,optimized the adsorption energy of the OER intermediates,and improved the OER activity.This study provides a universal strategy for designing more active core‐shell structure electrocatalysts based on the rule of coordinated regulation between electronic transport and active sites.

Chemical Synthesis of Globo H and Mannobiose Glycopolymers and their Immunological Stimulation

Tumor-associated carbohydrate antigens(TACAs)provide a special class of tumor-specific antigens that show promising applications in cancer immunotherapy.However,the weak immunogenicity and structural complexity of TACAs are obstacles to their clinical application.Here,based on a fast and low-cost purification strategy for oligosaccharide synthesis,the synthesis of tumour-associated carbohydrate antigens Globo H and mannobiose which resembles repeat unit of mannan was achieved.To enhance the immunogenicity and multivalent effect,Globo H and mannobiose were covalently attached to degradable polymer backbones.2D spindle-like lamellar micelle and globular micelle were obtained from glycopolymer through a solvent-exchange method of self-assembly.The glyconanoparticle showed good biocompatibility and degradability.Immunological functions of these glyconanoparticles such as stimulation of BMDC to cause upregulation of inflammatory factors were preliminarily explored.

Fabrication of TiO_2(B)/anatase heterophase junctions in nanowires via a surface-preferred phase transformation process for enhanced photocatalytic activity

Heterojunction fabrication is one of the most effective strategies for enhancing the photocatalytic performance of semiconductor photocatalysts. Here, TiO2（B）/anatase nanowires with interfacial heterostructures were prepared through a three-step synthesis method, including hydrothermal treatment, H＋ exchange, and annealing. The phase structures of the nanowires in the bulk and on the surface during the annealing process were monitored by XRD and UV-Raman spectroscopy, respectively. SEM and TEM results indicate that the TiO2（B） nanowires partially collapse and transform into anatase during the annealing process and the heterophase junction structure is formed simultaneously. On the basis of the phase structure together with morphology data, a phase-transformation mechanism was proposed. Photocatalytic activity was evaluated by hydrogen production and pollutant-degradation assays. The optimized structure of the photocatalyst contains 24% TiO2（B） in the bulk and 100% anatase on the surface. The charge-carrier behavior during the photocatalytic process was investigated by photocurrent, electrochemical impedance spectroscopy（EIS）, and photoluminescence（PL） spectroscopy, which revealed that the heterophase-junction structure in the bulk was responsible for the highly efficient charge separation and transportation, etc.; the anatase on the surface took control of the high surface-reaction activity.

Direct growth of holey Fe3O4-coupled Ni(OH)2 sheets on nickel foam for the oxygen evolution reaction

The oxygen evolution reaction(OER)is a half-reaction of water electrolysis,and the OER performance of an electrocatalyst is significantly related to its energy conversion efficiency.Due to their high OER activity,transition metal-based nanomaterials have become potential low-cost substitutes for Ir/Ru-based OER electrocatalysts in an alkaline environment.Herein,holey Fe3O4-coupled Ni(OH)2 sheets(Ni(OH)2-Fe H-STs)were easily achieved by a simple mixed-cyanogel hydrolysis strategy.The two-dimensional(2D)Ni(OH)2-Fe H-STs with ca.1 nm thickness have a high specific surface area,abundant unsaturated coordination atoms,and numerous pores,which are highly favorable for electrocatalytic reactions.Meanwhile,the introduction of Fe improves the conductivity and regulates the electronic structure of Ni.Due to their special structural features and synergistic effect between the Fe and Ni atoms,Ni(OH)2-Fe H-STs with an optimal Ni/Fe ratio show excellent OER activity in a 1 M KOH solution,which significantly exceeds that of the commercial RuO2 nanoparticle electrocatalyst.Furthermore,Ni(OH)2-Fe H-STs can be grown on nickel foam(NF),and the resulting material exhibits enhanced OER activity,such as a small overpotential of 200 mV and a small Tafel slope of 56 mV dec−1,than that of Ni(OH)2-Fe H-STs without NF.

Cobalt porphyrins supported on carbon nanotubes as model catalysts of metal-N_(4)/C sites for oxygen electrocatalysis

Transition-metal based M-N_4/C catalysts are appealing for electrocatalytic oxygen reduction reaction(ORR) and oxygen evolution reaction(OER). Employing model catalysts, which have well-defined molecular structures and coordination environments, to investigate electrocatalytic performance of M-N_4/C sites for ORR and OER is of fundamental significance. Herein, we reported the use of Co tetra(phenyl)porphyrin 1 and Co tetra(pentafluorophenyl)porphyrin 2 as models to probe the role of Co-N_4/C sites for oxygen electrocatalysis. We showed that Co porphyrin 1 is more efficient than its structural analogue 2 for oxygen electrocatalysis in alkaline aqueous solutions, indicating that the electronrich Co-N_4/C site is more favored when noncovalently adsorbed on carbon supports. This work inspires rational design of reaction-oriented catalysts for sustainable energy storage and conversion technologies.

Highly active CoP-CO_(2)N confined in nanocarbon enabling efficient electrocatalytic immobilizing-conversion of polysulfide targeting high-rate lithium-sulfur batteries

Lithium-sulfur batteries suffer from poor cycling stability because of the intrinsic shuttling effect of intermediate polysulfides and sluggish reaction kinetics,especially at high rates and high sulfur loading.Herein,we report the construction of a CoP-CO_(2)N@N-doped carbon polyhedron uniformly anchored on three-dimensional carbon nanotubes/graphene(CoP-CO_(2)N@NC/CG)scaffold as a sulfur reservoir to achieve the trapping-diffusion-conversion of polysulfides.Highly active CoP-CO_(2)N shows marvelous catalytic effects by effectively accelerating the reduction of sulfur and the oxidation of Li_(2)S during the discharging and charging process,respectively,while the conductive NC/CG network with massive mesoporous channels ensures fast and continuous long-distance electron/ion transportation.DFT calculations demonstrate that the CoP-CO_(2)N with excellent intrinsic conductivity serves as job-synergistic immobilizing-conversion sites for polysulfides through the formation of P…Li/N…Li and Co…S bonds.As a result,the S@CoP-CO_(2)N@NC/CG cathode(sulfur content 1.7 mg cm^(-2))exhibits a high capacity of988 mAh g^(-1)at 2 C after 500 cycles,which is superior to most of the electrochemical performance reported.Even under high sulfur content(4.3 mg cm^(-2)),it also shows excellent cyclability with high capacity at 1 C.

Core-branch Co Ni hydroxysulfides with versatilely regulated electronic and surface structures for superior oxygen evolution electrocatalysis

To satisfy the rapid development of gas-involving electrocatalysis(O2, CO2, N2, etc.), nanostructured electrocatalysts with favorably regulated electronic structure and surface nanostructures are urgently required. Herein, we highlighted a core-branch hydroxysulfide as a significantly enhanced oxygen evolution reaction electrocatalyst. This hydroxysulfide was facilely fabricated via a versatile interfacial reaction in S2- inorganic solution at room temperature for a designed period. The moderative growth kinetics contributed to the growth of interconnected hydroxysulfide nanosheets with high-sulfur contents on the hydroxide precursor substrates, resulting in a hierarchical nanostructure with multifunctional modifications, including regulated electronic structure, rapid electron highway, excellent accessibility, and facilitated mass transfer. Such synthetic methodology can be generalized and facilely governed by regulating the temperature, concentration, duration, and solvent for targeted nanostructures. Contributed to the favorably regulated electronic structure and surface nanostructure, the as-obtained core-branch Co2NiS2.4(OH)1.2 sample exhibits superior OER performance, with a remarkably low overpotential(279 m V required for 10.0 m A c^m-2), a low Tafel slope(52 m V dec^-1), and a favorable long-term stability. This work not only presents a promising nanostructured hydroxysulfide for excellent OER electrocatalysis, but also shed fresh lights on the further rational development of efficient electrocatalysts.

Role of the Cu-ZrO_(2) interface in the hydrogenation of levulinic acid to γ-valerolactone

Here we exquisitely fabricated Cu/ZrO_(2)-dp catalysts with plentiful Cu-ZrO_(2)interfaces by depositing amorphous ZrO_(2)onto Cu nanoparticles for the hydrogenation of levulinic acid(LA)to y-valerolactone(GVL).With the created plentiful CU-ZrO_(2)interfaces,the optimal catalyst 3 Cu/ZrO_(2)-dp exhibited exceptional catalytic performance under mild reaction conditions,and achieved the highest GVL mass productivity of 266.0 mmol GVL·h^(-1)·g^(-1)Cu,which was 12.5 and 2.3 times of CU/ZrO_(2)catalysts with equivalent Cu loadings prepared by traditional impregnation(3 Cu/ZrO_(2)-im)or co-precipitation(3 Cu/ZrO_(2)-cp).As far as we know,this GVL mass productivity stood at the highest level compared with those obtained using non-noble metal catalysts under similar reaction conditions.By systematic investigation with multiple characterizations,density functional theory(DFT)calculations,and kinetic studies,it was found that interfacial active centers were created at Cu-ZrO_(2)interfaces,which contained oxygen vacancies(O_(v)),negatively charged Cu^(δ)-and partially reduced Zr^(3+)The O_(v) favored the adsorption and activation of LA via its ketone group,while negatively charged Cu^(δ)-was able to enhance heterolysis of H2,which resulted in the formation of H^(+)-Cu^(δ)-and Zr^(3+)-H^(-)active species via hydrogen spillover.Also,plentiful acid sites,which derived from coordinatively unsaturated and defective Zr species,generated at Cu-ZrO_(2)interfaces.With the cooperation of interfacial active centers(Cu^(δ-)-O_(v)-Zr^(3+))and acid sites,the fabricated 3 Cu/ZrO_(2)-dp with plentiful Cu-ZrO_(2)interfaces achieved excellent catalytic performance for the hydrogenation of LA to GVL.Hence,the synergistic catalysis of Cu-ZrO_(2)interfaces provided an effective strategy for designing catalysts with a satisfactory performance for the hydrogenation of LA,which also can be expanded to other hydrodeoxygenation reactions.