Search

The design of efficient photocatalysts is essential for photocatalytic CO2 reduction. With the goal of enhancing efficiency to produce C2+ products, in this study, we synthesized photocatalysts based on an Fe-MOF composited with facet-engineered palladium nanoparticles (Pd NPs). The synthesis involves in situ reduction of palladium on the surface of the Fe-MOF, namely MIL-100(Fe). When assessing the photocatalytic performance, the synthesized catalyst Pd(111)/MIL-100 exhibits a photoelectron utilization efficiency of 21.4% for converting CO2 into C2+ products, surpassing those in the majority of previously reported studies. The results show that MIL-100(Fe) loaded with Pd NPs that exposed the Pd(111) facet is superior for C2+ product selectivity compared with Pd(100)/MIL-100. Density functional theory (DFT) calculations suggest that the difference between Pd(111)/MIL-100 and Pd(100)/MIL-100 may be attributed to the energy barriers required for transition states during the reaction. This study offers an approach for designing photocatalytic catalysts for the CO2 reduction reaction (CO2RR) and generating C2+ products. [ABSTRACT FROM AUTHOR]

Nitrate (NO3−), which exists in both surface water and underground water, is harmful to the environment and human body. Ammonia (NH3) is a kind of necessary produced chemical for industry and daily life. Electrochemical NO3− reduction can eliminate hazardous NO3− and produce value-added NH3 at the same time under ambient conditions but requires efficient catalysts for the NO3− reduction reaction (NO3RR) with high selectivity. Herein, we report on the development of FeS2 nanoparticles on TiO2 nanobelt array (FeS2@TiO2) as an earth-abundant NO3RR electrocatalyst. It shows superior electrocatalytic performance with a large NH3 yield of 860.3 μmol h−1 cm−2 at −0.7 V and a high faradaic efficiency of 97.0% at −0.4 V versus reversible hydrogen electrode in 0.1 M NaOH with 0.1 M NO3−. The theoretical calculations reveal the mechanisms of the enhanced NO3RR performance of FeS2@TiO2. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate (NO3−) reduction has emerged as an attractive dual-function strategy to produce ammonia (NH3) and simultaneously mitigate environmental issues. However, efficient electrocatalysts with high selectivity for NH3 synthesis are highly desired. In this work, we report the Co–NCNT nanohybrid as a highly active electrocatalyst towards NO3−-to-NH3 conversion. In 0.1 M NaOH solution containing 0.1 M NO3−, the Co–NCNT catalyst is capable of attaining a large NH3 yield of 5996 μg h−1 cm−2 and a high faradaic efficiency of 92% at −0.6 V versus reversible hydrogen electrode. Moreover, it displays excellent electrochemical stability. [ABSTRACT FROM AUTHOR]

This work primarily exhibits a systematic study of the large-scale hydrothermal synthesis of β-Mn2V2O7 interconnected nanospheres without templates. An optimal combination of hydrothermal/annealing/atmosphere parameters is identified for the pure phase, which exhibits an excellent cycling performance of 760 mA h g−1 at 0.5 A g−1 over 120 cycles and a rate capability of 470 mA h g−1 at 2 A g−1 as an anode for a lithium ion battery. Guidelines have been provided for the first time for the synthesis of β-Mn2V2O7, which opens broad opportunities for this earth-abundant chemical in electrochemical devices. [ABSTRACT FROM AUTHOR]

The solution processing of macromolecular cellulose material with a high content of incompatible nanomaterial is essential for its functionalization; however, this is still very tricky. Herein, urea is, for the first time, found to enable a simultaneous high filler concentration (56 mg ml−1), long-term stabilization, and the uniform dispersion of universal nanomaterials (i.e., pristine boron nitride nanosheets, graphene nanoplates, and carbon nanotubes) in an aqueous solution of cellulose, based on the tactful utilization of urea's non-covalent chemistry. Its N atom lone pair electrons and O atom empty orbital provide strong non-covalent interactions with nanomaterials, just like a dispersant; at the same time, it also serves as a protective additive for the low-temperature dissolution of cellulose into worm-like nanofibers, offering a volume exclusion effect. More interestingly, this small molecule could be totally removed during the regeneration process of cellulose, without any sacrifice of the composite's characteristics. These miscellaneous functions open up the gate for the green production of high-performance, multifunctional, and high-content regenerated cellulose/nanomaterial composites. [ABSTRACT FROM AUTHOR]

Industrial synthesis of NH3 relies mainly on the traditional Haber–Bosch process, which is highly energy-intensive with enormous greenhouse gas emission. Electrochemical N2 reduction provides an eco-friendly approach for energy-saving NH3 synthesis, but it requires highly efficient electrocatalysts under ambient conditions. In this communication, an MnO2-decorated Ti3C2Tx (T = F, OH) MXene nanohybrid (MnO2–Ti3C2Tx) is proposed as a highly active electrocatalyst for the N2 reduction reaction with strong durability. In addition, only the NH3 product without N2H4 can be detected during the NRR, revealing the excellent selectivity of MnO2–Ti3C2Tx for NH3 formation. A high NH3 yield of 34.12 μg h−1 mgcat−1 and a high faradaic efficiency of 11.39% are achieved at −0.55 V vs. a reversible hydrogen electrode in 0.1 M HCl. Density functional theory calculations further reveal that the unsaturated surface Mn atoms act as active sites to adsorb and activate the inert N2 molecules for the NRR process, and the rate-determining step is the first hydrogenation process. [ABSTRACT FROM AUTHOR]

It is of great importance to search for efficient and stable metal-free catalysts toward electrochemical N2-to-NH3 conversion. In this communication, a chemically oxidized carbon nanotube material (O-CNT) is verified as an active electrocatalyst for the N2 reduction reaction under ambient conditions. In 0.1 M LiClO4, O-CNT achieves a large NH3 yield of 32.33 μg h−1 mgcat.−1 and a high faradaic efficiency of 12.50% at −0.4 V vs. the reversible hydrogen electrode. It also demonstrates superior stability. Density functional theory calculations suggest that C–O groups play a key role in the electrochemical N2 fixation. [ABSTRACT FROM AUTHOR]

Electrocatalytic N2 reduction as an alternative approach to the energy-intensive and large CO2-producing Haber–Bosch process for NH3 synthesis under mild conditions has attracted extensive attention. Current research efforts on N2 reduction have mainly focused on metal-based catalysts, but metal-free alternatives can avoid the issue of metal ion release. In this work, oxygen-doped hollow carbon microtubes (O-KFCNTs) derived from natural kapok fibers are reported as a metal-free NRR electrocatalyst for N2-to-NH3 conversion with excellent selectivity. In 0.1 M HCl, the O-KFCNTs achieve a high faradaic efficiency of 9.1% at −0.80 V vs. a reversible hydrogen electrode (RHE) and a NH3 yield rate of 25.12 μg h−1 mgcat.−1 at −0.85 V vs. RHE under ambient conditions. Notably, this catalyst also demonstrates high stability. [ABSTRACT FROM AUTHOR]

As recently explored lithium-ion battery (LIB) anode materials, transition metal vanadates have attracted much attention due to their excellent electrochemical performance. In this work, we successfully synthesized solid Co3V2O8 microspheres (sCVO MSs) via a facile and controllable hydrothermal reaction, and the magical formation mechanism was also revealed by the different morphologies of sCVO MSs at different reaction times. When tested as LIB anode materials, sCVO MSs showed superior reversible capacities (∼780 mA h g−1 after 250 cycles at 1000 mA g−1 and as high as 550 mA h g−1 even after 400 cycles at 5000 mA g−1) and excellent rate performance (a capacity of ∼500 mA h g−1 at a current density of 2000 mA g−1). It is accordingly demonstrated that uniform sCVO MSs have great potential to be used as high-performance LIB anodes. [ABSTRACT FROM AUTHOR]

Transition metal vanadates have attracted much attention for high capacity anodes of lithium ion batteries (LIBs). However, they have obvious drawbacks (short cycle-lives and low rate performance) because of the intrinsically low electronic conductivity and serious volume variation during Li-ion desorption and insertion. In particular, pure Co3V2O8 micro-pencils (pCVO MPs) have a stable and regular crystal structure, large tap density and uniform grain size, but, unfortunately, they have not exhibited expected electrochemical performance. Herein, we report the successful preparation of reduced graphene oxide coated Co3V2O8 micro-pencils (rGO@CVO MPs) through a facile approach combining hydrothermal synthesis with thermal reduction. When tested as anodes for LIBs, rGO@CVO MPs exhibit superior electrochemical performance compared to that of pure Co3V2O8 micro-pencils (pCVO MPs). The anodes of rGO@CVO MPs show a high reversible capacity of 760 mA h g−1 over 200 cycles at 200 mA g−1, and 500 mA h g−1 can remain after 500 cycles at 1000 mA g−1, with an increase in 200 mA h g−1 in contrast to the pCVO MPs. It is consequently demonstrated that the composite material (rGO@CVO MPs) is a promising anode material for LIBs. [ABSTRACT FROM AUTHOR]

The reactions of octacyanometallates [MoV(CN)8]3− and lanthanide ions in the solution of DMF (DMF = N,N-dimethylformamide) have yielded nine bimetallic coordination polymers: [LnIII(DMF)6MoV(CN)8]∞ [Ln = Pr(1), Nd(2), Sm(3), Eu(4), Gd(5), Ho(6), Er(7), Tm(8), Yb(9)]. All the coordination polymers consist of one-dimensional chains, in which [LnIII(DMF)6]3+ and [MoV(CN)8]3− ions link each other in an alternating fashion through the cyano-bridged coordination bonds. The variable-temperature magnetic susceptibility studies reveal the ferromagnetic interactions between LnIII and MoV ions in compounds 3 and 4, while antiferromagnetic interactions are found in compounds 1, 2, and 5–9. [ABSTRACT FROM AUTHOR]

Over the past decade, lanthanide compounds have become of increasing interest in the field of Single Molecule Magnets (SMMs) due to the large inherent anisotropy of the metal ions. Heavy lanthanide metal systems, in particular those containing the dysprosium(iii) ion, have been extensively employed to direct the formation of a series of SMMs. Although remarkable progress is being made regarding the synthesis and characterization of lanthanide-based SMMs, the understanding and control of the relaxation dynamics of strongly anisotropic systems represents a formidable challenge, since the dynamic behaviour of lanthanide-based SMMs is significantly more complex than that of transition metal systems. This perspective paper describes illustrative examples of pure dysprosium(iii)-based SMMs, published during the past three years, showing new and fascinating phenomena in terms of magnetic relaxation, aiming at shedding light on the features relevant to modulating relaxation dynamics of polynuclear lanthanide SMMs. [ABSTRACT FROM AUTHOR]

Monolayer of PDDA/graphene/PDDA/H2PtCl6is fabricated on conductive glass using electrostatic layer-by-layer self-assembly technique, which is then converted to graphene/Pt monolayer for use as counter electrode in dye-sensitized solar cell (DSSC). As compared to the sputtered Pt counter electrode, the self-assembled monolayer reduces the Pt amount by about 1000-fold but exhibits comparable photovoltaic performance. This finding provides a new route to fabrication of cheap and efficient counter electrodes for flow-line production of DSSCs. [ABSTRACT FROM AUTHOR]

Two dinuclear triple-stranded helicates [Ln2L3]3+(Ln = Dy and Tb) obtained viaself-assembly from the ligand HL (2,6-diformyl-4-methylphenol di(benzoylhydrazone)) and lanthanide perchlorate have been synthesized and characterized. The crystal structural analysis demonstrates that three ligand strands wrap around a pseudo-threefold axis defined by the two metal ions, leading to a ‘meso’-relation between the right- (Δ) and left-hand (Λ) configurations of [Ln2L3]3+in the crystal. Each LnIIIion is coordinated by nine donor atoms in a distorted tricapped trigonal-prismatic arrangement. Alternating current (ac) susceptibility measurements of [Dy2L3]3+reveal a frequency-dependent out-of-phase signal under a 700 Oe dc field, indicating the onset of the slow relaxation of magnetization with a roughly estimated activation energy of ∼5 K and τ0of 10−7s. [ABSTRACT FROM AUTHOR]

The reaction of Dy(NO3)3·6H2O with the ligand 2-((1-hydroxybutan-2-ylimino)methyl)phenol (H2L, Scheme 1) generates the nonanuclear compound [Dy9L8(μ3-OH)8(μ4-OH)2(CH3OH)8](OH)(CH3OH)3(Dy9), whose single-crystal X-ray structure reveals the presence of two square pyramidal pentanuclear units assembled viathe apical metal center. The square pyramidal core of a previously reported [Dy5(μ4-OH)(μ3-OH)4(μ-η2-Ph2acac)4(η2-Ph2acac)6] (Dy5; Ph2acac = dibenzoylmethanide), is structurally related to those herein described; however, the magnetic properties of Dy9and Dy5are drastically different. Indeed, Dy5shows slow relaxation of magnetization while no out-of-phase ac signal is noticed for Dy9. The underlying mechanism is not clear due to the complexity of such systems; however, the different anisotropy of the respective structures, which is dictated by the combination of the metal topology, the ligands involved and the structural parameters of the molecule, is mostly responsible for the distinctive relaxation dynamics observed. [ABSTRACT FROM AUTHOR]

Reactions of Ln(iii) acetate (Ln = Pr and Nd) and a polydentate Schiff-base in a mixture of methanol and acetonitrile resulted in the unprecedented assembly of novel Ln10aggregates containing two Ln5pentagons templated by μ5-CO32−, introduced viaspontaneous fixation of atmospheric carbon dioxide. Magnetic analysis using an expression including the ligand field effects and molecular field approximation indicates weak antiferromagnetic coupling between the metal ions. This synthetic approach may represent a promising new route toward the design of new lanthanide clusters and novel multifunctional materials. [ABSTRACT FROM AUTHOR]

Two new cyanide-bridged heterobimetallic coordination polymers constructed by using the [Au(CN)2]−building block, {Cd(bipy)[Au(CN)2]2}n(1) and {{Cd(phen)[Au(CN)2]2(H2O)}·iPrOH}n(2) (bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline), have been synthesized and characterized. Complex 1with chiral P3112 space group exhibits a novel three-fold interpenetrating quartz-like 3-D network, which is completely unsupported by aurophilic interactions, while complex 2with the replacement of bipy by phen shows C2/cspace group and features the 1-D zigzag chain structure and an extended supramolecular 2-D array in which aurophilic interactions may play an important role in sustaining the supramolecular solid-state architectures. 1and 2feature various networks most likely due to the different steric hindrances of the bipy and phen ligands. In addition, the solid state photoluminescence spectrum of complex 2exhibits a strong green emission band (λmax= 524 nm) at room temperature. [ABSTRACT FROM AUTHOR]

Nickel diselenide (NiSe2) has been synthesized and applied as a counter electrode (CE) of dye-sensitized solar cells (DSSCs) for the first time, which displays remarkable catalytic activity in the reduction of I3−. The DSSC with a NiSe2 CE produces a higher power conversion efficiency (8.69%) than that (8.04%) of the cell with a Pt CE under the same conditions. A new method for comparing the catalytic activity has also been proposed. [ABSTRACT FROM AUTHOR]

Utilization of the strong electron-withdrawing ligand, hfac, leads to a novel dinuclear dysprosium single-molecule magnet featuring a pyrazine bridge with a large anisotropic barrier. [ABSTRACT FROM AUTHOR]

Utilization of the strong electron-withdrawing ligand, hfac, leads to a novel dinuclear dysprosium single-molecule magnet featuring a pyrazine bridge with a large anisotropic barrier. [ABSTRACT FROM AUTHOR]

This work primarily exhibits a systematic study of the large-scale hydrothermal synthesis of β-Mn 2 V 2 O 7 interconnected nanospheres without templates. An optimal combination of hydrothermal/annealing/atmosphere parameters is identified for the pure phase, which exhibits an excellent cycling performance of 760 mA h g -1 at 0.5 A g -1 over 120 cycles and a rate capability of 470 mA h g -1 at 2 A g -1 as an anode for a lithium ion battery. Guidelines have been provided for the first time for the synthesis of β-Mn 2 V 2 O 7 , which opens broad opportunities for this earth-abundant chemical in electrochemical devices.

It is of great importance to search for efficient and stable metal-free catalysts toward electrochemical N2-to-NH3 conversion. In this communication, a chemically oxidized carbon nanotube material (O-CNT) is verified as an active electrocatalyst for the N2 reduction reaction under ambient conditions. In 0.1 M LiClO4, O-CNT achieves a large NH3 yield of 32.33 μg h-1 mgcat.-1 and a high faradaic efficiency of 12.50% at -0.4 V vs. the reversible hydrogen electrode. It also demonstrates superior stability. Density functional theory calculations suggest that C-O groups play a key role in the electrochemical N2 fixation.

Electrocatalytic N2 reduction as an alternative approach to the energy-intensive and large CO2-producing Haber-Bosch process for NH3 synthesis under mild conditions has attracted extensive attention. Current research efforts on N2 reduction have mainly focused on metal-based catalysts, but metal-free alternatives can avoid the issue of metal ion release. In this work, oxygen-doped hollow carbon microtubes (O-KFCNTs) derived from natural kapok fibers are reported as a metal-free NRR electrocatalyst for N2-to-NH3 conversion with excellent selectivity. In 0.1 M HCl, the O-KFCNTs achieve a high faradaic efficiency of 9.1% at -0.80 V vs. a reversible hydrogen electrode (RHE) and a NH3 yield rate of 25.12 μg h-1 mgcat.-1 at -0.85 V vs. RHE under ambient conditions. Notably, this catalyst also demonstrates high stability.

Nickel diselenide (NiSe(2)) has been synthesized and applied as a counter electrode (CE) of dye-sensitized solar cells (DSSCs) for the first time, which displays remarkable catalytic activity in the reduction of I(3)(-). The DSSC with a NiSe(2) CE produces a higher power conversion efficiency (8.69%) than that (8.04%) of the cell with a Pt CE under the same conditions. A new method for comparing the catalytic activity has also been proposed.

In this work, reduced graphene oxide (RGO) sheets are successfully introduced into the conductive polypyrrole (PPy) matrix as conductive channels and co-catalyst, through simple incorporation of graphene oxide (GO) into PPy and subsequent in situ reduction from GO/PPy to RGO/PPy composite film. The RGO/PPy film is fabricated as a counter electrode for dye-sensitized solar cells, and it exhibits excellent catalytic performance for reduction of triiodide. For this reason, the incorporated RGO sheets significantly improve short-circuit photocurrent density from 14.27 to 15.81 mA cm(-2) and power conversion efficiency from 7.11% to 8.14%, which is comparable with that for the cell based on a Pt cathode.

A new cyano-bridged Tb(III)-Cr(III) heterometallic complex [Tb(H(2)O)(2)(DMF)(4){Cr(CN)(6)}]·H(2)O (DMF = dimethylformamide) (1), assembled from paramagnetic hexacyanochromium(III) [Cr(CN)(6)](3-) building block and highly anisotropic terbium(III) ion has been prepared and structurally and magnetically characterized. Complex 1 shows one-dimensional (1D) zig-zag chain-like structural motif which is further extended into three-dimensional network through hydrogen-bonding interactions. The long-range magnetic ordering observed in complex 1, which is possibly due to interchain magnetic dipolar interactions, illuminates that this complex is a molecule-based magnet with critical temperature of about 5 K. This higher critical temperature among those of Ln(III)-Cr(III) heterometallic complexes exhibiting long-range magnetic ordering is probably due to the introduction of highly anisotropic terbium(III) ion.

An enneanuclear nickel(II) complex with a rectangular face-centered trigonal prism structure bridged by μ(2)-pyrazolate, μ(6)-CO(3)(2-) and μ(3)-OH(-) groups was synthesized. It displays cluster glass-like magnetic behavior assigned to the single molecule magnet properties of {Ni(9)} clusters and weak intercluster interaction., (This journal is © The Royal Society of Chemistry 2012)

The reaction of Dy(NO(3))(3)·6H(2)O with the ligand 2-((1-hydroxybutan-2-ylimino)methyl)phenol (H(2)L, ) generates the nonanuclear compound [Dy(9)L(8)(μ(3)-OH)(8)(μ(4)-OH)(2)(CH(3)OH)(8)](OH)(CH(3)OH)(3) (Dy(9)), whose single-crystal X-ray structure reveals the presence of two square pyramidal pentanuclear units assembled via the apical metal center. The square pyramidal core of a previously reported [Dy(5)(μ(4)-OH)(μ(3)-OH)(4)(μ-η(2)-Ph(2)acac)(4)(η(2)-Ph(2)acac)(6)] (Dy(5); Ph(2)acac = dibenzoylmethanide), is structurally related to those herein described; however, the magnetic properties of Dy(9) and Dy(5) are drastically different. Indeed, Dy(5) shows slow relaxation of magnetization while no out-of-phase ac signal is noticed for Dy(9). The underlying mechanism is not clear due to the complexity of such systems; however, the different anisotropy of the respective structures, which is dictated by the combination of the metal topology, the ligands involved and the structural parameters of the molecule, is mostly responsible for the distinctive relaxation dynamics observed., (This journal is © The Royal Society of Chemistry 2011)

The asymmetric Cole-Cole plots observed in a remarkable linear Dy(III) compound suggests the occurrence of multiple relaxations most likely associated with distinct anisotropic centres, thus opening new avenues for investigating the relaxation dynamics of lanthanide aggregates.

The reaction of Pr(NO(3))(3).6H(2)O with the ligand 2-hydroxy-N-(2'-hydroxyethyl)-3-methoxybenzamide (H(3)L) in MeOH-MeCN generates the nonanuclear compound [Pr(9)(H(2)L)(8)(OH)(10)(NO(3))(8)](NO(3))(H(2)O)(2)(CH(3)CN) (), whose single-crystal X-ray structure reveals the presence of metallacalix[4]arene cavities that host guest molecules. The crystal packing of the antiferromagnetic Pr(9) cluster shows an intricate network of hydrogen bonds producing a one-dimensional supramolecular chain.

A unique purely lanthanide-based single-molecule magnet (SMM) with an oxalate bridge has been designed through a rational synthetic approach. This strategy opens up new opportunities to design SMMs through the premeditated choice of a blocking ligand and suitable oxalate bridge.

Reactions of Ln(III) acetate (Ln = Pr and Nd) and a polydentate Schiff-base in a mixture of methanol and acetonitrile resulted in the unprecedented assembly of novel Ln(10) aggregates containing two Ln(5) pentagons templated by mu(5)-CO(3)(2-), introduced via spontaneous fixation of atmospheric carbon dioxide. Magnetic analysis using an expression including the ligand field effects and molecular field approximation indicates weak antiferromagnetic coupling between the metal ions. This synthetic approach may represent a promising new route toward the design of new lanthanide clusters and novel multifunctional materials.