Syntheses,structures, and luminescent properties of cadmium (II) complexes: 3D supramolecular [Cd(phen)(NO3)(NO2)(H2O)]n and Cd(phen)2(NO3)(NO2) constructed by π–π stacking interactions

Two novel complexes [Cd(phen)(NO₃)(NO₂)(H₂O)]_n (1) and Cd(phen)₂(NO₃)(NO₂) (2) (phen = 1,10-phenanthroline) have been synthesized by the reductive reaction of metal source Cd(NO₃)₂·4H₂O with phen and benzidine in the mixed solution of DMF, ethanol and water. Crystal structures of complexes 1 and 2 were determined by single-crystal X-ray diffraction. Complex 1 is a one-dimensional (1D) zig-zag infinite chain in which (phen)Cd^(II) units were bridged by two O atoms of NO₂⁻. The three-dimensional (3D) supramolecular structure of 1 is constructed through hydrogen-bond and aromatic π–π stacking interactions between adjacent metal–organic polymeric coordination chains. Complex 2 is a mononuclear structure, and self-assembled through π–π stacking interactions to form a three-dimensional (3D) supramolecular structure. The complex 1 exhibits luminescent property in the near-UV at room temperature in solutions of DMSO and DMF with the emission energy following the order DMF < DMSO, which might be ascribed to the presence of a highly polarized ground state. Complexes 1 and 2 have blue-purple luminescence at room temperature in the solid state. The blue-purple luminescence of the complexes is due to π* → π transition of phen.     

The photovoltaic performance of new ruthenium complexes in DSSCs based on nanorod ZnO electrode

Three new heteroleptic ruthenium complexes, [Ru(L1)(dcbpy)(NCS)₂] Ru^II(4,7-diphenyl-1,10-phenanthroline-disulfonic acid disodium salt)(4,4′-dicarboxy-2,2′-bipyridyl)-di(thiocyanate) [K28], [Ru^II(L1)₂(NCS)₂] Ru^IIbis(4,7-diphenyl-1,10-phenanthroline-disulfonic acid disodium salt)-di(thiocyanate) [K313], and [Ru(L2)(dcbpy)(NCS)₂] Ru^II(1,10-phenanthroline-5,6-dione)(4,4′-dicarboxy-2,2′-bipyridyl)-di(thiocyanate) [K27], have been synthesized as sensitizers for dye-sensitized solar cells (DSSCs) using ZnO nanorod electrode. The photovoltaic performances of the solar cells based on these sensitizer dyes are studied under AM 1.5 irradiation (100 mW/cm²). Their photophysical and electrochemical properties are also investigated. ZnO nanorod based dye sensitized solar cell sensitized with K28 ruthenium complex bearing bulky sulfoxy groups gives an overall conversion efficiency of 2.51, a short-circuit current of 7.19 mA/cm², and an open circuit voltage of 550 mV. K28 is firstly designed and synthesized in the literature to increase molar extinction coefficients and enhanced spectral response in the visible light by expanding the π-conjugation, and of course to reduce back electron transfer due to the bulky sulfoxy groups. The vertical excitation energies, corresponding excitation wavelengths and oscillator strengths, predominant orbitals involved in ten singlet–singlet transitions and their characters obtained from the single point TD-DFT calculations have been obtained for K28.     

High energy ion irradiation effect on light-emitting poly(3-methylthiophene) (P3MT) nanowires

Light-emitting poly(3-methylthiophene) (P3MT) nanowires with a diameter of ∼200 nm were fabricated using an electrochemical polymerization method based on an anodic alumina oxide (Al₂O₃) nanoporous template. The relatively high energy (3 MeV) Cl²⁺ ions were irradiated onto the P3MT nanowires with dosages from 1 × 10¹³ to 1 × 10¹⁵ ions/cm². To study the effect of high energy ion irradiation on P3MT nanowires, we measured UV/vis absorbance, Raman spectra, and laser confocal microscope photoluminescence (PL) on the nanometer scale. The relative atomic concentrations of carbon elements in the pristine and the 3 MeV Cl²⁺ ion-irradiated P3MT nanowires were investigated through XPS experiments. As the dosage of the 3 MeV Cl²⁺ ion irradiation increased, we observed that the P3MT nanowires changed to a partially carbonized form, and that the PL efficiency of the systems decreased.     

Formation of ‘ferric green rust’ and/or ferrihydrite by fast oxidation of iron(II-III) hydroxychloride green rust

Fast oxidation processes of iron(II-III) hydroxychloride green rust GR(Cl⁻), Fe^II₃Fe^III(OH)₈Cl · 2H₂O, were simulated by two different methods. The first one consisted in using a strong oxidiser, namely H₂O₂. The main end product, analysed by X-ray diffraction and Mössbauer spectroscopy, is an iron(III) compound, designated as “ferric GR(Cl⁻)”, characterised by a layered structure identical to that of normal GR(Cl⁻). The second method consisted in decreasing the initial concentrations of reactants, thus increasing the proportion of dissolved O₂. Suspensions of GR(Cl⁻), obtained by mixing 4 × 10⁻³ M NaOH with FeCl₂ solutions for various R^′=[Cl⁻]/[OH⁻] values, oxidised rapidly into ferrihydrite-like compounds.     

Influence of metal ions on the formation of artificial zinc rusts

The artificial rust particles were prepared from ZnCl₂ solutions dissolving Al(III), Fe(III), Fe(II), Ni(II), Co(II) and Mg(II) at different atomic ratios from 0 to 0.3 in metal/Zn. With increasing metal/Zn the crystal phases of the products turned following as ZnO → a mixture of ZnO and Zn₅(OH)₈Cl₂ · H₂O (ZHC) → ZHC. Al(III) most facilitated the formation of ZHC but Mg(II) and Fe(III) produced no ZHC. The morphology of the formed particles varied following as agglomerate → fine → rod → sheet → irregular with the increase of metal/Zn. The sheet and irregularly shaped particles were identified as ZHC and the other particles as ZnO.     

Structure and properties of selected (Cr–Al–N,TiC–C,Cr–B–N) nanostructured tribological coatings

The paper will present the state-of-art in the process, structure and properties of nanostructured multifunctional tribological coatings used in different industrial applications that require high hardness, toughness, wear resistance and thermal stability. The optimization of these coating systems by means of tailoring the structure (graded, superlattice and nanocomposite systems), composition optimization, and energetic ion bombardment from substrate bias voltage control to provide improved mechanical and tribological properties will be assessed for a range of coating systems, including nanocrystalline graded Cr_1−xAl_xN coatings, superlattice CrN/AlN coatings and nanocomposite Cr–B–N and TiC/a-C coatings. The results showed that the superlattice CrN/AlN coating exhibited a super hardness of 45 GPa when the bilayer period Λ was about 3.0 nm. Improved toughness and wear resistance have been achieved in the CrN/AlN multilayer and graded CrAlN coatings as compared to the homogeneous CrAlN coating. For the TiC/a-C coatings, increasing the substrate bias increased the hardness of TiC/a-C coatings up to 34 GPa (at −150 V) but also led to a decrease in the coating toughness and wear resistance. The TiC/a-C coating deposited at a −50 V bias voltage exhibited an optimized high hardness of 28 GPa, a low coefficient of friction of 0.19 and a wear rate of 2.37 × 10⁻⁷ mm³ N⁻¹ m⁻¹. The Cr–B–N coating system consists of nanocrystalline CrB₂ embedded in an amorphous BN phase when the N content is low. With an increase in the N content, a decrease in the CrB₂ phase and an increase in the amorphous BN phase were identified. The resulting structure changes led to both decreases in the hardness and wear resistance of Cr–B–N coatings.     

Capacitive properties of RuO2 and Ru–Co mixed oxide deposited on single-walled carbon nanotubes for high-performance supercapacitors

Composite electrodes for use in redox supercapacitors were prepared by electrochemical deposition of RuO₂ or the co-deposition of Ru–Co mixed oxides on the surface of single-walled carbon nanotubes. Electrodes coated with the Ru–Co mixed oxide [Ru (13.13 wt%) and Co (2.89 wt%)] or RuO₂, exhibited a similar specific capacitance (∼620 F g⁻¹) at low potential scan rates (10 mV s⁻¹). However, at higher scan rates (500 mV s⁻¹) the mixed metal oxide electrode showed superior performance (570 F g⁻¹) when compared to the RuO₂ electrode (475 F g⁻¹). This increase in capacitance at high scan rates is attributed to the role of the Co in providing enhanced electronic conduction.     

Influence of Ti(IV) on the structure and properties of zinc hydroxychloride

Layered material of zinc hydroxychloride (Zn₅(OH)₈Cl₂ · H₂O: ZHC), which is one of the basic zinc salts (BZS), prepared from ZnO nano-particles aged with aqueous ZnCl₂ solutions containing TiCl₄ was examined by various means. The Ti/(Ti + Zn) atomic ratio (X_Ti) was ranged from 0 to 0.10. XRD results indicated that the diffraction intensity of ZHC was decreased with increasing X_Ti. The ZHC formed at X_Ti = 0 is hexagonal plate particles with ca. 4 μm in size and ca. 0.2 μm in thickness. The particle size was reduced by doping Ti(IV) and the irregular particles were generated at X_Ti ? 0.03. The Ti content was increased with increasing X_Ti and Ti(IV) was more easily incorporated in the products than Zn(II). Diffuse reflection UV-vis results suggested that Ti(IV) in the products at X_Ti ? 0.01 is tetrahedral coordination and that at X_Ti ? 0.03 is a mixture of tetrahedral and octahedral ones. These facts prove that Ti(IV) inhibits the formation and crystal growth of ZHC. The specific surface area of Ti-doped ZHC estimated from N₂ adsorption isotherms was increased with increasing X_Ti owing to the decrease of particle size. Contrary to the N₂ adsorption, H₂O monolayer adsorption capacity per unit surface area was reduced as X_Ti increased. This seems that the layered structure of ZHC, which is accessible to H₂O molecules but not to N₂ molecules, is disintegrated by incorporation of Ti(IV). Similarly, adsorption of CO₂ on ZHC was inhibited by doping Ti(IV).     

On the formation of β-FeOOH (akaganéite) in chloride-containing environments

Fe(III) oxyhydroxides were synthesised in chlorinated environments via chemical or electrochemical processes in order to determine the conditions favouring the formation of akaganéite. Corrosion products were characterised using X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy. The first method produced Fe(III) oxyhydroxides from the aerial oxidation of iron(II) precipitates which were obtained by mixing FeCl₂ · 4H₂O and NaOH solutions. Depending on the initial amounts of Fe²⁺, Cl⁻ and OH⁻, goethite, lepidocrocite or akaganéite were then obtained. When a large excess of dissolved FeCl₂ was present, akaganéite was formed independently of the oxygen flow. In the second method, steel electrodes were left in baths containing chloride with [Cl⁻] = 2 mol L⁻¹, using either FeCl₂ · 4H₂O or NaCl. Akaganéite was obtained exclusively in the FeCl₂ solutions, confirming that to obtain the formation of this compound, both iron(II) and chloride concentrations must be important.     

Effect of calcium ions on pitting corrosion and inhibition performance in CO2 corrosion of N80 steel

The electrochemical impedance spectroscopy (EIS) and polarization resistance technique were used to investigate the susceptibility of N80 steel to pitting corrosion under stagnant condition and the corrosion behavior under flowing condition with/without precorrosion in 3% NaCl solution, in 3% NaCl + 1.5% CaCl₂ solution and in 4.6% NaCl solution (equivalent Cl⁻ concentration to 3% NaCl + 1.5% CaCl₂ solution) saturated by CO₂ at 57 °C. The results showed that under stagnant condition the initiation period of pitting corrosion decreased with increasing Cl⁻ concentration, but at the same Cl⁻ concentration, Ca²⁺ could prolong the initiation period. Under flowing condition the corrosion rate without stagnant precorrosion was bigger than that with precorrosion, and the corrosion rate with precorrosion in 3% NaCl solution was bigger than that in 3% NaCl + 1.5% CaCl₂ solution. Inhibition of quaternary alkynoxymethyl amine (IMC-80-Q) under stagnant condition showed that the optimum inhibitor concentration significantly increased with the increase of Cl⁻ concentration from 3% NaCl solution to 4.6% NaCl solution, and for the solutions with the same Cl⁻ concentration, adding Ca²⁺ did not change the optimum inhibitor concentration.     

Mechanical properties, deformation behaviors and interface adhesion of (AlCrTaTiZr)Nx multi-component coatings

In this study, (AlCrTaTiZr)N_x multi-component coatings with quinary metallic elements were developed as protective hard coatings for tribological application. The mechanical properties, creep behaviors, deformation mechanisms and interface adhesion of the (AlCrTaTiZr)N_x coatings with different N contents were characterized. With increasing the N₂-to-total (N₂ + Ar) flow ratio, R_N, during sputtering deposition, the (AlCrTaTiZr)N_x coatings transformed from an amorphous metallic phase to a nanocomposite and finally a crystalline nitride structure. The hardness of the coatings accordingly increased from 13 GPa to a high value of about 30 GPa, but the creep strain rate also increased from 1.3 × 10^− 4 to 7.3 × 10^− 4 1/s. The plastic deformation of the amorphous metallic coating deposited with R_N = 0% proceeded through the formation and extension of shear bands, whereas dislocation activities dominated the deformation behavior of the crystalline nitride coatings deposited with R_N = 10% and 30%. With increasing R_N, the interface adhesion energy between the coatings and the substrates was also enhanced from 6.1 to 22.9 J/m².     

Prevention of passive film breakdown and corrosion of iron in 0.1 M KClO4 with and without Cl by covering with an ultrathin two-dimensional polymer coating and healing treatment in 0.1 M NaNO3

A two-dimensional polymer coating, the self-assembled monolayer of 16-hydroxy hexadecanoate ion HO(CH₂)₁₅ modified with 1,2-bis(triethoxysilyl)ethane (C₂H₅O)₃Si(CH₂)₂Si(OC₂H₅)₃ and octadecyltriethoxysilane C₁₈H₃₇Si(OC₂H₅)₃ was prepared on the passivated iron electrode and further, the passive film was healed by additional treatment in 0.1 M NaNO₃. This electrode was immersed in oxygenated 0.1 M KClO₄ solutions with and without 1 × 10⁻⁴ to 1 × 10⁻² M of Cl⁻. Protection of passive film against breakdown by covering the electrode with the polymer coating was examined by monitoring the open-circuit potential during immersion in the solutions for many hours to determine the time for passive film breakdown, t_bd. Repeated polarization measurements were carried out during immersion in these solutions for obtaining the protective efficiency, P. The t_bd value of the passivated, polymer-coated and healed electrode in 0.1 M KClO₄ solutions with and without Cl⁻ increased with a decrease in the concentration of Cl⁻. No breakdown occurred on the electrode during immersion in 0.1 M KClO₄ solutions with and without 1 × 10⁻⁴ of Cl⁻ for 360 h. The P values were extremely high, more than 99.9% before t_bd, indicating complete protection of iron from corrosion. The effect of healing treatment in 0.1 M NaNO₃ on passive film breakdown was investigated by electron-probe microanalysis.     

EQCN study of anodic dissolution and surface oxide film formation at Au in the presence of Cl or Br ions: A model process for corrosion studies

The anodic dissolution of an Au electrode and associated thin-layer oxide film formation in aq. H₂SO₄ in the presence of Cl⁻ or Br⁻ ions at various concentrations provides a model process for metal corrosion. In the present work such processes were investigated using cyclic voltammetry and chronoamperometry, with complementary nanogravimetry measurements using the EQCN. The results clearly indicate that in 0.5 M H₂SO₄ electrolyte, containing 1 mM Br⁻ or Cl⁻, Au dissolves over the potential range 1.0 - 1.45 V(RHE) through a 3e oxidation process involving Au complex-ion formation that can be followed in situ by means of UV spectroscopy. The linear relationship between mass changes and reciprocal square-root of sweep-rate and between anodic currents in cyclic voltammetry at ca. 1.20 V for Br⁻ (1.39 V for Cl⁻) and square-root of sweep-rate/or electrode rotation rate indicated quantitatively that the dissolution process is diffusion-controlled. It was interesting to find that electrode rotation in the presence of Cl⁻ ions has little effect on the anodic formation of surface oxide, while, on the contrary, with Br⁻ ions present, currents for oxide film reduction are not observed at rotation rates > ca. 400 rpm.     

Stable hole-transporting molecular glasses based on complicated 9,9-diarylfluorenes (CDAFs)

A series of complicated 9,9-diarylfluorenes (CDAFs) with highly thermal and morphological stability, end-capped oligothiophenes (T)_n(PF)_m (n = 1–3, m = 2) and triphenylamines TPA(PF)_m (m = 1–3), were synthesized via BF₃·Et₂O-mediated Friedel–Crafts reaction. TPA(PF)₂ with bulky 9-phenylfluorene moieties (PFMs) as a morphological stabilizer possesses excellently amorphous solid state with a glass transition temperature (T_g) up to 140 °C and no T_g was observed for TPA(PF)₃ with high decomposition temperature up to 499 °C. Preliminary characterizations of typical double-layer devices with the configuration of ITO/TPA(PF)₃/AlQ₃/Mg:Ag show luminance efficiency of ca. 2.25 cd/A at 100 cd/m² with a maximum brightness of ca. 8300 cd/m².     

High color rendering white organic light-emitting diodes fabricated using a broad-bandwidth red phosphorescent emitter for lighting applications

High color rendering white organic light-emitting devices (WOLEDs) were developed using a broad-bandwidth red phosphorescent iridium complex, bis[2-(1-naphthyl)benzothiazolato-N,C²′]iridium(III) acetylacetonate [Ir(absn)₂(acac)]. The red phosphorescent emitter Ir(absn)₂(acac) was used to fabricate blue–red and blue–green–red WOLEDs by combining blue-emitting bis[2-(4,6-difluorophenyl)pyridinato-N,C²′]iridium(III) picolinate (FIrpic) and green-emitting tris-fac-(2-cyclohexenylpyridine) iridium (III) [Ir(chpy)₃] in multiple-emissive layers. Mixed host emissive layers were employed using a hole-transport-type host 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA) and an electron-transport-type host 2,6-bis[3-(carbazol-9-yl)phenyl]pyridine (DCzPPy) for efficient charge carrier injection. Di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane (TAPC) and 1,3-bis(3,5-dipyrid-3-yl-phenyl)benzene (BmPyPB) were used as the hole and electron transporting layers, respectively. The effects of the emissive layer thickness and the doping ratios of different color dopants on WOLED performances were investigated. The WOLED based on ITO/TAPC/TCTA:FIrpic (10%):Ir(absn)₂(acac) (4%)/TCTA:Ir(chpy)₃ (9%, 6 nm)/DCzPPy:FIrpic (13%):Ir(absn)₂(acac) (4%)/BmPyPB/LiF/Al exhibited an external quantum efficiency of 10.7%, a power efficiency of 23.0 lm/W, a very high color rendering index (CRI) of 88.1, and a correlated color temperature (CCT) of 2629 K at 1000 cd/m².     

P-type transparent conducting SnO2:Zn film derived from thermal diffusion of Zn/SnO2/Zn multilayer thin films

Highly transparent, p-type conducting SnO₂:Zn thin films are prepared from the thermal diffusion of a sandwich structure of Zn/SnO₂/Zn multilayer thin films deposited on quartz glass substrate by direct current (DC) and radio frequency (RF) magnetron sputtering using Zn and SnO₂ targets. The deposited films were annealed at various temperatures for thermal diffusion. The effect of annealing temperature and time on the structural, electrical and optical performances of SnO₂:Zn films was studied. XRD results show that all p-type conducting films possessed polycrystalline SnO₂ with tetragonal rutile structure. Hall effect results indicate that the treatment at 400 °C for 6 h was the optimum annealing parameters for p-type SnO₂:Zn films which have relatively high hole concentration and low resistivity of 2.389 × 10¹⁷ cm^− 3 and 7.436 Ω cm, respectively. The average transmission of the p-type SnO₂:Zn films was above 80% in the visible light range.     

Microstructure and mechanical properties of quaternary Cr–Si–O–N films by a hybrid coating system

Quaternary Cr–Si–O–N films were deposited by a hybrid coating system using a Cr cathodic arc target and a Si sputtering target in an Ar/N₂/O₂ gaseous mixture. The influence of oxygen flux rate on the microstructure and properties of the Cr–Si–O–N films were investigated. The results indicated that the oxygen-free Cr–Si–N film exhibited nanocolumnar microstructure containing CrN nano columns and amorphous Si₃N₄ phase. The Cr–Si–O–N films exhibit equiaxed CrN nanocrystallites likely surrounded by amorphous SiO₂ and Si₃N₄ phases. Further increasing the oxygen content gives films containing Cr₂O₃ crystallites. The hardness first increases from 30 GPa for the Cr–Si–N film to a maximum value of approximately 50 GPa for the oxygen content of 16 at.% and then decreases for larger oxygen content. All the Cr–Si–O–N films exhibit low friction coefficient (0.22–0.26) and low residual stress (− 0.03–0.08 GPa). The influence of the oxygen content on the microstructure and mechanical properties of the Cr–Si–O–N films is discussed.     

Synthesis of two benzo[1,2-b:3,4-b′]dithiophene-based conjugated polymers with different side chains and their applications in photovoltaic devices

Two D–A conjugated polymers (named PBDTC₆DBT and PBDTC₁₀DBT) with benzo[1,2-b:3,4-b′]dithiophene (BDT) as donor and 4,7-dithiophen-2,1,3-benzothiadiazole (DBT) as acceptor, were designed and synthesized. PBDTC₆DBT and PBDTC₁₀DBT have hexyl and decyl as side chains in the DBT units, respectively. The polymers were characterized by spectroscopic (NMR and UV–vis) methods, GPC, DSC and cyclic voltammetry. In order to study the photovoltaic properties of the two conjugated polymers, photovoltaic devices with the configuration of ITO/poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS)/polymer:[6,6]-phenyl C₆₁-butyric acid methyl ester (PC₆₁BM)/LiF/Al, were fabricated, in which PBDTC₆DBT or PBDTC₁₀DBT acted as electron donor in active layers. According to the experimental data, when the blend ratio of PBDTC₆DBT and PC₆₁BM reached 1:2, the best photovoltaic properties among the PBDTC₆DBT-based devices were obtained, and the open-circuit voltage, the short-circuit current density and the power conversion efficiency were measured to be 0.63 V, 6.18 mA/cm² and 1.86%, respectively. As to PBDTC₁₀DBT-based devices, the maximum of power conversion efficiency reached 0.99% with the blend ratio of PBDTC₁₀DBT and PC₆₁BM being 1:2. PBDTC₁₀DBT and PBDTC₆DBT were both promising donor candidates in the application of polymer solar cells.     

Electrodeposition of Co–Sb thermoelectric film from ethylene glycol–CoCl2–SbCl3 solution

The electrodeposition of cobalt–antimony thermoelectric semiconductor films was investigated in a non-aqueous solution of ethylene glycol (EG)–CoCl₂–SbCl₃ at 393 K. By controlling the bath composition and cathodic current density, Co–Sb alloys containing 0–94 mol% of Co were obtained at 50–300 Am^− 2. The resistance polarization caused by the formation of semiconductor film was observed in the polarization curve measured in the EG–CoCl₂–SbCl₃ (90.0–9.3–0.7 mol%) bath. In this bath, the Co–Sb (23.6–76.4 mol%) alloy was obtained by maintaining the constant potential electrolysis at 0.1 V. This alloy included CoSb₃ and exhibited a p-type thermoelectric conversion by the given temperature difference.     

Environmental factors affecting the corrosion behavior of reinforcing steel II. Role of some anions in the initiation and inhibition of pitting corrosion of steel in Ca(OH)2 solutions

Potential-time curves are constructed for the steel electrode in naturally aerated Ca(OH)₂ solutions simulating the corrosion behavior in concrete. Cl⁻ and SO₄²⁻ ions cause the destruction of passivity and initiation of pitting corrosion. The rate of oxide film growth by Ca(OH)₂ and oxide film destruction by Cl⁻ and SO₄²⁻ ions follows a direct logarithmic law as evident from the linear relationships between the open-circuit potential and the logarithm of immersion time. Chromate, phosphate, nitrite, tungstate and molybdate ions inhibit the pitting corrosion of steel. The rate of oxide film healing and thickening increases with their concentrations. In presence of constant inhibitor concentration, the efficiency of pitting inhibition increases in the order: (weak) CrO₄²⁻ < HPO₄²⁻ < NO₂⁻ < WO₄²⁻ < MoO₄²⁻ (strong).