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Here we demonstrated an approach to increase performance of P3HT:TiO 2 solar cell either by electron deficient boron or electron rich bismuth doping into TiO 2 nanorods. The B doping increases the absorption, crystallinity and electron mobility of TiO 2 nanorods. The Bi-doped TiO 2 has higher J sc as compared with B-doped TiO 2 , mainly due to the improvement of electron density and increased absorption of TiO 2 nanorods. The devices were fabricated from TiO 2 nanorods being surface modified by organic dye W-4. The dye facilitates the bandgap alignment and compatibility between TiO 2 and P3HT. The power conversion efficiency of solar cell has been increased by 1.33 times and 1.30 times for Bi-doped TiO 2 and B-doped TiO 2 , respectively, as compared with that of as-synthesized TiO 2 . The results suggest the optical and electronic properties of TiO 2 can be tuned by various dopants to enhance the device performance.

Photocatalytic processes can be used to illustrate both solar energy conversion and environmental friendly applications. In this study, we synthesize several titanium dioxide–palladium (TiO 2 –Pd) based catalysts by wet impregnation method plus hydrogen-thermal reduction process in order to develop high-effective photocatalysts that can be easily produced even in industrial quantities. Moreover, we examine the effects of hydrogen-thermal reduction process on the photocatalytic performance of TiO 2 –Pd based catalysts. From X-ray photoelectron spectroscopy analysis, increasing the hydrogen reduction process time results in the decreasing of palladium ion (Pd 2 + ) and palladium oxide (PdO), but it causes the increasing of palladium (Pd) metal. The hydrogen reduction process is helpful for the preparation of TiO 2 –Pd based catalysts with high photocatalytic decomposition of organic dyes (the apparent reaction rate constant ~ 0.124 min − 1 under solar simulator irradiation) and excellent photocatalytic hydrogen production rate (~ 26,000 μmol/g·h under UV-B irradiation). The TiO 2 –Pd based catalysts prepared in this study exhibit high photocatalytic performance. They are also industrially relevant especially when the low cost of Pd metal is taken into consideration.

The reaction kinetics and formation mechanism of oriented attachment for shaped nanoparticles in solution are not well-understood. We present the reaction kinetics and formation mechanism of organic-capped anatase TiO2 nanorods in solution as a case study for the oriented attachment process using small-angle X-ray scattering (SAXS) and transmission electronic microscopy. The SAXS analysis qualitatively and quantitatively provides in-depth understanding of the mechanism, including the structural evolution, interparticle interaction, and spatial orientation of nanoparticles developed from nanodots to nanorods during the nucleation, isotropic, and anisotropic growth steps. The present study demonstrates the growth details of oriented attachment of nanoparticles in solution. An ordered lamellar structure in the solution is constructed by the balance of interaction forces among surface ligands, functional groups, and solvent molecules serving as a natural template. The template allows the alignment of spherica...

We have demonstrated BiFeO3 (BFO) as a potential bilayer electrolyte for 650 °C low temperature solid oxide fuel cell application. The stoichiometric perovskite BFO is synthesized by wet chemistry, calcined at 500 °C and sintered at 850 °C. The crystalline structure is confirmed by X-ray diffraction spectroscopy, the atomic ratios (Bi : Fe) of 1.02 and 1.00 are determined by X-ray energy dispersive spectroscopy and inductively coupled plasma-mass spectroscopy, respectively. The X-ray photoelectron spectroscopy analysis indicates the presence of oxygen vacancies which can partially reduce Fe3+ and result in relatively high dielectric constant (6252 at 100 kHz) and ionic conductivity (>10−2 S cm−1 at 650 °C). The BFO is coated with an yttria-stabilized zirconia (YSZ) protective layer to avoid hydrogen reduction of BFO. This bilayer electrolyte exhibits a 1.6 times increase in maximum power density as compared with pure YSZ when a Ni–YSZ anode and lanthanum strontium cobalt ferrite (LSCF) cathode are used in the fuel cell at 650 °C.

We report the development of low moisture permeation and transparent dense polyacrylate/silica nanocomposite material that can exhibit both superhydrophobic and oleophobic (omniphobic) properties. The material was prepared by a three-step process. The first step involved the preparation of UV polymerizable solventless hybrid resin and the fabrication of nanocomposite. The hybrid resin consisted of a mixture of acrylate monomer, initiator, and acrylate-modified different size silica nanoparticles. The second step was to roughen the surface of the nanocomposite with unique nanotexture by oxygen plasma. In the third step, we applied a low surface tension fluoro monolayer on the treated surface. The nanocomposite exhibits desired superhydrophobicity and oleophobicity with a water contact angle of 158.2° and n-1-octadecene contact angle of 128.5°, respectively; low moisture permeation of 1.44 g·mm/m(2)·day; and good transparency (greater than 82% at 450-800 nm for ~60 μm film). The material has potential applications in optoelectronic encapsulation, self-cleaning coating, etc.

The charge recombination rate in poly(3-hexyl thiophene)/TiO(2) nanorod solar cells is demonstrated to correlate to the morphology of the bulk heterojunction (BHJ) and the interfacial properties between poly(3-hexyl thiophene) (P3HT) and TiO(2). The recombination resistance is obtained in P3HT/TiO(2) nanorod devices by impedance spectroscopy. Surface morphology and phase separation of the bulk heterojunction are characterized by atomic force microscopy (AFM). The surface charge of bulk heterojunction is investigated by Kelvin probe force microscopy (KPFM). Lower charge recombination rate and lifetime have been observed for the charge carriers in appropriate heterostructures of hybrid P3HT/TiO(2) nanorod processed via high boiling point solvent and made of high molecular weight P3HT. Additionally, through surface modification on TiO(2) nan,orod, decreased recombination rate and longer charge carrier lifetime are obtained owing to creation of a barrier between the donor phases (P3HT) and the acceptor phases (TiO(2)). The effect of the film morphology of hybrid and interfacial properties on charge carrier recombination finally leads to different outcome of photovoltaic I-V characteristics. The BHJ fabricated from dye-modified TiO(2) blended with P3HT exhibits 2.6 times increase in power conversion efficiency due to the decrease of recombination rate by almost 2 orders of magnitude as compared with the BHJ made with unmodified TiO(2). In addition, the interface heterostructure, charge lifetime, and device efficiency of P3HT/TiO(2) nanorod solar cells are correlated.

Wurtzite-structure MgxZn1 − xO materials with five different compositions of x from 0 to 0.14 were grown on sapphire substrates by metalorganic chemical vapor deposition. It was found that increasing Mg content in the MgxZn1 − xO not only increased the band gap energy of the film but was also beneficial to the epitaxial growth of p-type MgxZn1 − xO without using any doping sources. In addition, the combined ultraviolet photoluminescence (PL) and Raman scattering spectra were measured with PL–Raman signals obtained together, showing a blue-shift of PL band and variation of resonant Raman multi-order longitudinal optical phonon modes with an increase of Mg content.

The well known fuzzy measures, λ-measure and P-measure, have only one formulaic solution, the former is not a closed form, and the later is not sensitive. An improved multivalent fuzzy measure with infinitely many solutions of closed form, called L-measure, is proposed by our previous work. In this paper, expend the L-measure for being more choice, and get an improved fuzzy measures, called “hth-order L-measure”, denoted as Lh-measure, and a new Choquet integral regression model based on this Lh-measure is also proposed. For evaluating the proposed regression models with different fuzzy measures, a real data experiment by using a 5-fold cross-validation mean square error (MSE) is conducted. The performances of Choquet integral regression models with fuzzy measure based on λ-measure, P-measure, L-measure and Lh-measure, respectively, a ridge regression model, and a multiple linear regression model are compared. Experimental result shows that the Choquet integral regression models with Lh-measure based on γ-support outperforms others forecasting models.

When the multicollinearity within independent variables occurs in the multiple regression models, its performance will always be poor. Replacing the above models with the ridge regression model is the traditional improved method. In our previous work, we found that, the Choquet integral regression model with R-measure based on the new support, gamma-support, proposed by us has the best performance than before. In this study, for finding the further improved model, we replaced R-measure with our new fuzzy measure, L-measure in Choquet integral regression model with the new support, gamma-support. For comparing the Choquet integral regression model with P-measure, lambda-measure, R-measure and L-measure based on two different fuzzy supports, V-support and gamma-support, respectively, the traditional multiple regression model and the ridge regression model, a real data experiment by using a 5-fold cross-validation mean square error (MSE) is conducted. Experimental result shows that the Choquet integral regression model with L-measure based on gamma-support has the best performance.

When the multicollinearity between independent variables occurs in the multiple regression models, its performance will always be poor. The traditional improved method which is always used is the ridge regression model. Recently, the Choquet integral regression model with fuzzy measure can further be exploited to improve this situation. In this study, we found that based on different fuzzy support, the Choquet integral regression model with the same fuzzy measure may have different performances, three kinds of fuzzy supports, C-support, V-support and gamma-support proposed by our work were considered. For evaluating the performances of the Choquet integral regression models with P-measure or lambda-measure based on above different fuzzy supports, a real data experiment by using a 5-fold cross-validation mean square error (MSE) is conducted. Experimental result shows that the Choquet integral regression model with lambda-measure based on gamma-support has the best performance.

High refractive index transparent nanocomposites have been developed by in situ polymerization of a precursor that contains functional monomers and surface modified anatase TiO2 nanoparticles for optoelectronic applications. The monomers are in the liquid form, so environmentally friendly solventless precursors can be prepared. The precursor can be processed into various shapes or thick films (>50 microns) of the nanocomposite. The relationships of the chemical structure of the organic matrix, nanoparticle content and dispersity with the refractive index, transparency, mechanical and thermal properties are systematically investigated. The refractive index, and mechanical and thermal properties of the nanocomposite are increased with increasing TiO2 content and aromatic structure in the organic matrix due to their rigid characteristics. The transparency of the nanocomposite is increased with increasing TiO2 content and dispersity. At the same loading of nanoparticles, the higher dispersity and the better transparency are due to the less extent of Rayleigh scattering. At 18 vol% (60 wt%) of TiO2, the acetic acid modified TiO2/poly(4-vinyl benzyl alcohol) nanocomposite has a refractive index of 1.73 and excellent transparency (>85% from 500 nm to 800 nm). The refractive index of the nanocomposite can be further increased to 1.77 by replacing aliphatic acetic acid modified TiO2 with aromatic phenyl acetic acid modified TiO2. The results of this work provide new knowledge and a new pathway to design a polymer based high refractive index material.

Conjugated polymers are promising materials for oxygen sensing owing to their specific interaction with oxygen molecules and also advantages of low cost, easy processing and room temperature operation. The present work for the first time demonstrates an oxygen sensing material of poly(3-hexylethiophene) (P3HT)–TiO2 nanorod hybrid thin film which reveals considerable improvement of sensing response as compared to the pristine P3HT film. The effects of hybrid composition and film thickness on sensing performance were systematically investigated. Kelvin probe force microscopy (KPFM) was employed to understand the mechanism of oxygen sensing including the control of surface morphologies and electronic properties by TiO2 incorporation. The hybrid material developed in this study is helpful in the advancement of room temperature oxygen sensing technology.

The poly(3-hexyl thiophene):TiO2 nanorod (P3HT:TiO2) solar cell has a better thermal stability than the P3HT:PCBM solar cell; however, the former has a lower power conversion efficiency (PCE) than the latter. We would like to enhance the PCE of P3HT:TiO2 solar cell by improving the electron mobility of anatase TiO2 nanorods. Two novel approaches: (1) ripening and (2) boron doping for TiO2 nanorods were explored. TiO2 nanorods were synthesized first by sol–gel process in the presence of an oleic acid surfactant at 98 °C for 10 h. The size of the TiO2 nanocrystal is about 35 nm in length and 5 nm in diameter. The insulating oleic acid on the TiO2 nanorods was replaced by pyridine (as-synthesized TiO2) for good compatibility and charge transport between P3HT and TiO2 in the application of hybrid P3HT:TiO2 nanorod solar cells. The crystallinity of the as-synthesized TiO2 nanorods was increased through ripening (120 °C, 24 h) by using an autoclave reactor while the size of the nanocrystals was not significantly changed. Boron doped TiO2 nanorods (B-doped TiO2) were synthesized using the same sol–gel process of as-synthesized TiO2 nanorods but by replacing 0.7 at.% Ti with B using boron n-butoxide instead of titanium tetraisopropoxide. The UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses indicate the B is present in TiO2 nanorods as substitutional defects which can be either Ti–O–B or O–Ti–B bonding, with a B 1 s binding energy of 192.1 eV. The ripening process is more effective at increasing the crystallinity of TiO2 nanorods than boron doping, as shown by XRD and Raman spectroscopy. The electron mobility of the TiO2 nanorods is improved from 6.21×10−5 to 2.33×10−4 (cm2 V−1 s) and 5.27×10−4 (cm2 V−1 s) for ripened TiO2 and B-doped TiO2, respectively, as compared with as-synthesized TiO2. The PCE of P3HT:TiO2 solar cells was increased by 1.31 times and 1.79 times under A. M. 1.5 illumination for ripened and B-doped TiO2, respectively, as compared with as-synthesized TiO2. The B-doped TiO2 has the highest mobility and PCE, mainly due to the presence of partially reduced Ti4+ by boron atom with delocalized electrons.