[en] Graphical abstract: Photocatalytic activities (a) and fitting curves (b) and recyclability (c) of Ag_3PO_4 MPs annealed at various temperature (RT-500 °C) under a visible-light irradiation. - Highlights: • Ag_3PO_4 microparticles were sintered in air at various temperatures from 100 to 500 °C. • Sintering leaded to the aggregation of Ag_3PO_4 microparticles, while it didn’t descend the photocatalytic activity significantly. • The best photocatalytic activity appeared in the samples which underwent 400 °C sintering for 30 min. • The enhanced photocatalytic activity of the 400 °C sintered samples was attributed to the enhanced carrier transport and the improved crystallized quality. - Abstract: Ag_3PO_4 microparticles (MPs) were annealed in air at various temperatures (100–500 °C) and time (30–120 min). It is surprising that both the phase structure and photocatalytic (PC) activities didn’t descend even if the powders samples were annealed at 400 °C for 30 min, which made it possible to obtain Ag_3PO_4 films similar to the common semiconductor photocatalysts, such as TiO_2. However, the particle sizes of MPs were observed to get increased significantly, resulting in a lowering of the specific surface area and a change of color. By excluding a few common causes, the excellent PC activities of the sintered samples are speculated to the improved crystallized quality, which also makes it possible to construct the photoelectrodes based on Ag_3PO_4 films for water splitting or photoelectric conversion.

[en] Photoelectrochemical (PEC) performance of Ag₃PO₄ microparticles (MPs) were evaluated by constructing a three-electrode cell with porous Ag₃PO₄ film as the photoanode. A simple grind-coating deposition route was developed to synthesize the Ag₃PO₄ films, which displayed excellent PEC activity and stability, even after a 400 °C or 500 °C annealing process. Excellent PEC performance was mainly attributed to a high adhesion between the film and substrate, and formation of a Ag₃PO₄/Ag junction. Moreover, n-type conduction behavior was identified by characterizing the Mott–Schottky (M–S) plots of a Ag₃PO₄ film synthesized via grind-coating. Finally, the grind-coating route was used for preparing the BiVO₄ film photoanodes, of which the PEC performance was compared with those of Ag₃PO₄ films.

[en] The power conversion efficiency of mesoporous perovskite solar cells (PSCs) is closely related with TiO₂ mesoporous layer. As the most universal mesoporous layer material, however, TiO₂ does weakly in electrical properties. As a result, structure modifications of TiO₂ mesoporous layer are required. In this work, niobium/tantalum doped TiO₂ mesoporous layer were prepared via a facile one-pot solution process, and applied successfully as high quality mesoporous layer for mesoporous PSCs. Performance of perovskite solar cells prepared with Nb/Ta-doped TiO₂ mesoporous layer enhanced apparently compared with the control device, especially in the short circuit current density (Jsc) which was improved from 18.4 to 21.3 mA cm⁻².

[en] Nickel oxide, a potential inorganic hole transport material, has become a research hot spot in perovskite solar cells. In this work, we propose a low temperature spray combustion method to fabricate NiOx thin film which has better performance compared with the spin-coating method. The SEM images of NiOx thin films by spraying exhibit denser morphology than films by spin-coating, demonstrating the feasibility of the spray combustion method. Based on this spray combustion method, Cu is doped into the NiOx precursor solution to further overcome the low conductivity of NiOx. When the doping concentration reaches to 7%, the efficiency of the solar cell is improved from 9.08 to 11.45%. The charge transfer process at NiOx/perovskite interface is investigated by PL and TRPL measurements, the results demonstrate the fast hole extraction using Cu:NiOx thin films. In summary, the spray combustion method can efficiently prepare high-quality Cu:NiOx thin films, reduce the annealing temperature and improve the conductivity of the thin film.

[en] Monte Carlo simulations were employed to study the argon adsorption on kaolinite surface with an experimental comparison. By (001) surface simulation, the low energy peak of isotherm derivative was clearly assigned to the hydroxyl surface, and the high energy peak to the basal oxygen surface. The monolayer adsorption mechanism and the adsorption sites were made according to the distribution and potential of argon on both (001) surface. By simulations of (100) and (010) lateral surfaces, and complete outer surface, the difference between (001) surface simulation and experimental results was clarified and a new destination for derivative peaks was proposed.

[en] Due to the characteristics of low cost, simple process and high conversion efficiency, perovskite solar cells have become a research hotspot in recent years. In the structure of perovskite solar cell, perovskite active film plays an important role in sunlight absorption and electron–hole pair generation. This work focused on improving the quality of perovskite film by solvent annealing of perovskite film prepared with two-step spin-coating method. We chose n-butanol, a solvent with high boiling point, as an additive in CH₃NH₃I/isopropanol solution to execute the solvent annealing process. UV–Vis absorption spectra exhibited an enhancement in the absorbance of perovskite films with solvent annealing process. X-ray diffraction and scanning electron microscope measurements indicated that perovskite film had larger grain size after solvent annealing, especially when n-butanol content reached to 2% in the mixed solvents. The photovoltaic performance of perovskite solar cell was improved from 13.50% to the optimized 14.81%. This solvent annealing process could restrain the fast evaporation of solvent in CH₃NH₃I solution which is beneficial for perovskite film growth. It is found that this method has certain significance for the quality improvement of the perovskite film.

[en] Deformation of constituent phases determines the mechanical properties of titanium alloys. To address this relationship, the deformation of primary α (α_p), secondary α plates (α_s) and residual β phase (β_r) in Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy was investigated based on the microstructure near fracture surface of uniaxial tensile samples. It is found that α_p is elongated and α_s mainly undergoes kinking deformation during tensile tests. The deformation of α_p is dominated by planar slipping, the deformation of α_s in colony is dominated by planar slipping and in basket weave is controlled by twin, planar slipping and dislocation tangling and the deformation of β_r is controlled by dislocation tangling. In the microstructure with high volume fraction of α_p (about 60%), the deformation amount of both α_p and α_s increases with the thickness of α_s, which increases the elongation of the alloy and changes the failure modes of α_p from fracture to boundary separation. In the microstructure with low volume fraction of α_p (19%) and long α_s, α_p has large deformation amount, while α_s with relative small deformation amount has large kinking region which increases the strength of the alloy. However, due to low volume fraction of α_p, its contribution to the ductility of alloy is limited and thus the elongation of the alloy is relatively small.

[en] In order to investigate the effect of protective scale formed by high-temperature preoxidation process on the low-temperature oxidation behavior of a MoSi₂-based composite, the oxidation experiment at 500 deg. C in air was performed by employing X-ray diffraction, scanning electron microscopy and thermo-gravimetric analysis. The results show that the preferred low-temperature oxidation/pest sites are the externally cylindrical face of the sample without high-temperature preoxidation treatment. With the prolonging of oxidation, the pest advances radially in cylinder sample. When the oxidation time reaches 288 h, the mass gain is arrived at 0.466 mg cm^-2. A glass protective scale is formed on the surface of material by high-temperature preoxidation treatment. The scale can play a role of barrier layer of oxygen. This results in a reduced rate of low-temperature oxidation, and the pest is restrained. When the oxidation has been for 288 h, the mass gain of high-temperature preoxidation sample is only -0.007 mg cm^-2, and the surface microstructure is still smooth, without undergoing the pest oxidation. High-temperature preoxidation treatment can effectively restrain the low-temperature oxidation behavior, and avoid the pest phenomenon of MoSi₂-based composite

[en] Bismuth oxyhalide (BiOX, X = F, Cl, Br, I) semiconductors exhibit excellent optoelectronic properties due to their special layered structure. However, the understanding of BiOX-based alloys and hybrids still keeps lacking. Here, BiOBr/BiOF hybrids were in situ synthesized by a facile hydrothermal method under the aid of cetyltrimethylammonium bromide (CTAB) surfactant. The influence of CTAB on the phase, morphology, light absorption and photocatalytic performance was investigated in detail. The results showed that the morphology gradually evolved from irregular microblock to nanoplate, and the band gap was obviously narrowed from 3.66 to 2.69 eV with the increase of CTAB. Importantly, BiOBr/BiOF hybrids markedly enhanced the light absorption and photocatalytic performance. The degradation efficiency towards methylene blue (MB) arrived at 93.2% within 80 min under UV–vis light irradiation, to be about three times higher than that of pure BiOF with 32.7% degradation efficiency. This work may provide a deep understanding for BiOX hybrids. (paper)

[en] Sol-gel TiO₂ films are prepared by the dip-coating method and the spin-coating method, and then annealing is performed at different temperatures. The structures, optical properties, surface morphologies, absorption and laser-induced damage threshold (LIDT) at 1064 nm and 12 ns of the films are investigated. The results show that the dip-coating method can be used to obtain a higher LIDT than the spin-coating method. When the annealing temperature increases from 80 ℃ to 120 ℃, the dip-coated film obtains a higher LIDT, whereas the spin-coated film obtains a lower LIDT. In addition, the damage morphology is a spalling pit for the dip-coated film annealed at 80 ℃. When the annealing temperature increases to 120 ℃, it shows a melting area. For both the spin-coated films annealed at different temperatures, the damage morphologies are the combination of spalling and melting. The differences in LIDT and damage morphologies of the films are discussed. (authors)