Spectroscopic Signature of the Carbon-Carbon Coupling Reaction between Carbon Monoxide and Nickel Carbide.

Spectroscopic characterization of ketenylidene complexes is of essential importance for understanding the structure-reactivity relationships of the catalytic sites. Here, we report a size-specific photoelectron velocity map imaging spectroscopic study of the reactions of carbon monoxide with nickel carbide. Quantum chemical calculations have been conducted to search for the energetically favorable isomers and to recognize the experimental spectra. The target products with the chemical formula of NiC(CO)n- (n = 3-5) are characterized to have an intriguing ketenylidene CCO unit. The evolution from NiC(CO)3- to NiC(CO)4- involves the breaking and formation of the Ni-C bond and the coordination conversion between the terminal and bridging carbonyls. Experimental and theoretical analyses reveal an efficient C-C bond formation process within the reactions of carbon monoxide and laser-vaporized nickel carbide. This work highlights the pivotal roles played by metal carbides in the C-C bond formation and also proposes new ideas for the design and chemical control of a broad class of complexes with unique physical and chemical properties.

Piezoelectricity and Thermophysical Properties of Ba0.90Ca0.10Ti0.96Zr0.04O3 Ceramics Modified with Amphoteric Nd3+ and Y3+ Dopants.

Lead-free barium calcium titanate zirconate (BCTZ) ceramics doped with a single rare-earth element generally exhibit excellent piezoelectric properties. However, their electrical properties deteriorate at an excessive dopant content, limiting their application. In this study, amphoteric neodymium (Nd3+) and yttrium (Y3+)-codoped BCTZ-NYx ceramics were synthesized via a solid-state reaction at 1240 °C. The influences of the Y3+ content (x) on the structural features, electrical properties, mechanical properties, and thermophysical properties were investigated. At a small x (<0.18 mol%), Y3+ could enhance the fracture strength and electrical properties by eliminating oxygen vacancies, defect dipoles, and/or structural defects. However, the outstanding performance deteriorated with excessive x. Additionally, the mechanism of the defect chemistry at different x was deduced. At an yttrium content of 0.18 mol%, the ceramic exhibited high piezoelectricity and ferroelectricity with low domain-switching activation energy (Ea = 0.401 eV), indicating that it could replace commercial lead-based piezoelectric ceramics.

Synthesis and Characterization of Single-Phase α-Cordierite Glass-Ceramics for LTCC Substrates from Tuff.

Single-phase α-cordierite glass-ceramics for a low-temperature co-fired ceramic (LTCC) substrate were fabricated from tuff as the main raw material, using the non-stoichiometric formula of α-cordierite with excess MgO without adding any sintering additives. The sintering/crystallization behavior and the various performances of dielectric properties, thermal expansion, and flexural strength of the glass-ceramics were detected. The results indicated that only single-phase α-cordierite crystal was precipitated from the basic glass sintered at the range 875-950 °C, and µ-cordierite crystal was not observed during the whole sintering-crystallization process. The properties of glass-ceramics were first improved and then deteriorated with the increase in tuff content and sintering temperature. Fortunately, the glass-ceramics sintered at 900 °C with 45 wt.% tuff content possessed excellent properties: high densify (2.62 g∙cm-3), applicable flexural strength (136 MPa), low dielectric loss (0.010, at 10 MHz), low dielectric constant (5.12, at 10 MHz, close to α-cordierite), and suitable coefficients of thermal expansion (CTE, 3.89 × 10-6 K-1).

Supramolecular Precursor Strategy to Construct g-C3N4/Silica Hybrid Nanosheets for Photocatalytic Degradation of Dye and Antibiotic Pollutants.

To construct a highly active g-C3N4 (CN)/silica hybrid nanosystem, the supramolecular precursor strategy of introducing melamine-cyanuric acid (MCA) by synergistically using micromolecular melamine (m) and urea (u) for CN nanostructure construction on the silica nanosheets (SiNSs) surface was researched. The results showed that the introduction of MCA supramolecular aggregates promoted the generation of ordered CN nanostructures attached to SiNSs, and the morphology of the CN nanostructure could be regulated through the m/u mass ratio. When the ratio is equal to 1/30, a typical g-C3N4/silica hybrid nanosheet (mu-CN/SiNSs-3) was successfully prepared, which showed the ultra-high photocatalytic activity for Rhodamine B dye degradation within 25 min with an apparent rate constant of 0.186 min-1, owing to the large surface area of highly dispersed and ordered CN nanosheets, a strong interaction between CN and SiNSs, high photogenerated carriers separation efficiency, and the more negative conduction band potential offering more active species of 1O2 and •O2-. Unexpectedly, the mu-CN/SiNSs-2 composite (m/u = 1/10) exhibited the highest activity for tetracycline antibiotic degradation, mainly due to the morphological advantage of a certain number of nanotubes generated on the CN/SiNSs hybrid nanosheets. It indicates that the supramolecular precursor strategy by synergistically using melamine and urea is highly efficient for the nanostructure construction of the CN/SiNSs hybrid system, enabling an appropriate nanostructure for the photodegradation of various pollutants.

Self-induced matrix with Li-ion storage activity in ultrathin CuMnO2 nanosheets electrode.

Conversion anode materials such as Mn3O4 draw much attention due to their considerable theoretical capacity for lithium-ion batteries (LIBs). However, poor conductivity, slow solid-state Li-ion diffusion, and huge volume expansion of the active materials during charge/discharge lead to unsatisfied electrochemical performance. Despite several strategies like nanocrystallization, fabricating hierarchical nanostructures, and introducing a matrix are valid to address these crucial issues, the achieved electrochemical performance still needs to be further enhanced. What is worse, the matrix with less or no Li-ion storage activity may lower the achieved capacity of the electrodes. Herein, ultra-thin CuMnO2 nanosheets with the thickness of 5-8 nm were evaluated for LIBs. The ultra-thin sheet-like nanostructure offers sufficient contact areas with electrolyte and shortens the Li-ion diffusion distance. Moreover, the in-situ generated Mn and Cu along with their oxides could play the role of matrix and conductive agent in turn at different stages, relieving the stress brought by volume expansion. Therefore, the as-prepared ultra-thin CuMnO2 nanosheets electrode displays a remarkable reversible capacity, long cycling stability, and outstanding rate capability (a reversible capacity of 1160.5 mAh g-1 at 0.1A g-1 was retained after 100 cycles with a capacity retention of 95.1 %, and 717.8 mAh g-1 at 2.0 A g-1 after 400 cycles).

Heterostructure engineering of ultrathin SnS2/Ti3C2Tx nanosheets for high-performance potassium-ion batteries.

Layered metal sulfides are considered as promising candidates for potassium ion batteries (KIBs) owing to the unique interlayer passages for ion diffusion. However, the insufficient electronic conductivity, inevitable volume expansion, and sulfur loss hinder the promotion of K-ion storage performance. Herein, few-layered Ti3C2Tx nanosheets were selected as the multi-functional substrate for cooperating few-layered SnS2 nanosheets, constructing SnS2/Ti3C2Tx hetero-structural nanosheets (HNs) with the thickness as thin as about 5 nm. In this configuration, the formed Ti-S bonds provide robust interaction between SnS2 and Ti3C2Tx nanosheets, which hinders the agglomeration of SnS2 and the restack of Ti3C2Tx, endowing the hybrid material with robust nanostructure. Thus, the shortcomings of the SnS2 anode are muchly relieved. In this way, the as-prepared SnS2/Ti3C2Tx HNs electrode delivers reversible capacities of 462.1 mAh g-1 at 0.1 A g-1 and 166.1 mAh g-1 at 2.0 A g-1, respectively, and a capacity of 85.5 mAh g-1 is remained even after 460 cycles at 2.0 A g-1. These results are superior to those of the counterpart electrode, confirming aggressive promotion of K-ion storage performance of SnS2 anode brought by the cooperation of Ti3C2Tx, and presenting a reliable strategy to improve the electrochemical performance of sulfide anodes.

Stimulating the Reversibility of Sb2 S3 Anode for High-Performance Potassium-Ion Batteries.

Conversion-alloy sulfide materials for potassium-ion batteries (KIBs) have attracted considerable attention because of their high capacities and suitable working potentials. However, the sluggish kinetics and sulfur loss result in their rapid capacity degeneration as well as inferior rate capability. Herein, a strategy that uses the confinement and catalyzed effect of Nb2 O5 layers to restrict the sulfur species and facilitate them to form sulfides reversibly is proposed. Taking Sb2 S3 anode as an example, Sb2 S3 and Nb2 O5 are dispersed in the core and shell layers of carbon nanofibers (C NFs), respectively, constructing core@shell structure Sb2 S3 -C@Nb2 O5 -C NFs. Benefiting from the bi-functional Nb2 O5 layers, the electrochemical reversibility of Sb2 S3 is stimulated. As a result, the Sb2 S3 -C@Nb2 O5 -C NFs electrode delivers the rapidest K-ion diffusion coefficient, longest cycling stability, and most excellent rate capability among the controlled electrodes (347.5 mAh g-1 is kept at 0.1 A g-1 after 100 cycles, and a negligible capacity degradation (0.03% per cycle) at 2.0 A g-1 for 2200 cycles is delivered). The enhanced K-ion storage properties are also found in SnS2 -C@Nb2 O5 -C NFs electrode. Encouraged by the stimulated reversibility of Sb2 S3 and SnS2 anodes, other sulfides with high electrochemical performance also could be developed for KIBs.

Role of microporous Janus silica nanosheets in the assembly of ultra-small Ag nanoparticles with high catalytic activity.

As an emerging nano-silica material, two-dimensional (2D) silica nanosheets (SiNSs) have been derived from natural layered kaolinite and applied as a substrate for the highly efficient and dispersed assembly of functional materials, such as noble metal nanoparticles (NPs). In this work, the nature of SiNSs and its particular role in the assembly of ultra-small AgNPs via the reduction-growth method using a Sn(ii) reductant were further researched. By adjusting the Sn(ii) content x (1.2-6.0 wt%), it was found that the surface areas of the Sn(ii)-activated SiNSs (xSn-SiNSs) had almost no change, and their reducibility did not fully increase with the increased x values, due to the saturated adsorption of the Sn(ii) reductant by the surface hydroxyls of the SiNSs, which subsequently caused the decrease of the adsorbed Ag(i) precursor by the hydroxyls on the xSn-SiNSs (x≥ 4.8 wt%). Accordingly, the sizes and loading amounts of the resultant AgNPs mainly showed a similar trend of increase before decrease. Furthermore, the regulated AgNPs with diverse mean sizes ranging from 1.71 to 2.16 nm were all ultra-small (more than half were nanoclusters < 2 nm) and highly dispersed, owing to the high electrostatic attraction of the negatively charged hydroxyls and the anchoring effect of the micropores on the hydroxylated surface of the Janus SiNSs. Therefore, the Ag/xSn-SiNSs nanocomposites displayed better catalytic properties for 4-nitrophenol reduction than most Ag-based supported catalysts, and the optimal Ag/2.4Sn-SiNSs catalyst exhibited quick reaction within 80 s and turnover frequency (TOF) of 3.34 min-1. It reveals the key role of negatively charged surface hydroxyls and micropores of Janus SiNSs in the highly efficient and dispersed assembly of functional materials.

Photoelectron Velocity Map Imaging Spectroscopic and Theoretical Study of Heteronuclear MNi(CO)7- (M = V, Nb, Ta).

A series of heteronuclear group 5 metal-nickel carbonyls MNi(CO)7- (M = V, Nb, Ta) have been generated via a laser ablation ion source and studied by photoelectron velocity-map imaging spectroscopy. Quantum chemical calculations have been performed to probe the electronic and geometric structures and help to assign the spectra. The adiabatic detachment energies (ADEs) and vertical detachment energies (VDEs) are deduced from spectra to be 3.40/3.58, 3.34/3.55, 3.30/3.50 eV, which are consistent with quantum chemical computational results. The MNi(CO)7- (M = V, Nb, Ta) consists of three bridging carbonyls, one carbonyl terminally bonded to the Ni atom and three carbonyls terminally bonded to the M (M = V, Nb, Ta) atom. These geometries are different from homobinuclear Cr2(CO)7+, Ni2(CO)7+, Pd2(CO)7+, and Fe2(CO)7- and heterobinuclear CuFe(CO)7-, CoZn(CO)7+, and CO is largely activated by a bridging coordination mode. The experimental and theoretical results would provide important information to understand the chemisorbed CO molecules on alloy surfaces or interfaces, which is of great significance to elucidate CO molecule activation processes.

CuO Nanoplates for High-Performance Potassium-Ion Batteries.

Potassium-ion batteries (KIBs) are promising alternatives to lithium-ion batteries because of the abundance and low cost of K. However, an important challenge faced by KIBs is the search for high-capacity materials that can hold large-diameter K ions. Herein, copper oxide (CuO) nanoplates are synthesized as high-performance anode materials for KIBs. CuO nanoplates with a thickness of ≈20 nm afford a large electrode-electrolyte contact interface and short K+ ion diffusion distance. As a consequence, a reversible capacity of 342.5 mAh g-1 is delivered by the as-prepared CuO nanoplate electrode at 0.2 A g-1 . Even after 100 cycles at a high current density of 1.0 A g-1 , the capacity of the electrode remains over 206 mAh g-1 , which is among the best values for KIB anodes reported in the literature. Moreover, a conversion reaction occurs at the CuO anode. Cu nanoparticles form during the first potassiation process and reoxidize to Cu2 O during the depotassiation process. Thereafter, the conversion reaction proceeds between the as-formed Cu2 O and Cu, yielding a reversible theoretical capacity of 374 mAh g-1 . Considering their low cost, easy preparation, and environmental benignity, CuO nanoplates are promising KIB anode materials.

Engineering the Core-Shell-Structured NCNTs-Ni2Si@Porous Si Composite with Robust Ni-Si Interfacial Bonding for High-Performance Li-Ion Batteries.

A new strategy has been innovatively proposed for wrapping the Ni-incorporated and N-doped carbon nanotube arrays (Ni-NCNTs) on porous Si with robust Ni-Si interfacial bonding to form the core-shell-structured NCNTs-Ni2Si@Si. The hierarchical porous silicon core was first fabricated via a novel self-templating synthesis route based on two crucial strategies: in situ thermal evaporation of crystal water from the perlite for producing porous SiO2 and subsequent magnesiothermic reduction of porous SiO2 into porous Si. Ni-NCNTs were subsequently constructed based on the Ni-catalyzed tip-growth mechanism and were further engineered to fully wrap the porous Si microparticles by forming the Ni2Si alloy at the heterojunction interface. When the prepared NCNTs-Ni2Si@Si was evaluated as the anode material for Li-ion batteries, the hierarchical porous system in the Si core and the rich void spaces in carbon nanotube arrays contributed to the remarkable accommodation of volume expansion of Si as well as the significant increase of Li+ diffusion and Si utilization. Moreover, the Ni2Si alloy, which chemically linked the Ni-NCNTs and porous Si, not only provided good electronic contact between the Si core and carbon shell but also effectively prevented the CNTs' detachment from the Si core during cycling. The multifunctional structural design rendered the whole electrode highly stable and active in Li storage, and the electrochemically active NCNTs-Ni2Si@Si electrode delivered a high reversible capacity of 1547 mAh g-1 and excellent cycling stability (85% capacity retention after 600 discharge-charge cycles) at a current density of 358 mA g-1 (0.1 C) as well as good rate performance (778 mAh g-1 at 2 C), showing great potential as an efficient and stable anode for high energy density Li-ion batteries.

Strategic Design of Vacancy-Enriched Fe1- xS Nanoparticles Anchored on Fe3C-Encapsulated and N-Doped Carbon Nanotube Hybrids for High-Efficiency Triiodide Reduction in Dye-Sensitized Solar Cells.

A new class of hybrids with the unique electrocatalytic nanoarchitecture of Fe1- xS anchored on Fe3C-encapsulated and N-doped carbon nanotubes (Fe1- xS/Fe3C-NCNTs) is innovatively synthesized through a facile one-step carbonization-sulfurization strategy. The efficient synthetic protocols on phase structure evolution and dynamic decomposition behavior enable the production of the Fe1- xS/Fe3C-NCNT hybrid with advanced structural and electronic properties, in which the Fe vacancy-contained Fe1- xS showed the 3d metallic state electrons and an electroactive Fe in +2/+3 valence, and the electronic structure of the CNT was effectively modulated by the incorporated Fe3C and N, with the work function decreased from 4.85 to 4.63 eV. The meticulous structural, electronic, and compositional control unveils the unusual synergetic catalytic properties for the Fe1- xS/Fe3C-NCNT hybrid when developed as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs), in which the Fe3C- and N-incorporated CNTs with reduced work function and increased charge density provide a highway for electron transport and facilitate the electron migration from Fe3C-NCNTs to ultrahigh active Fe1- xS with the electron-donating effect, and the Fe vacancy-enriched Fe1- xS nanoparticles exhibit ultrahigh I3- adsorption and charge-transfer ability. As a consequence, the DSSC based on the Fe1- xS/Fe3C-NCNT CE delivers a high power conversion efficiency of 8.67% and good long-term stability with a remnant efficiency of 8.00% after 168 h of illumination, superior to those of traditional Pt. Furthermore, the possible catalytic mechanism toward I3- reduction is creatively proposed based on the structure-activity correlation. In this work, the structure engineering, electronic modulation, and composition control opens up new possibilities in constructing the novel electrocatalytic nanoarchitecture for highly efficient CEs in DSSCs.

Nitrogen self-doped carbon aerogels derived from trifunctional benzoxazine monomers as ultralight supercapacitor electrodes.

Ultralight benzoxazine-derived porous nitrogen self-doped carbon aerogels with good yield can be prepared by direct polymerization of trifunctional benzoxazine monomers under acid catalysis using concentrated hydrochloric acid. This allows for a significantly widened density range (0.8-4.5 mg cm-3) and avoids any sacrificial etching. When serving as electrode materials for supercapacitors, the resulting hierarchical porous carbon aerogels show ultrahigh specific capacitance, excellent rate performance and good cycling stability (retention of 97.3% even after 10 000 continuous charge-discharge cycles). Besides energy storage devices, the interconnected nanoporous carbon aerogels can also find applications in oil/water separation, heavy metal removal, catalyst supports, and so forth.

Three-dimensional flower-like MoS2-CoSe2 heterostructure for high performance superccapacitors.

A novel three-dimensional (3D) flower-like MoS2-CoSe2 heterostructure has been designed and synthesized by a facile two-step hydrothermal process as the electrode materials for supercapacitors. The MoS2-CoSe2 heterostructure is demonstrated to deliver a high specific capacitance (2577 F g-1 at 1 A g-1) and remarkable rate capability (896 F g-1 at 20 A g-1). Besides, the MoS2-CoSe2 electrode also exhibits excellent cycling stability of 91.03% capacitance retention after 5000 cycles even at a relatively high current density of 20 A g-1. A two-electrode configuration symmetric supercapacitor based MoS2-CoSe2 heterostructure delivers a maximum energy density of 60.5 W h kg-1 at a power density of 800 W kg-1 and the energy density remains at 35.6 W h kg-1 at a power density of 8000 W kg-1. Excellent cycling stability is also achieved with 83.62% retention after 2000 charge-discharge cycles, revealing its potential and viability for practical applications. The outstanding electrochemical performances of the fabricated electrode stem from the unique structure characteristic of the flower-like MoS2-CoSe2 heterostructure. The high-quality heterointerface facilitates electron conduction while the porosity not only allows fast ion transport but provides abundant active sites for Faradic reaction and the buffer for volume variety in repeat charge-discharge process. The design strategy offers a new idea for fabricating high-performance supercapacitor electrode materials.

Phosphonate-Stabilized Titanium-Oxo Clusters with Ferrocene Photosensitizer: Structures, Photophysical and Photoelectrochemical Properties, and DFT/TDDFT Calculations.

The metal-to-core charge transfer (MCCT) transition in sensitized titanium-oxo clusters is an important process for photoinduced electron injection in photovoltaic conversion. This process resembles most closely the Type II photoinjection in dye-sensitized solar cells. Herein we report the synthesis and photophysical and photoelectrochemical (PEC) properties of the phosphonate-stabilized titanium-oxo clusters containing the ferrocenecarboxylate ligands. These ferrocene-containing clusters exhibit intense visible absorption extended up to 600 nm along with low optical band gaps of ∼2.2 eV. The low-energy transitions of these clusters were systematically investigated by UV-vis spectroscopy and DFT/TDDFT calculations. The combined experimental and computational studies suggest that the ferrocenecarboxylate-substituted titanium-oxo clusters form a donor-acceptor (D-A) system. The low-energy transition of these clusters primarily involves the MCCT from the iron center to TiO cluster core. The TiO core structure and phosphonate ligands both have great influence on the PEC properties of the clusters. This work provides valuable examples for the sensitized titanium-oxo clusters in which electron injection takes place via MCCT transition.

A 4-dimethylaminobenzoate-functionalized Ti6-oxo cluster with a narrow band gap and enhanced photoelectrochemical activity: a combined experimental and computational study.

Organic donor-π-bridge-acceptor (D-π-A) dyes with arylamines as an electron donor have been widely used as photosensitizers for dye-sensitized solar cells (DSSCs). However, titanium-oxo clusters (TOCs) functionalized with this kind of D-π-A structured dye-molecule have rarely been explored. In the present study, the 4-dimethylaminobenzoate-functionalized titanium-oxo cluster [Ti6(µ3-O)6(OiPr)6(DMABA)6]·2C6H5CH3 (DMABA = 4-dimethylaminobenzoate) was synthesized and structurally characterized by single-crystal X-ray diffraction. For comparison, two other Ti6-oxo clusters, namely [Ti6(µ3-O)6(OiPr)6(AD)6] (AD = 1-adamantanecarboxylate) and [Ti6(µ3-O)2(µ2-O)(µ2-OiPr)4(OiPr)10(DMM)2] (DMM = dimethylmalonate), were also studied. The DMABA-functionalized cluster exhibits a remarkably reduced band gap of ∼2.5 eV and much enhanced photocurrent response in comparison with the other two clusters. The electronic structures and electronic transitions of the clusters were studied by DFT and TDDFT calculations. The computational results suggest that the low-energy transitions of the DMABA-functionalized cluster have a substantial charge-transfer character arising from the DMABA → {Ti6} cluster core ligand-to-core charge transfer (LCCT), along with the DMABA-based intra-ligand charge transfer (ILCT). These low-energy charge transfer transitions provide efficient electron injection pathways for photon-to-electron conversion.

Strong Blue Emissive Supramolecular Self-Assembly System Based on Naphthalimide Derivatives and Its Ability of Detection and Removal of 2,4,6-Trinitrophenol.

Two simple and novel gelators (G-P with pyridine and G-B with benzene) with different C-4 substitution groups on naphthalimide derivatives have been designed and characterized. Two gelators could form organogels in some solvents or mixed solvents. The self-assembly processes of G-P in a mixed solvent of acetonitrile/H2O (1/1, v/v) and G-B in acetonitrile were studied by means of electron microscopy and spectroscopy. The organogel of G-P in the mixed solvent of acetonitrile/H2O (1/1, v/v) formed an intertwined fiber network, and its emission spectrum had an obvious blue shift compared with that of solution. By contrast, the organogel of G-B in acetonitrile formed a straight fiber, and its emission had an obvious red shift compared with that of solution. G-P and G-B were employed in detecting nitroaromatic compounds because of their electron-rich property. G-P is more sensitive and selective toward 2,4,6-trinitrophenol (TNP) compared with G-B. The sensing mechanisms were investigated by 1H NMR spectroscopic experiments and theoretical calculations. From these experimental results, it is proposed that electron transfer occurs from the electron-rich G-P molecule to the electron-deficient TNP because of the possibility of complex formation between G-P and TNP. The G-P molecule could detect TNP in water, organic solvent media, as well as using test strips. It is worth mentioning that the organogel G-P can not only detect TNP but also remove TNP from the solution into the organogel system.

A ferrocenecarboxylate-functionalized titanium-oxo-cluster: the ferrocene wheel as a sensitizer for photocurrent response.

Sensitized titanium-oxo clusters (TOCs) have attracted growing interest. However, reports on TOCs incorporated with a metal complex as photosensitizers are still very rare. In the present work, the organometallic complex ferrocene was used as a sensitizer for a titanium-oxo cluster. A ferrocenecarboxylate-substituted titanium-oxo cluster [Ti6(µ3-O)6(OiPr)6(O2CFc)6] (Fc = ferrocenyl) was synthesized and structurally characterized, in which the ferrocene wheel performs as a sensitizer for photocurrent response. For comparison, naphthalene-sensitized titanium-oxo clusters [Ti6(µ3-O)6(OiPr)6(NA)6] (NA = 1-naphthoate) and [Ti6(µ3-O)6(OiPr)6(NAA)6] (NAA = 1-naphthylacetate) with the same {Ti6} core structure were also synthesized. The structures, optical behaviors, electronic states and photoelectrochemical properties of these sensitized {Ti6} clusters were investigated. It is demonstrated that the introduction of ferrocene groups into the titanium-oxo cluster significantly reduces the band gap and enhances the photocurrent response in comparison with the naphthalene-sensitized clusters. The substantially reduced band gap of the ferrocene-sensitized cluster was attributed to the introduction of Fe(ii) d-d transitions and the possible contribution from the Fc → {Ti6} charge transfer. For the naphthalene-sensitized clusters, the better electronic coupling between the dye and the {Ti6} core in the 1-naphthoate (NA) substituted cluster results in higher photoelectrochemical activity.

General Strategy for Controlled Synthesis of NixPy/Carbon and Its Evaluation as a Counter Electrode Material in Dye-Sensitized Solar Cells.

Hydrothermal treatment of nickel acetate and phosphoric acid aqueous solution followed with a carbothermal reduction assisted phosphorization process using sucrose as the carbon source for the controlled synthesis of NixPy/C was successfully realized for the first time. The critical synthesis factors, including reduction temperature, phosphorus/nickel ratio, pH, and sucrose amount were systematically investigated. Remarkably, the carbon serves as a reducer and plays a determinative role in the transformation of Ni2P2O7 into Ni2P/C. The synthesis strategy is divided into four distinguishable stages: (1) hydrothermal preparation of Ni3(PO4)2·8H2O precursor for stabilizing P sources; (2) dimerization of Ni3(PO4)2·8H2O into more thermal stable Ni2P2O7 amorphous phase along with the generation of NiO; (3) carbothermal reduction and phosphidation of NiO into NixPy (0 ≤ y/x ≤ 0.5); and (4) further phosphidation of mixed-phase NixPy and carbothermal reduction of Ni2P2O7 into single-phase Ni2P. The resultant Ni2P, the highly active phase in electrocatalysis, was applied as counter electrode in a dye-sensitized solar cell (DSSC). The DSSC based on Ni2P with 10.4 wt.% carbon delivers a power conversion efficiency of 9.57%, superior to that of state-of-the-art Pt-based cell (8.12%). The abundant Niδ+ and Pδ- active sites and the metal-like conductivity account for its outstanding catalytic performance.

Enhanced sensing of dopamine in the present of ascorbic acid based on graphene/poly(p-aminobenzoic acid) composite film.

Graphene/p-aminobenzoic acid composite film modified glassy carbon electrode (Gr/p-ABA/GCE) was first employed for the sensitive determination of dopamine (DA). The electrochemical behavior of DA at the modified electrode was investigated by cyclic voltametry (CV), differential pulse voltametry (DPV) and amperometric curve. The oxidation peak currents of DA increased dramatically at Gr/p-ABA/GCE. The modified electrode was used to electrochemically detect dopamine (DA) in the presence of ascorbic acid (AA). The Gr/p-ABA composite film showed excellent electrocatalytic activity for the oxidation of DA in phosphate buffer solution (pH 6.5). The peak separation between DA and AA was large up to 220 mV. Using DPV technique, the calibration curve for DA determination was obtained in the range of 0.05-10 µM. The detection limit for DA was 20 nM. AA did not interfere with the determination of DA because of the very distinct attractive interaction between DA cations and the negatively Gr/p-ABA composite film. The proposed method exhibited good stability and reproducibility.