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LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode materials can operate at extremely high voltages and have exceptional energy density. However, their use is limited by inherent structure instability during charge/discharge and exceptionally oxidizing Ni4+ at the surface. Herein, we have developed a citrate-assisted deposition concept to achieve a uniform lithium-conductive LiNbO3 coating layer on the NCM523 surface that avoids self-nucleation of Nb-contained compounds in solution reaction. The electrode–electrolyte interface is therefore stabilized by physically blocking the detrimental parasitic reactions and Ni4+ dissolution whilst still maintaining high Li+ conductivity. Consequently, the modified NCM523 exhibits an encouraging Li-storage specific capacity of 207.4 mAh g−1 at 0.2C and 128.9 mAh g−1 at 10C over the range 3.0–4.5 V. Additionally, a 92% capacity retention was obtained after 100 cycles at 1C, much higher than that of the pristine NCM523 (73%). This surface engineering strategy can be extended to modify other Ni-rich cathode materials with durable electrochemical performances.

The efficiency of tandem pn-dye-sensitized solar cells (pn-DSCs) has been limited by the poor performance of the available p-DSCs. A facile approach of introducing a compact NiO blocking layer into an active NiO photocathode network of p-DSCs and pn-DSCs is presented to enrich the power conversion efficiency (PCE) using a Co2+/3+ redox mediator. Two photoelectrodes sensitized with different dyes (SQ for n-DSC and P1 for p-DSC) have a complementary nature in absorbing solar irradiation at different wavelengths. The constructed pn-DSC demonstrates an enhanced photovoltage compared to n-DSC, resulting in an overall PCE of 1.486%. This PCE is further improved to 1.913% by the addition of an optimized NiO blocking layer to the p-DSC; this was prepared via spin-coating with a nickel acetate precursor solution. All photovoltaic parameters were significantly increased with the introduction of a blocking layer compared to a bare cell.

In this paper, we have studied the effect of LiI and I2 concentrations on the photovoltaic properties of dye-sensitized solar cells (DSSCs) based on NiO. For all concentrations of iodine, the photo...

Metal-organic frameworks (MOFs) have lately obtained great attention of scientists as potential materials applied for supercapacitor electrodes. Due to their crystalline structure, MOFs show proper electrochemical double-layer capacitance at the enlarged specific surface area of the material and the mechanical supports for the composite materials. In this study, Zn-MOF was synthesized and composited with reduced graphene oxide (rGO) to be applied as a supercapacitor electrode material. To improve the electrodes working performance, polyaniline (PANI) was synthesized by different methods and added to the composite. The electrochemical properties of these materials were studied to identify the effect of PANI and Zn-MOF on the electrode materials. Among the composites obtained, the best specific capacitance of about 372 F/g was obtained at 0.1 A/g charge-discharge analysis of rGO/Zn-MOF@PANI sample due to its large surface with high pores sizes. The capacitance retentions of electrodes were also tested to decipher the effect caused by varied composites fabrication.

The introduction of different thicknesses of a compact NiO blocking layer coating with different spin speeds on FTO and followed by a coating of photoactive NiO electrode for p-type dye-sensitized solar cells (p-DSCs). This study examined the fabrication of a compact NiO blocking layer by decomposing an ethanolic precursor solution of nickel acetate tetrahydrate. The DCBZ dye used as the photosensitizer for the NiO electrode in the p-DSCs device and their performances have been analyzed. The enhancement of photovoltaic performance and resulted from an increase in the power conversion efficiency (η). The electrochemical impedance spectroscopy (EIS) measurement demonstrated that charge recombination was suppressed when a compact NiO blocking layer was applied. The results showed that the best p-DSC was achieved by employing 3000 rpm spin-coated process for different times of blocking layer.

A photoactive NiO electrode for p-type dye-sensitized solar cells (p-DSCs) has been equipped by the introduction of different coatings of a compact NiO blocking layer. This study examined the facile process for the fabrication of a compact NiO blocking layer by decomposing an ethanolic precursor solution of nickel acetate tetrahydrate. The P 1 -dye used as the photosensitizer for the NiO electrode in the p-DSCs device and their performances have been analyzed. The enhancement of both short-circuit photocurrent (Jsc) and fill factor (FF) resulted in a twofold increase in the power conversion efficiency (η). The electrochemical impedance spectroscopy (EIS) and open-circuit voltage decay (OCVD) measurements demonstrated that charge recombination was suppressed when a compact NiO blocking layer was applied. The best p-DSC was achieved by employing spin-coated process for twice. The carrier lifetime of all the devices with a compact NiO blocking layer was improved compared to the bare cell.

Polymer nanocomposites that based on combination of nanomaterials (such as nanoparticles, nanotubes, nanorods, nanofibers, and nanosheets) and polymeric matrices are receiving great attention in research and application. However, separate and homogenous dispersion rather than aggregates of nanoparticles into matrices meet big difficulty due to large interaction between nanoparticles. The poor dispersion leads to low properties of nanocomposites. In this study, we find out the appropriate method to separately disperse cerium oxides (CeO2) nanoparticles into natural rubber, aiming to increase mechanical properties of natural rubber. The SEM images were used to evaluate the dispersion of nano CeO2 in natural rubber matrix. The mechanical properties of nanocomposites were measured after vulcanization to investigate effects of nano CeO2 amount on prepared composite. The findings exhibited that the addition of CeO2 by dispersion of nano CeO2 in water via ultrasonication before mixing with rubber latex, signific...

Two new ullazine-based organic dyes have been synthesized for applications in nanocrystalline TiO2-based dye-sensitized solar cells (DSSCs). Overall conversion efficiencies up to 3.63% were obtained for DSSCs based on these dyes. The dye with a tert-butyl antenna exhibited a higher and redshifted absorption pattern resulting in increased light-harvesting property. Compared to the unsubstituted dye, the photocurrent density, open-circuit photovoltage and overall power conversion efficiency (PCE) of solar cells based on the tert-butyl substituted dye are improved. The decreased PCE of the solar cell based on unsubstituted dye results mainly from the increased recombination rate and decreased electron lifetime, as evidenced from impedance and photovoltage decay measurements. Density functional theory (DFT) and time-dependent DFT calculations were performed to predict the geometries, electronic structure, and the optical and electrochemical properties of the dyes.

Two simple organic dyes (J1 and J2) containing julolidine as the electron donor were synthesized. The simple structure of julolidine attached to the cyanoacetic acid group formed two compounds (anion and neutral forms of E-CCVJ), which showed two different efficiencies when applied to dye-sensitized solar cells (DSSCs). Overall conversion efficiencies of 0.91% and 1.21% were obtained for DSSCs based on the cyanoacetic acid (J1) and cyanoacetate (J2) derived dyes, respectively. Compared to the cyanoacetic acid terminated dye, the current density, open circuit voltage and conversion efficiency of the solar cells based on cyanoacetate dye were increased by approximately 24%, 8% and 32%, respectively. The electrochemical impedance analysis showed that the better charge transfer of TiO2 (e-) and electron lifetime (τ(e)) for J2 dye as compared with J1. The power conversion efficiency was found to be quite sensitive to small structural changes to the anchoring moiety.