Efficient polymer solar cells based on dialkoxynaphthalene and benzo[c][1,2,5]thiadiazole: A new approach for simple donor-acceptor pair

We reported the synthesis of novel polymeric semiconductor materials based on [poly(4-(5-(1,5-bis(alkoxy)naphthalen-2-yl)thiophen-2-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]-thiadiazole)] (PANTBT) and the fabrication of solar cells with a power conversion efficiency of 4.2% using the synthesized polymers blended with [6,6]-phenyl C₇₁ butyric acid methyl ester (PC₇₀BM) in bulk heterojunction geometry. By varying the side chains, three polymers were synthesized [poly(4-(5-(1,5-bis(2-ethylhexyloxy)naphthalen-2-yl)thiophen-2-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PENTBT), [poly(4-(5-(1,5-bis(decyloxy)naphthalen-2-yl)thiophen-2-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PDNTBT), and [poly(4-(5-(1,5-bis(tetradecyloxy)naphthalen-2-yl)thiophen-2-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PTDNTBT), maintaining a low highest occupied molecular orbital (HOMO) energy level and relatively low band gap, which lead to a high open circuit voltage and short circuit current of the resulting devices. Due to the superior miscibility of PANTBT derivatives with PC₇₀BM, favorable phase separation with a domain size of 10-20 nm was achieved regardless of the crystalline nature of the pristine polymers. PDNTBT with alkyl side chain C10 and PTDNTBT with alkyl side chain C14 showed higher photovoltaic performances. In addition, the effects of the crystalline nature of polymers on the thermal stability of the resulting solar cell devices were discussed in terms of the influence of side chains.     

Low band gap poly-thienopyrazines for solar cells—Introducing the 11-thia-9,13-diaza-cyclopenta[b]triphenylenes

The chemistry of the thienopyrazines has been explored with the aim of producing new low band gap polymers. 5,7-Di-(thiophen-2-yl)-thieno[3,4-b]pyrazines substituted in the pyrazine ring with alkyl groups, aryl groups and fused aromatic rings have been prepared and characterized. The electronic spectra show a great variation in the longest wavelength absorption band as a consequence of this substitution. A special case is the 11-thia-9,13-diaza-cyclopenta[b]triphenylene prepared by condensation of 3′,4′-diamino-[2,2′,5′,2″]terthiophene with phenanthrene-9,10-quinone. Alkyl substitution of the most promising monomers were carried out using the Kumada coupling and these were copolymerized with either 2,5-bis(trimethylstannyl)thiophene or 3-(3,7,11-trimethyl-dodecyl)-2,5-bis-trimethylstannyl-thiophene to form six new low band gap polymers: RISO-GREEN 1–3 and RISO-BROWN 1–3. The band gaps of these polymers were estimated from the UV–visible absorption spectra and found to be ca. 1.3 eV. Preliminary results from photovoltaic device fabrication with mixtures of the six polymers with either [60]PCBM or [70]PCBM gave modest efficiencies of max 0.2% with open circuit voltages V_oc of 0.3 V and short circuit currents J_sc (1000 Wm⁻² AM1.5) in the range of 2 mA cm⁻².     

Mercury(II)-complex with 5-methyl-1,3,4-thiadiazole-2-thiol: kinetic studies of hydrogen storage

Mixed ligand mercury(II) complexes of 2-meracpto-5-methyl-1,3,4-thiazdiazole (HmtzS) and phosphines or diamines having the general formulae [Hg(mtsZ)₂(diphos)] {diphos = 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino)butane (dppe), 1,1′-bis(diphenylphosphino)ferrocene (dppf)}, [Hg(mtsZ)₂(PPh₃)₂] and [Hg(mtsZ)₂(diamine)] {diamine = bipyridyl (Bipy) or 1,10-phenthroline (Phen), were successfully synthesized by simple mixing method. The complexes were characterized by elemental analysis, molar conductivity, IR and NMR (¹H, ¹³C and ³¹P) spectroscopic methods. The mtzS^? ligand was coordinated through the sulfur atom of thiol group, whereas the diphosphine or diamine ligands bonded as bidentate chelating ligand to afford tetrahedral environment around the Hg(II) ions. Moreover, the complex [Hg(mtsZ)₂] was used in order to study its ability to store hydrogen. The results of hydrogen isotherm at different temperatures prove that [Hg(mtsZ)₂] was able to store 0.8 wt% at a pressure of 80 bar 77 K. Furthermore, the kinetic study of hydrogen storage was studied and the kinetic study was carried out using the Langmuir. Moreover, the adsorption kinetic results revealed that hydrogen storage in [Hg(mtsZ)₂] follow the pseudo-second-order model with coefficient regression equal to 0.99.     

Co(III) carboxamide complexes as electrocatalysts for water splitting

Water splitting is a promising approach for storing intermittent renewable energies, such as sunlight in the clean chemical bonds as a hydrogen fuel. Two water-soluble octahedral cobalt (III) complexes, [Co(bpb)(OAc)(H₂O)], 1, (bpb^2? = N,N′-bis[(2-pyridine carboxamide)-1,2-benzene] dianion) and [Co(cbpb)(OAc)(H₂O)], 2, (cbpb^2? = N,N′-bis[(2-pyridine carboxamide)-4-chloro-1,2-benzene] dianion) were synthesised and characterised by CHN elemental analysis, UV–Vis, FT-IR and single-crystal X-ray diffraction techniques. The two carboxamide ligands had been prepared in the ionic liquid TBAB as an environmentally benign reaction medium. The electrocatalytic water splitting activity of 1 and 2 showed that both complexes are highly active for the water splitting in aqueous solutions. Turn Over Frequency (TOF) values were, for 1 and 2 respectively, 527 and 490 mol of hydrogen in each mole of catalyst per hour at an overpotential of 738 mV (pH = 7.0). Such a performance can be ascribed to the flat ligands, the electroactivity of the metal centre and carboxamide ligands and the ability of losing the axial ligands around the metal-ion centre during the reduction process which provide different reduction pathways for an HER process.     

Enhanced hydrogen storage capacity of NiAl-layered double hydroxide modified with Tb3Fe5O12 nanostructures

Under ultrasonic irradiation, the porous Tb₃Fe₅O₁₂ (TFO) and Nickel Aluminum layer double hydroxide (NiAl-LDH) were synthesized by investigation the effect of sonication time. Synthesis of TFO was conducted in the presence of tetradentate Schiff-base ligand H₂salophen, [N,N′-bis(salicylidene)-1,2-phenylenediamine] as complexing agent to size controlling and further growth prevention of crystals. The resultant nanocomposites of TFO/NiAl-LDH used as novel active compounds for applying in hydrogen storage strategies. Comprehensively, the hydrogen capacitance after 15 cycles was displayed on the pure NiAl-LDH and TFO materials about 115 and 334 mAhg⁻¹ respectively. It demanded the maximum capacitance for Tb₃Fe₅O₁₂/NiAl-LDH nanocomposites was 451 mAhg⁻¹, which was higher than the initial NiAl-LDH structure. It was exposed from the spillover effect that; the endorsed electrochemical hydrogen storage (EHS) performance is ascribed to the reaction of the redox pair of Fe³⁺/Fe²⁺ at the active sites throughout the EHS procedure. This work delivers a novel plan and potential sorption electrode materials to progress the intrinsic action of layered compounds.     

Electrochemical characterization of blend polymer electrolytes based on poly(oligo[oxyethylene]oxyterephthaloyl) for rechargeable lithium metal polymer batteries

Solid polymer electrolytes composed of poly(ethylene oxide)(PEO), poly(oligo[oxyethylene]oxyterephthaloyl) and lithium perchlorate have been prepared and characterized. Addition of poly(oligo[oxyethylene]oxyterephthaloyl) to PEO/LiClO₄ reduced the degree of crystallinity and improved the ambient temperature ionic conductivity. The blend polymer electrolyte containing 40 wt.% of poly(oligo[oxyethylene]oxyterephthaloyl) showed an ionic conductivity of 2.0 × 10⁻⁵ S cm⁻¹ at room temperature and a sufficient electrochemical stability to allow application in the lithium batteries. By using the blend polymer electrolytes, the lithium metal polymer cells composed of lithium anode and LiCoO₂ cathode were assembled and their cycling performances were evaluated at 40 °C.     

Enhanced water splitting through different substituted cobalt-salophen electrocatalysts

Synthesis of stable catalysts for water splitting is important for the renewable and clean energy production. Here, water oxidation activities of cobalt (II) complexes CoL¹-CoL³ (1–3) with salophen type ligands (N,N′-bis(salicylidene)-4-chloro-1,2-phenylendiamine (H₂L¹), N,N′-bis(salicylidene)-4-bromo-1,2-phenylendiamine (H₂L²) and N,N′-bis(salicylidene)-4-nitro-1,2-phenylendiamine (H₂L³)) are studied by electrochemical techniques, FE-SEM images and XRD patterns. Linear sweep voltammetry studies indicate that 2 and 3 have superior activities and only require the overpotential of 316 and 247 mV vs. RHE at current density of 10 mA/cm² with Tafel slopes of 75 and 50 mVdec^?1 at pH = 11. Experiments show relationships between the stability of the complexes and their catalytic activity. It is revealed that substituents on ligands affect the catalytic behaviors. Experiments show that in the presence of 2 and 3, the complexed cobalt ions are likely candidates as molecular catalysts for water oxidation. It is speculated that the O–O bond formation occurs by oxidizing the active center of cobalt complexes.     

Calculation of band gap in long alkyl-substituted heterocyclic-thiophene-conjugated polymers with electron donor–acceptor fragment

Since the interaction between alternating donors and acceptors results in a diminished band gap, a low band gap (<1.8 ev) will be expected in polymers containing donor–acceptor (D–A) repeating units. In order to predict the band gaps for guiding the synthesis of novel materials with low band gaps, we apply quantum-chemical techniques to calculate the band gaps in several polythiophene (PT) copolymers with D–A repeating units: poly{5,7-bis(3-octyl thiophen-2-yl)thieno-[3,4-b]pyrazine}(OTP), poly{5,7-di(thiophen-2-yl)thieno[3,4-b]-pyrazine}(TP), poly{4-(4-hexyl-5-(3-hexylthiophen-2-yl)thiophen-2-yl)benzo-[c][1, 2, 5]thiadiazole(HH-OTB), and poly{4-(5-(thiophen-2-yl)thiophen-2-yl) benzo[c]-[1,2,5]thiadiazole(TB). The geometries of the oligomers were optimized using semi-empirical AM1. The band gap calculations on these oligomers were performed by density functional theory (DFT) (B3LYP/3–21G*) and DFT (B3LYP/6–31G*). Band gaps of the corresponding polymers were obtained by extrapolating oligomers gaps to infinite chain lengths. The results indicate that calculated band gaps are in good agreement with the experimental values, in particular for long alkyl-substituted copolymer (HH-OTB/OTP). In addition, long alkyl side chain can induce steric hindrance, which leads to destroyed chain coplanar and increased band gap (>1.8 ev) in thiophene copolymers with alternate D–A units.     

Improving the efficiency of organic solar cell with a novel ambipolar polymer to form ternary cascade structure

This study describes the utilization of a novel conjugated copolymer, namely, poly[2,3-bis(thiophen-2-yl)-acrylonitrile-9,9′-dioctyl-fluorene] (FLC8) for organic solar cell application for the first time. The highest occupied molecular orbital and the lowest unoccupied molecular orbital of FLC8 are −5.68 and −3.55 eV, respectively, which lie between the corresponding values of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methylester (PCBM). In addition, both electron and hole mobilities of FLC8 are in the range of 10⁻⁴ (cm²/V s), making it an excellent ambipolar polymer. Such unique properties make FLC8 a good candidate to form a ternary cascade bulk-heterojunction organic solar cell when blending with P3HT and PCBM. The power conversion efficiency (PCE) of the ternary cascade solar cell can be increased by up to 30% as compared with the reference cell without FLC8. We suspect that this enhancement of PCE is caused by the additional charge separation offered by the cascade structure and the fast charge transfer due to the ambipolarity of FLC8.     

Tuning the microstructure of organosilica membranes with improved gas permselectivity via the co-polymerization of 1,2-bis(triethoxysilyl)ethane and 1,2-bis(triethoxysilyl)methane

1,2-bis(triethoxysilyl)ethane (BTESE)-derived membranes have proven thermal and hydrothermal stability and molecular sieving properties. However, BTESE-derived membranes still have low gas permselectivity due to their loose structure. Herein, we propose a novel strategy of co-polymerization using precursors of both BTESE and 1,2-bis(triethoxysilyl)methane (BTESM) to improve the gas permselectivity of BTESE-derived membranes. BTESM is introduced into BTESE network and the microstructure can be adjusted by different molar ratios of BTESE to BTESM. We find that, as the content of BTESM increase, H₂ permeations of BTESE-BTESM membranes remain nearly constant, while the permeations of larger gases (CO₂ and N₂ etc.) exhibit a greatly decreased. The membrane with a molar ratio of BTESE:BTESM = 3:7 exhibits the highest H₂/CO₂ (11.3) and H₂/N₂ (26.8) permselectivity while having a relatively high H₂ permeance (1.52 × 10^?6 mol m² s^?1?Pa^?1). Our findings may provide novel insights into preparation of co-polymerization organosilica membranes with excellent H₂/CO₂ and H₂/N₂ separation performance.     

Novel benzothiophene based catalyst with enhanced activity for glucose electrooxidation

Thiophene based heterocyclic compounds plays important roles in organic chemistry due to their unexpected properties. Herein, novel benzothiophene derivatives (6A-F) are synthesized via Sonogashira coupling, iodocyclization reaction, Suzuki-Miyaura coupling and condensation reactions. After characterization of design molecules, their glucose electrooxidation activities are investigated. Electrochemical measurements are performed by cyclic voltammetry, chrono amperometry, and electrochemical impedance spectroscopy in 1 M KOH +0.5 M C₆H₁₂O₆ solution. This results show that the highest performance organic-based catalysts is obtained as 0.729 mA/cm² (3.345 mA/mg) for the 2-(4-(2-pentylbenzo [b]thiophen-3-yl)benzylidene)malononitrile (6B). Furthermore, 6B catalyst is shown long term stability, the best current density value (1.151 mA cm⁻²), and the best transfer resistance load between organic-based catalysts. As a result, it is clear that these benzothiophene derivatives are promising organic based catalyst, an alternative to the expensive Pd and Pt based metal catalyst, for direct glucose fuel cell anode.     

A new lithium salt with dihydroxybenzene and lithium tetrafluoroborate for lithium battery electrolytes

A new unsymmetrical lithium salt containing F⁻, C₆H₄O₂²⁻ [dianion of 1,2-benzenediol], lithium difluoro(1,2-benzene-diolato(2-)-o,o′)borate (LDFBDB) is synthesized and characterized. Its thermal decomposition in nitrogen begins at 170 °C. The cyclic voltammetry study shows that the LDFBDB solution in propylene carbonate (PC) is stable up to 3.7 V versus Li⁺/Li. It is soluble in common organic solvents. The ionic dissociation properties of LDFBDB are examined by conductivity measurements in PC, PC+ ethyl methyl carbonate (EMC), PC + dimethyl ether (DME), PC + ethylene carbonate (EC) + EMC solutions. The conductivity values of the 0.564 mol dm⁻³ LDFBDB electrolyte in PC + DME solution is 3.90 mS cm⁻¹. All these properties of the new lithium salt including the thermal characteristics, electrochemical stabilities, solubilities, ionic dissociation properties are studied and compared with those of its derivatives, lithium difluoro(3-fluoro-1,2-benzene-diolato(2-)-o,o′)borate (FLDFBDB), lithium [3-fluoro-1,2-benzenediolato(2-)-o,o′ oxalato]borate (FLBDOB), and lithium bis(oxalate)borate (LBOB).     

Design of high-efficiency solid-state dye-sensitized solar cells using coupled dye mixtures

A solid-state dye-sensitized solar cell comprising dye mixtures of [Ru(2,2-bpy-4,4′-dicarboxylic acid)(NCS)₂] and [Ru(4,4′,4″-tricarboxy-2,2;6,2″-terpy)(NCS)₃] on TiO₂ thin film was fabricated. The different optical properties of dyes results in increased photocurrent and incident photon to photocurrent efficiency (IPCE). The multiple dye system showed the short circuit current (I_sc) of 10.2 mA/cm² and a cell efficiency (η) of 2.8 while broadening the spectral sensitivity of the cell. When a single dye is used, I_sc of 6 and 5 mA/cm² and cell efficiency of 1.7 and 1.2 were observed for [Ru(4,4-bis(carboxy)-bpy)₂(NCS)₂] (dye 1) and [Ru(2,2′,2″-(COOH)₃-terpy)(NCS)₃] (dye 2), respectively. Additionally, the resulting IPCE for the solar cell consisting of dye mixture was 50% at wide wavelength range from 530 to 650 nm while for the dye 1, 32% IPCE was observed at 535 nm while for the dye 2, highest IPCE value observed was 20% at 620 nm.     

Photoelectrochemical studies on galvanostatically formed cadmium selenide films using mixed solvents

Galvanostatic deposition technique has been used for the formation of cadmium selenide films using water and dimethyl sulphoxide mixtures of variable composition. For photoelectrochemical characterization of these electrodeposits, photoelectroconvertibility and photoaction spectral studies have been carried out using I₂/I₃⁻ and [Fe(CN)₆]⁻³/[Fe(CN)₆]⁻⁴ redox systems. Resistance of these photoelectroactive films towards electrochemical corrosion has also been investigated on the basis of current–voltage studies using Tafel plots.     

On the use of triethylamine hydroiodide as a supporting electrolyte in dye-sensitized solar cells

For the first time, the application of a molten salt, triethylamine hydroiodide (THI), as a supporting electrolyte was investigated for the dye-sensitized solar cells (DSSCs). Titanium dioxide (TiO₂) electrode was modified by incorporation of high- and low-molecular weight poly(ethylene glycol) along with TiO₂ nanoparticles of two different sizes (300 nm (30 wt%) and 20 nm (70 wt%)). The highest apparent diffusion coefficient (D) of 8.12×10⁻⁶ cm² s⁻¹ was obtained for I⁻ (0.5 M of THI) from linear sweep voltammetry (LSV). Short-circuit current density (J_sc) increases with the concentration of THI whereas open-circuit potential (V_oc) remains the same. Optimum J_sc (19.28 mA cm⁻²) and V_oc (0.7 V) with a highest conversion efficiency (η) of 8.45% were obtained for the DSSC containing 0.5 M of THI/0.05 M I₂/0.5 M TBP in CH₃CN. It is also observed that the J_sc and η of the DSSC mainly relates with the D values of I⁻ and charge-transfer resistances such as R_ct1 and R_ct2 operating along Pt/TiO₂ electrolyte interface, obtained from LSV and electrochemical impedance spectroscopy (EIS). For comparison, tetraethylammonium iodide (TEAI) and LiI were also selected as supporting electrolytes. Though both the THI and TEAI have similar structures, replacement of one methyl group by hydrogen improves the efficiency of the DSSC containing the former electrolyte. Further, the DSSC containing THI exhibits higher J_sc and η than LiI (7.70%), from which it is concluded that THI may be used as an efficient and alternative candidate to replace LiI in the current research of DSSCs.     

A novel activated mesocarbon microbead(aMCMB)/Mn3O4 composite for electrochemical capacitors in organic electrolyte

A novel activated mesocarbon microbead(aMCMB)/Mn₃O₄ composite is successfully prepared for electrochemical capacitors. The morphology and crystal structure of the composite are investigated by scanning electron microscopy and X-ray diffraction. The electrochemical studies indicate that the aMCMB/Mn₃O₄ composite has ideal capacitive performance in 1.0 mol L⁻¹ LiPF₆(EC + DMC). A maximum specific capacitance of 178 F g⁻¹ is obtained for the composite via galvanostatic charge–discharge at a current density of 330 mA g⁻¹, and the specific capacitance of Mn₃O₄ is estimated to be as high as 445 F g⁻¹. The aMCMB/Mn₃O₄ composite material exhibits ideal capacitive behavior indicating a promising electrode material for electrochemical supercapacitors.     

Synthesis and photovoltaic properties of novel PPV-derivatives tethered with spiro-bifluorene unit for polymer solar cells

New thermally robust photoactive arylenevinylene-based conjugated polymers, poly[3,6-bis(3,7-dimethyloctyloxy)-9,9-spirobifluorenyl-2,7-vinylene] [(OC₁₀)₂-spiro-PFV] and poly[{3,6-bis(3,7-dimethyloctyloxy)-9,9-spirobifluorenyl-2,7-vinylene}-co-2-{methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene}] [(OC₁₀)₂-spiro-PFV-co-MEH-PPV], were synthesized and used to fabricate polymer solar cells. Bulk heterojunction solar cells fabricated by blending the new copolymers, spiro-PFV and (OC₁₀)₂-spiro-PFV-co-MEH-PPV, as an electron donor with the fullerene derivative, [6,6]-phenyl C₆₁ butyric acid methyl ester (PCBM) as an electron acceptor. The effects of electron donor to acceptor ratio, thickness of photoactive layer, and the cathode structures on the power conversion efficiency (PCE) in polymer solar cells were studied. The copolymer feed ratio was found to have a considerable effect on the PCE. The maximum PCE of 1.30% was achieved with (OC₁₀)₂-spiro-PFV-co-MEH-PPV.     

An EQCM study for a novel aromatic poly(amine-imide) electrochromic thin film

A new aromatic poly(amine-imide) electrochromic thin film synthesized with N,N-bis(4-aminophenyl)-N′,N′-diphenyl-1,4-phenylenediamine and 3,3′,4,4′-benzo-phenonetetra carboxylic dianhydride, abbreviated as poly(PD-BCD), was studied. The poly(PD-BCD) thin-film electrode has been characterized by cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM). As the polymer chain acquires positive charge during the oxidation of poly(PD-BCD) to its radical cation state or dication state, the anions would insert into the polymer matrix in order to neutralize the charge. However, when the electrodes were cycled in electrolytes containing different cations, including 0.1 M LiClO₄/acetonitrile (ACN), 0.1 M NaClO₄/ACN and 0.1 M TBAClO₄/ACN, the experimental results revealed two mechanisms for the redox reaction. A plot of mass change (Δm) vs. accumulated charge (Q) gave a slope, from which the electrochromic mechanism can be extracted. The slopes of Δm–Q obtained from the CV–EQCM measurements in three electrolytes were different for the first redox stage, but the slopes were almost the same for the second redox stage. This means that, in addition to the involvement of anions, cations also play an important role in the first redox stage, however, the role of the cations is less in the second stage. Moreover, two reaction mechanisms for the two reaction stages of poly(PD-BCD) are proposed in this study.     

Behavior of single chambered mediatorless microbial fuel cell (MFC) at acidophilic, neutral and alkaline microenvironments during chemical wastewater treatment

Single chamber mediatorless microbial fuel cell (MFC; non-catalyzed graphite electrodes; open air cathode) behaviour was evaluated under different pH microenvironments [acidophilic (pH 6), neutral (pH 7) and alkaline (pH 8)] during chemical wastewater treatment employing anaerobic mixed consortia as anodic biocatalyst at room temperature (29 ± 2 °C). The performance was found to depend on the feed pH used. Higher current density was observed at acidophilic conditions [pH 6; 186.34 mA/m²; 100 Ω] compared to neutral [pH 7; 146.00 mA/m²; 100 Ω] and alkaline [pH 8; 135.23 mA/m²; 100 Ω]. On the contrary, substrate degradation was found to be effective at neutral pH conditions (ξ_COD – 58.98%; SDR – 0.67 kg COD/m³-day) followed by alkaline (ξ_COD – 55.76%; SDR – 0.62 kg COD/m³-day) and acidophilic (ξ_COD of 47.80%; SDR 0.58 kg COD/m³-day) conditions studied. However, relatively higher specific power yield was observed at acidophilic microenvironment (46 mW/kg COD_R) compared to neutral (35 mW/kg COD_R) and alkaline (34 mW/kg COD_R) conditions. The behaviour of the MFC was also evaluated employing electron discharge, cyclic voltammetry, cell potentials, Coulombic efficiency and sustainable power analysis. Acidophilic operation showed higher Coulombic efficiency and effective electron discharge at relatively higher resistance compared to neutral and alkaline conditions studied.     

Self-assembled synthesis of hierarchical nanostructured CuO with various morphologies and their application as anodes for lithium ion batteries

We report a simple self-assembled synthesis of hierarchical CuO particles with various morphologies such as leaf, shuttle, flower, dandelion, and caddice clew. The morphologies can be easily tailored by adjusting the pH value. The synthesis is based on dehydration and re-crystallization of precursor Cu(OH)₂ nanowires. [Cu(NH₃)₄]²⁺ and OH⁻ in the solutions are considered as the key factors to influence the assembling manner of CuO. The obtained hierarchical CuO particles serve as a good model system for the study as anodes for lithium ion batteries. Various morphologies of CuO particles result in different electrochemical performances of electrodes. Compared to others, dandelion-like and caddice clew-like CuO exhibit reversible discharge capacities of 385 mAh g⁻¹ and 400 mAh g⁻¹ at 0.1 C, 340 mAh g⁻¹ and 374 mAh g⁻¹ at 0.5 C after 50 cycles, respectively. The higher discharge capacities and better cycling performances are attributed to their larger surface area and porosity, leading to better contact between CuO and electrolyte and shorter diffusion length of lithium ions.