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The electronic structures and optical properties of La, C-codoped TiO2 were investigated by the first-principles plane-wave ultrasoft pseudopotential method. Our calculations suggest that the micro-structures of La-C codoped system is different from that of TiO2, and the hole effective mass is increased by La-doping, which can create holes in the valence band; Nonmetal C doping can narrow the band gap of TiO2 and enhance the photo-catalytic activity by the formation of localized mid-gap state originated from C 2p states above the top of the valence band; Metal La and nonmetal C co-doping could induce a synergistic effect, the doping of La atoms leads the redistribution of C 2p states in C atoms, which provide more electrons to participate into the 3d states of Ti atoms. The charge compensation effects between Ti 3d and C 2p produce impurity levels, which reduce the band gaps and enhance the carrier concentration, meanwhile La ions are not easy to enter the lattice of TiO2, which may form hetero-junction structure of La2O3-TiO2 with better dispersion in the bulk phase of TiO2 to limit the recombination of photo-generated electron hole pairs. The calculated results of optical properties show that C-TiO2 and La-C-TiO2 systems exhibit good visible absorption and the doping is beneficial to the propagation of light in the doped TiO2.

A room temperature based environmentally friendly aqueous solution synthesis route was developed to fabricate highly dispersed small SnO2 nanoparticles (3–5 nm) without the application of any pressurized reaction vessel or organic solvents. The subsequent treatments, that is, dialyzing and freezing, allow for the acquision of dual-function nanostructures with sheet-like feature and large aspect ratio except for the ordinary irregular aggregates. Dye-sensitized solar cells (DSCs) constructed with the resultant multifunctional SnO2 showed an outstanding photovoltaic conversion efficiency (PCE) of 6.92% and an unexpected JSC of 19.5 mA cm–2 at an optimized thickness of 14.1 μm. The excellent performance can be ascribed to the effective coordination of the favorable features (i.e., strong light scattering, large dye loading capability, and fast electron transport) via rational film thickness control as indicated by diffused reflectance spectra, UV–vis absorption spectra, and electrochemical impedance spectros...

Multishell, stable, porous metal-oxide microspheres (Ni–Co oxides, Co3O4 and NiO) have been synthesized through the amorphous coordination polymer-based self-templated method. Both oxides of Ni and Co show poor selectivity to xylene, but the composite phase has substantial selectivity (e.g., Sxylene/Sethanol = 2.69) and remarkable sensitivity (11.5–5 ppm xylene at 255 °C). The short response and recovery times (6 and 9 s), excellent humidity-resistance performance (with coefficient of variation = 11.4%), good cyclability, and long-term stability (sensitivity attenuation of ∼9.5% after 30 days and stable sensitivity thereafter) all show that this composite is a competitive solution to the problem of xylene sensing. The sensing performances are evidently due to the high specific surface area and the nano-heterostructure in the composite phase.

In this work, we concentrate on the investigation of the fundamental effects of annealing temperatures on the synthesized polydisperse of ZnO aggregates for the exploration of effective electrode material for dye-sensitized solar cells (DSCs). Systematic characterizations including TEM, SEM, BET analysis, XRD, and r-PL were performed for the ZnO aggregates annealed at various temperatures, and the results revealed that the morphology of aggregates, crystal size of primary particle, crystallinity, specific surface areas and the surface states largely depends on the annealing temperature. The photoelectrical efficiency tests demonstrated that the ZnO aggregates annealed at 450 °C exhibited the highest efficiency of 5.10%. The excellent performance could mainly originate from the more efficient light harvesting property of the resulted ZnO photoanode indicated by the incident photon-to-current efficiency (IPCE) and the accelerated electron transport within the ZnO film testified by electrochemical impedance spectroscopy (EIS). Moreover, the combination of the composition control with the introduction of both a ZnO compact layer (CL) and a TiO 2 protecting layer (PL) was simultaneously integrated into one photoanode film for the first time. As a consequence, an impressive power conversion efficiency of 5.83% was achieved with the new photoanode architecture, an improvement of 39.5% over the unmodified DSC. The synergistically reduced charge-transport resistance and suppressed electron recombination are regarded to be the key element for outstanding performance.

The task of control synthesis of Markovian jump nonlinear system is well investigated through giving a new fuzzy switching controller aiming at easing the conservatism than before. Compared with previous results, less conservative stabilization conditions for the considered discrete-time Markovian jump fuzzy system can be gained which lead to wider application of the proposed theoretical method. In the analysis and derivation process, some important information hidden in the fuzzy basis function is well utilized and thus a new scheme of fuzzy switching control law is presented to reduce the conservatism that is caused by ignoring those important information hidden in the fuzzy basis function in the literature. Finally, the validity and advantage of the proposed method over the recent one is also demonstrated by controlling an inverted pendulum model.

Iodine doped TiO2 with different iodine/Ti molar ratios has been firstly synthesized with a low temperature hydrothermal route and has been studied systematically in photocatalysis under visible light condition. The resulting iodine doped TiO2 were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (TEM), diffuse reflectance spectrum (DRS), and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance investigations were conducted by means of the degradation of Rhodamine B (RhB) under the visible light irradiation in aqueous solution. Under an optimized I/Ti doping ratio of 10 mol%, the photocatalytic performance is greatly better, with degradation efficiency of 95%, which is almost double that of pure TiO2. The superior photocatalytic activity of iodine-doped TiO2 could be mainly attributed to extended visible light absorption originated from the formation of continuous states existed in the band gap of the doped TiO2 introduced by iodine. Active oxygen species, that is, (OH)-O-center dot and O-2(-), were evidenced to be involved in the degradation process and a possible mechanism was also proposed.

The hetero-junctions of LaMnO3 and g-C3N4 nano-materials are expected to have suitable band structure for the Z-scheme mechanism, but the electronic structures and interfaces have been scarcely studied. In this work, g-C3N4/LaMnO3 hetero-junction composed of g-C3N4 and LaMnO3 layers is studied using the DFT calculations with plane-wave ultrasoft pseudopotential basis sets. The calculated g-C3N4/LaMnO3 heterostructure has a small lattice-mismatch compared with LaMnO3 and g-C3N4. There are reformed Mn-N bonds across the interface, which indicates the strong interaction existing in two layers between LaMnO3 and g-C3N4. When g-C3N4 and LaMnO3 are in contact, the electrons will transfer from LaMnO3 layer to g-C3N4 layer. On the basis of the band structure analysis, the photo-generated electrons in LaMnO3 can combine with the photo-induced holes in g-C3N4, which leads the higher reduction ability of photo-generated electrons in g-C3N4, and the stronger oxidation of photo-induced holes in LaMnO3. As a result, the Z-scheme heterojunction could be generated between the g-C3N4 layer and LaMnO3 layer, which not only has the better visible light adsorption capability, but also the more efficient charge carrier separation.

Fe-Doped NiO multi-shelled microspheres have been synthesized via a facile hydrothermal reaction. Various characterization techniques were introduced to investigate the structure and morphology of the as-prepared Fe-doped NiO multi-shelled microspheres. SEM and TEM observations showed that NiO microspheres are about 500 nm in diameter and with three shells. The Fe-doped NiO multi-shelled microspheres were investigated systematically as gas sensing materials for chemiresistive semiconductor-based gas sensors. The results showed that the 1.92 at% Fe-doped NiO (1.92Fe-NiO) multi-shelled microspheres exhibited enhanced gas sensing performance compared to the pure NiO multi-shelled microspheres. The gas response of 1.92Fe-NiO multi-shelled microspheres to 100 ppm butanol was 45.1 at 140 °C, which revealed a remarkable improvement over the pure NiO multi-shelled microspheres (6.80). The increased response of 1.92Fe-NiO multi-shelled microspheres may be attributed to the incorporation of Fe ions into NiO nanocrystals, which adjusted the carrier concentration and caused an increase in the oxygen species on the adsorbed surface. Therefore, the Fe-doped NiO multi-shelled microspheres should be a promising material for high performance butanol gas sensors.

Both pure and Mn(II)-doped ZnO hollow structures were synthesized by a solvothermal reaction, and their phase structures, morphologies and elemental composition were characterized. SEM and TEM observations show the pure ZnO and the Mn(II)-doped ZnO balls to possess similar hollow structure with a particle size of about 1.5 μm. Their sensing properties were investigated, and the composite containing 1 atom% of Mn(II) (1% Mn-ZnO) is found be display the highest selectivity for acetone. The detection limit is 100 ppm acetone at 234 °C which is 4.6 times lower than that of the pure ZnO. In addition, the response time is shorter. Graphical abstract ZnO and Mn-doped ZnO hollow balls were prepared by a hydrothermal method, and their gas-sensing properties were investigated. Zinc(II) oxide doped with 1 atom% Mn(II) demonstrated an outstanding sensing behavior towards acetone vapors.

Hierarchical SnO2 nanocrystallites aggregates (NAs) were prepared with a simple room temperature&ndash, based aqueous solution method followed by simple freeze-drying treatment. The as-prepared SnO2 NAs were subsequently combined with SnO2 nanosheet&ndash, based structures from the viewpoint of a function-matching strategy, and under an optimized condition, a power conversion efficiency (PCE) of 5.59% was obtained for the resultant hybrid photoanode, a remarkable 60% enhancement compared to that of dye-sensitized solar cells (DSCs) fabricated with bare SnO2 NAs architecture. The significantly enhanced efficiency can be attributed to the combination of the desirable electron transport property obtained by the intentionally introduced SnO2 nanosheets (NSs) and the effectively retained inherent characteristics of SnO2 NAs, i.e., large surface area and strong light-scattering effect. This work provides a promising approach for the rapid development of highly efficient SnO2 photoanode film-based DSCs with the properties of simplicity of operation and control over the photoanode composition.