Facile Synthesis of a Multifunctional SnO2 Nanoparticles/Nanosheets Composite for Dye-Sensitized Solar Cells.

Synthesizing SnO2 composite nanostructures via a facile one-step method has been proven to be a great challenge. By adjusting operating variables, such as the reaction solution's pH and solvent type, several SnO2 nanostructures, in particular, a function-matching SnO2 hybrid structure composed of irregular zero-dimensional nanoparticles (NPs) and two-dimensional nanosheets (NSs), could be created. The as-prepared SnO2 composites were then characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), and diffuse reflectance spectroscopy (DRS) to determine their physical properties. Dye-sensitized solar cells (DSCs) constructed with the resultant multifunctional SnO2 NPs/NSs composite exhibited the highest overall power conversion efficiency (PCE) of 5.16% among all products with a corresponding short-circuit current density of 18.6 mA/cm2 and an open-circuit voltage of 0.626 V. The improved performance can be attributed to the combined effects of each component in the composite, i.e., the intentionally introduced nanosheets provide desired electron transport and enhanced light scattering capability, while the nanoparticles retain their large surface area for efficient dye absorption.

Self-Seeding Synthesis of Hierarchically Branched Rutile TiO2 for High-Efficiency Dye-Sensitized Solar Cells.

This study presents a unique and straightforward room temperature-based wet-chemical technique for the self-seeding preparation of three-dimensional (3D) hierarchically branched rutile TiO2, abbreviated HTs, employing titanate nanotubes as the precursor. In the course of the synthesis, spindle-like rutile TiO2 and the intermediate anatase phase were first obtained through a dissolution/precipitation/recrystallization process, with the former serving as the substrates and the latter as the nucleation precursor to growing the branches, which finally gave birth to the production of 3D HTs nanostructures. When the specifically created hierarchical TiO2 was used as the photoanode in dye-sensitized solar cells (DSCs), a significantly improved power conversion efficiency (PCE) of 8.32% was achieved, outperforming a typical TiO2 (P25) nanoparticle-based reference cell (η = 5.97%) under the same film thickness. The effective combination of robust light scattering, substantial dye loading, and fast electron transport for the HTs nanostructures is responsible for the remarkable performance.

Mesoporous Ti0.5Cr0.5N for trace H2S detection with excellent long-term stability.

Efficient, accurate and reliable detection and monitoring of H2S is of significance in a wide range of areas: industrial production, medical diagnosis, environmental monitoring, and health screening. However the rapid corrosion of commercial platinum-on-carbon (Pt/C) sensing electrodes in the presence of H2S presents a fundamental challenge for fuel cell gas sensors. Herein we report a solution to the issue through the design of a sensing electrode, which is based on Pt supported on mesoporous titanium chromium nitrides (Pt/Ti0.5Cr0.5N). Its desirable characteristics are due to its high electrochemical stability and strong metal-support interactions. The Pt/Ti0.5Cr0.5N-based sensors exhibit a much smaller attenuation (1.3%) in response to H2S than Pt/C-sensor (40%), after 2 months sensing test. Furthermore, the Pt/Ti0.5Cr0.5N-based sensors exhibit negligible cross response to other interfering gases compared with hydrogen sulfide. Results of density functional theory calculation also verify the excellent long-term stability and selectivity of the gas sensor. Our work hence points to a new sensing electrode system that offers a combination of high performance and stability for fuel-cell gas sensors.

A Patient-Controlled Intravenous Analgesia With Tramadol Ameliorates Postpartum Depression in High-Risk Woman After Cesarean Section: A Randomized Controlled Trial.

Background: Postpartum depression (PPD) is a severe psychiatric disorder. Its risk is associated with the cesarean section (CS). Currently, there are few early intervention strategies for these women with PPD who underwent CS. Methods: This was a parallel-group randomized controlled trial of singleton pregnant women who underwent elective CS in a tertiary referral hospital in China from October, 2017 to September, 2019. After operation, patients received randomly tramadol patient-controlled intravenous analgesia (PCIA; 4 mg/ml; TRA group), hydromorphone PCIA (0.04 mg/ml; HYD group), or ropivacaine patient-controlled epidural analgesia (PCEA; 1.5 mg/ml; ROP group) for 48 h in a 1:1:1 ratio. Total blinding during hospitalization was not feasible due to differences between the PCEA and PCIA treatments. All investigators who performed the follow-up were blinded to the group assignment. Outcomes: A total of 1,230 patients were enrolled for eligibility. Intention-to-treat analysis showed reduced incidence of PPD in the TRA group (n = 27 [6.6%]) than that in the HYD (10.2%, OR 1.62, 95% CI 0.98~2.68; p = 0.059) and ROP groups (10.5%, OR 1.66, 95% CI 1.01~2.75; p = 0.046) at 4 weeks post-operation, however, the difference was not statistically significant (Bonferroni corrected p = 0.118, p = 0.098, respectively). Subgroup analysis in high-risk women (preoperative Edinburgh Postpartum Depression Scale [EPDS] ≥10) showed a significantly lower incidence of PPD in the TRA group (16.5%) than in the HYD (32.6%) and ROP groups (30.9%) (Bonferroni corrected p = 0.022 and p = 0.038, respectively). The per-protocol analysis yielded similar results. Reported adverse events (AEs) were mostly mild. None of the women or infant discontinued treatment due to AEs. Conclusions: Tramadol PCIA after CS in high-risk women can help to reduce the risk of PPD at 4 weeks after elective CS. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT03309163?term=ETPPD&draw=2&rank=1; ClinicalTrials.gov (NCT03309163).

Design of Morphology-Controllable ZnO Nanorods/Nanopariticles Composite for Enhanced Performance of Dye-Sensitized Solar Cells.

A facile one-pot approach was developed for the synthesis of ZnO nanorods (NRs)/nanoparticles (NPs) architectures with controllable morphologies. The concrete state of existence of NPs and NRs could rationally be controlled through reaction temperature manipulation, i.e., reactions occured at 120, 140, 160, and 180 °C without stirring resulted in orderly aligned NRs, disordered but connected NRs/NPs, and relatively dispersed NRs/NPs with different sizes and lengths, respectively. The as-obained ZnO nanostructures were then applied to construct photoanodes of dye-sensitized solar cells, and the thicknesses of the resultant films were controlled for performance optimization. Under an optimized condition (i.e., with a film thickness of 14.7 µm), the device fabricated with the material synthesized at 160 °C exhibited the highest conversion efficiency of 4.30% with an elevated current density of 14.50 mA·cm-2 and an open circuit voltage of 0.567 V. The enhanced performance could be attributed to the coordination effects of the significantly enhanced dye absorption capability arising from the introduced NPs and the intrinsic fast electron transport property of NRs as confirmed by electrochemical impedance spectroscopy (EIS) and ultraviolet-visible (UV-vis) absorption.

Manganese-doped zinc oxide hollow balls for chemiresistive sensing of acetone vapors.

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.

Aliovalent Fe(iii)-doped NiO microspheres for enhanced butanol gas sensing properties.

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.

Design of SnO2 Aggregate/Nanosheet Composite Structures Based on Function-Matching Strategy for Enhanced Dye-Sensitized Solar Cell Performance.

Hierarchical SnO2 nanocrystallites aggregates (NAs) were prepared with a simple room temperature⁻based aqueous solution method followed by simple freeze-drying treatment. The as-prepared SnO2 NAs were subsequently combined with SnO2 nanosheet⁻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.

Coordination Polymer-Derived Multishelled Mixed Ni-Co Oxide Microspheres for Robust and Selective Detection of Xylene.

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.

Low Temperature Hydrothermal Synthesis of Visible-Light-Activated I-Doped TiO2 for Improved Dye Degradation.

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 and O2-, were evidenced to be involved in the degradation process and a possible mechanism was also proposed.