Polarized Thin Layer Deposited Electrochemically on Aluminum-Doped Zinc Oxide as a Cathode Interlayer for Highly Efficient Organic Electronics

An Electrochemical Sensor Based on Electropolymerization of β-Cyclodextrin on Glassy Carbon Electrode for the Determination of Fenitrothion

An electrochemical sensor enabled by electropolymerization (EP) of β-cyclodextrin on glassy carbon electrode (β-CDP/GCE) is built for the determination of fenitrothion (FNT). The effects of the EP cycles, pH value, and enrichment time on the electrochemical response of FNT were studied. With the optimum conditions, good linear relationships between the current of the reduction peak of the nitroso derivative of FNT and the concentration are obtained in the range of 10-150 and 150-4000 ng/mL, with a detection limit of 6 ng/mL (S/N = 3). β-CDP/GCE also exhibits a satisfactory applicability in cabbage and tap water, with recovery values between 98.43% and 112%. These outstanding results suggest that β-CDP/GCE could be a new effective alternative for the determination of FNT in real samples.

Enhanced Long-Term Stability of Organic Electrode Materials by a Trap Filler Strategy

The sensitivity of organic electrode materials to water and oxygen has long been the bottleneck of their further development. The residual and penetrative water and oxygen in electrochemical cells form electron traps that trigger irreversible side reactions, which is detrimental to their long-term stability. A trap filler strategy by introducing molecules with low ionization energy in a cell, bis(pentamethylcyclopentadienyl)cobalt(II) (DMC) as an example, is demonstrated to deactivate traps spontaneously by donating electrons to traps without causing undesirable reactions with electrode materials. The electrode materials BthCz and AQCz, with lowest unoccupied molecular orbital levels above or near the electron traps (-3.6 to -3.8 eV), exhibit conspicuous stability increment of 68.6 and 26.3%, respectively, with the optimized DMC concentration of 5 × 10^-4 M in acetonitrile electrolyte.

Stabilization of a Cyclometalated Ruthenium Sensitizer on Nanocrystalline TiO2 by an Electrodeposited Covalent Layer

A cyclometalated ruthenium sensitizer 3 containing a triphenylamine unit was synthesized and immobilized on a nanocrystalline TiO₂ surface. By using oxidative electrochemical deposition, a covalent layer of a related cyclometalated ruthenium complex 2 was coupled to the top of dye 3. Electrochemical studies suggested that complex 2 was immobilized on the TiO₂/3 film surface by a tetraphenylbenzidine linker to form a dimer-like structure. The immobilization of 3 and 2 was further supported by absorption spectral analysis. The resulting electrodeposited TiO₂/(3+2) film displays significantly enhanced sensitizer stabilization toward basic aqueous NaOH solution with respect to the original TiO₂/3 film. The dye-sensitized solar cells with the TiO₂/(3+2) photoanode display a power conversion efficiency of 4.4%, which is slightly inferior to that with the TiO₂/3 film (5.1%) under the same measurement conditions.

Nanocrystalline Sb-doped SnO2 films modified with cyclometalated ruthenium complexes for two-step electrochromism

Sb-Doped nanocrystalline SnO2 (SnO2:Sb) thin films functionalized with cyclometalated ruthenium complexes 1 or 2 on FTO conductive glasses have been prepared and characterized. These complexes contain a redox-active amine unit separated from the ruthenium ion by a phenyl or biphenyl linker, respectively, to modify the absorption wavelengths at different redox states. Near-infrared electrochromism of both films has been examined by oxidative spectroelectrochemical measurements and double-potential-step chronoamperometry. A contrast ratio (ΔT%) of 33% at 1070 nm and 63% at 696 nm has been achieved for the SnO2:Sb/1 film in two stepwise oxidation processes, respectively. The other film with complex 2 shows two-step electrochromism at 1310 and 806 nm with ΔT% of 36% and 76%, respectively. The response time of electrochromic switching is around a few seconds. Taking advantage of the good contrast ratio, the rapid response, and the long retention time of each oxidation state, these films have been successfully used to demonstrate surface-confined flip-flop memory functions with a high ON/OFF ratio.

Preparation and characterization of CS/β-CD/Nano-ZnO composite porous membrane optimized by Box-Behnken for the adsorption of Congo red

In this paper, an effective chitosan/beta-cyclodextrin/nanometer zinc oxide (CS/β-CD/Nano-ZnO) composite porous membrane was synthesized by sol-gel and polymer-assisted inverting method. Preparation conditions of CS/β-CD/Nano-ZnO were investigated by single-factor and Box-Behnken response surface methodology optimizing triethoxyvinylsilane (JH-V151), beta-cyclodextrin (β-CD), and nanometer zinc oxide (Nano-ZnO), and applied to study the adsorption characteristics of Cong red (CR) from aqueous solution using batch experiments. The optimum preparation conditions were determined that the volume fraction of JH-V151 alcohol solution was 11%, the ratio of β-CD to CS was 5.35, and the ratio of Nano-ZnO's mass to solution's volume was 0.36%. Different characterization methods including field-emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, UV-visible spectroscopy, and Universal Materials Tester were used to prove the appearance, crystallinity, functional groups, swelling degree, transmittance, and tensile property of CS/β-CD/Nano-ZnO. The optimized batch experimental parameters were 50 mg L^-1, 4 h, 7.0, 0.5 g L^-1, and 55.0 °C as initial concentration, contact time, pH, adsorbent dose, and temperature, respectively. The maximum adsorption capacity on CR reached 96.33 mg g^-1, which is 4.34 times with respect to CS. The batch experimental data were best described by a pseudo-second-order kinetics model and Langmuir isotherm model (R² = 0.9965, theoretical saturated adsorption capacity 147.28 mg g^-1). The values ∆G were - 2.09, - 4.73, and - 7.37 kJ mol^-1 at 298, 308, and 318 K temperatures, respectively. The ∆H value was 76.68 kJ mol^-1, indicating the endothermic and spontaneous adsorption in nature. The ∆S value was 0.26 kJ mol^-1 K^-1, a signal of entropy increase during adsorption. The adsorption capacity decreased only by 5.8% after six recycling runs, which indicated the reusability of CS/β-CD/Nano-ZnO. Therefore, the CS/β-CD/Nano-ZnO composite porous membrane is a promising membrane material for the efficient removal of CR from any water at large and economic scales at moderate concentration.

Construction of Layered Structure of Anion-Cations To Tune the Work Function of Aluminum-Doped Zinc Oxide for Inverted Polymer Solar Cells

Suitable work function (WF) of the cathode in polymer solar cells (PSCs) is of essential importance for the efficient electron extraction and collection to boost the power conversion efficiency. Herein, we report a facile and efficient method to tune the surface WF of aluminum-doped zinc oxide (AZO) through building of a definite interfacial dipole, which is realized by the construction of a layered structure of positive and negative ionized species. A cross-linked perylene bisimide (poly-PBI) thin film is deposited onto the AZO surface first, and then it is reduced to the radical anion state (poly-PBI^•-) in an electrochemical cell, using tetraoctylammonium (TOA⁺), a bulky cation, as a counter ion. Owing to the huge volume of TOA⁺, it is absorbed on the surface of the cross-linked PBI^•- thin film through Coulomb force, and thus a definite interface dipole is formed between the two ionized layers. Because of the definite interface dipole, the surface WF of the electrode modified with ionized layers is decreased dramatically to 3.9 eV, which is much lower than that of the electrode modified with the neutral PBI layer (4.5 eV). By using this novel cathode interlayer with a definite interface dipole in PSCs, a significantly increased open-circuit voltage ( V_OC) is obtained. The results indicate that it is a facile and unique method by the construction of a definite interface dipole to tune the surface WF of the electrode for the application in organic electronic devices.