Hydrothermal Synthesis of SnO2 with Different Morphologies as Sensing Materials for HCHO Detection.

Morphology regulation is an effective strategy for improving the sensor sensitivity of transition metal oxide nanostructures. In this work, SnO2 with three different morphologies (nanorods, nanoparticles, and nanopillars) has been synthesized by a simple one-step solvothermal process with the addition of various solute ratios at 180 °C for 6 h for detecting formaldehyde (HCHO) at the optimum working temperature of 320 °C. Compared to nanorods and nanopillars, the created SnO2 nanoparticles exhibit a much faster response time and sensitivity than other samples, showing the fastest recovery time (18 s) with the highest sensitivity of 6-100 ppm of the HCHO gas. The sensing mechanism of the sensors is investigated by Brunauer-Emmett-Teller (BET) methods and X-ray photoelectron spectroscopy (XPS) analysis, revealing that the pore size distribution and amount of OV and OC improve the charge transfer and HCHO adsorption of nanoparticle sensors. Such an effect of morphology control on sensing performance paves an idea for the development of different structure-based HCHO sensors.

Constructing Single-Atom Active Sites Embedded in Hexagonal Boron Nitride for Adsorption and Sensing of Lithium Battery Thermal Runaway Gases.

The utilization and selectivity of single atoms have garnered significant attention among researchers. However, they are easy to agglomerate because of their high surface energy. To overcome this challenge, it is crucial to seek suitable carriers to anchor single metal atoms to achieve optimal performance. In this work, the structures of transition metal single atoms embedded in hexagonal boron nitride (MB2N2, M = Fe, Co, Ni, Cu, Zn) are constructed and used for the adsorption and sensing of lithium battery thermal runaway gases (H2, CO, CO2, CH4) through the DFT method. The adsorption behavior of MB2N2 was evaluated through the adsorption energy, sensitivity, and recovery time. The calculation results indicate that CoB2N2 exhibits strong adsorption capacity for both H2 and CO. The sensitivity of FeB2N2 toward CO is as high as 3.232 × 1016. Subsequently, the adsorption mechanism was studied through TDOS and PDOS, and the results showed that hybridization between orbitals enhanced the gas adsorption performance. This study presents novel approaches for designing single-atom carriers and developing MB2N2 sensors for detecting lithium battery thermal runaway gases.

Surface modification of Co3O4 nanosheets through Cd-doping for enhanced CO sensing performance.

The detection of hazardous CO gas is an important research content in the domain of the Internet of Things (IoT). Herein, we introduced a facile metal-organic frameworks (MOFs)-templated strategy to synthesize Cd-doped Co3O4 nanosheets (Cd-Co3O4 NSs) aimed at boosting the CO-sensing performance. The synthesized Cd-Co3O4 NSs feature a multihole nanomeshes structure and a large specific surface area (106.579 m2·g-1), which endows the sensing materials with favorable gas diffusion and interaction ability. Furthermore, compared with unadulterated Co3O4, the 2 mol % Cd-doped Co3O4 (2% Cd-Co3O4) sensor exhibits enhanced sensitivity (244%) to 100 ppm CO at 200 °C and a comparatively low experimental limit of detection (0.5 ppm/experimental value). The 2% Cd-Co3O4 NSs show good selectivity, reproducibility, and long-term stability. The improved CO sensitivity signal is probably owing to the stable nanomeshes construction, high surface area, and rich oxygen vacancies caused by cadmium doping. This study presents a facile avenue to promote the sensing performance of p-type metal oxide semiconductors by enhancing the surface activity of Co3O4 combined with morphology control and component regulation.

Adsorption of NO2, NO, NH3, and CO on Noble Metal (Rh, Pd, Ag, Ir, Pt, Au)-Modified Hexagonal Boron Nitride Monolayers: A First-Principles Study.

To investigate the application of modified hexagonal boron nitride (h-BN) in the detection and monitoring of harmful gases (NO2, NO, NH3, and CO), first-principles calculations are applied to study the geometric structure and electronic behavior of the adsorption system. In this paper, the four adsorption sites, namely, B, N, bridge, and hollow sites, are considered to explore the stable adsorption structure of metals (M = Rh, Pd, Ag, Ir, Pt, and Au) on the BN surface. The calculation results demonstrate that the geometric structures of metal at the N-site are relatively stable. Subsequently, the different adsorption structures of NO2, NO, NH3, and CO on M-BN are researched. The electron transfer, charge difference density, and work function of the stable adsorption structure are calculated. The results show that NO2, NO, and CO have the strongest adsorption capacity in the Ir-BN system, with adsorption energies of -2.705, -5.064, and -3.757 eV, respectively. The Pt-BN system has an excellent adsorption performance (-2.251 eV) for NH3. Compared with the M-BN system, the work function of the adsorption system increases after adsorbing NO2, while it decreases after adsorbing NH3. This work shows that h-BN with metal modification is a potential material for online monitoring of harmful gases.

WS2 supported PtOx clusters for efficient photocatalytic CO2 reduction: a DFT study.

Platinum (Pt) nanoparticles/nanoclusters are some of the most efficient cocatalysts for photocatalytic CO2 reduction. Nevertheless, the produced CO can lead to a poisoning effect due to the strong adsorption strength of the Pt cocatalysts. Using density functional theory, PtOx clusters with variable sizes (Pt4O6, Pt5O8, Pt7O10, and Pt8O13) are selected to load on WS2 (PtOx-WS2) for photocatalytic CO2 conversion. The calculated results demonstrate that PtOx-WS2 are highly stable, and the electron-rich PtOx clusters are beneficial for the photocatalytic CO2 reduction. All the PtOx-WS2 catalysts exhibit efficient photocatalytic performance for CO2 reduction. Especially, Pt4O6-, Pt5O8-, and Pt8O13-WS2 have acceptable or ultra-low ΔGmax (ΔG for the rate-determining step) of 0.57, 0.23, and 0.48 eV to produce CH3OH, HCOOH, and CH4, respectively. The photocatalytic activities of PtOx-WS2 are correlated with the adsorption strength of the key intermediates, and the strong interactions between PtOx-WS2 and *COOH or *HCOO can lower the free energy changes for the first hydrogenation step. More importantly, PtOx-WS2 can also weaken the adsorption strength of *CO and *HCOOH, which are conducive to forming *CHO. This work gives an in-depth insight to design novel catalysts and promote their catalytic activity for photocatalytic CO2 reduction.

Recent Progress in Spinel Ferrite (MFe2O4) Chemiresistive Based Gas Sensors.

Gas-sensing technology has gained significant attention in recent years due to the increasing concern for environmental safety and human health caused by reactive gases. In particular, spinel ferrite (MFe2O4), a metal oxide semiconductor with a spinel structure, has emerged as a promising material for gas-sensing applications. This review article aims to provide an overview of the latest developments in spinel-ferrite-based gas sensors. It begins by discussing the gas-sensing mechanism of spinel ferrite sensors, which involves the interaction between the target gas molecules and the surface of the sensor material. The unique properties of spinel ferrite, such as its high surface area, tunable bandgap, and excellent stability, contribute to its gas-sensing capabilities. The article then delves into recent advancements in gas sensors based on spinel ferrite, focusing on various aspects such as microstructures, element doping, and heterostructure materials. The microstructure of spinel ferrite can be tailored to enhance the gas-sensing performance by controlling factors such as the grain size, porosity, and surface area. Element doping, such as incorporating transition metal ions, can further enhance the gas-sensing properties by modifying the electronic structure and surface chemistry of the sensor material. Additionally, the integration of spinel ferrite with other semiconductors in heterostructure configurations has shown potential for improving the selectivity and overall sensing performance. Furthermore, the article suggests that the combination of spinel ferrite and semiconductors can enhance the selectivity, stability, and sensing performance of gas sensors at room or low temperatures. This is particularly important for practical applications where real-time and accurate gas detection is crucial. In conclusion, this review highlights the potential of spinel-ferrite-based gas sensors and provides insights into the latest advancements in this field. The combination of spinel ferrite with other materials and the optimization of sensor parameters offer opportunities for the development of highly efficient and reliable gas-sensing devices for early detection and warning systems.

Synthesis of Porous Hierarchical In2O3 Nanostructures with High Methane Sensing Property at Low Working Temperature.

Different hierarchical porous In2O3 nanostructures were synthesized by regulating the hydrothermal time and combining it with a self-pore-forming method. The gas-sensing test results show that the response of the sensor based on In2O3 obtained after hydrothermal reaction for 48 h is about 10.4 to 500 ppm methane. Meanwhile, it possesses good reproducibility, stability, selectivity and moisture resistance as well as a good exponential linear relationship between the response to methane and its concentration. In particular, the sensor based on In2O3 can detect a wide range of methane (10~2000 ppm) at near-room temperature (30 °C). The excellent methane sensitivity of the In2O3 sensor is mainly due to its unique nanostructure, which has the advantages of both porous and hierarchical structures. Combined with the DFT calculation, it is considered that the sensitive mechanism is mainly controlled by the surface adsorbed oxygen model. This work provides a feasible strategy for enhancing the gas sensitivity of In2O3 toward methane at low temperatures.

Improved TEA Sensitivity and Selectivity of In2O3 Porous Nanospheres by Modification with Ag Nanoparticles.

A highly sensitive and selective detection of volatile organic compounds (VOCs) by using gas sensors based on metal oxide semiconductor (MOS) has attracted increasing interest, but still remains a challenge in gas sensitivity and selectivity. In order to improve the sensitivity and selectivity of In2O3 to triethylamine (TEA), herein, a silver (Ag)-modification strategy is proposed. Ag nanoparticles with a size around 25-30 nm were modified on pre-synthesized In2O3 PNSs via a simple room-temperature chemical reduction method by using NaBH4 as a reductant. The results of gas sensing tests indicate that after functionalization with Ag, the gas sensing performance of In2O3 PNSs for VOCs, especially for TEA, was remarkably improved. At a lower optimal working temperature (OWT) of 300 °C (bare In2O3 sensor: 320 °C), the best Ag/In2O3-2 sensor (Ag/In2O3 PNSs with an optimized Ag content of 2.90 wt%) shows a sensitivity of 116.86/ppm to 1-50 ppm TEA, about 170 times higher than that of bare In2O3 sensor (0.69/ppm). Significantly, the Ag/In2O3-2 sensor can provide a response (Ra/Rg) as high as 5697 to 50 ppm TEA, which is superior to most previous TEA sensors. Besides lower OWT and higher sensitivity, the Ag/In2O3-2 sensor also shows a remarkably improved selectivity to TEA, whose selectivity coefficient (STEA/Sethanol) is as high as 5.30, about 3.3 times higher than that of bare In2O3 (1.59). The sensitization mechanism of Ag on In2O3 is discussed in detail.

Noninvasive ventilation with a helmet in patients with acute respiratory failure caused by chest trauma: a randomized controlled trial.

Noninvasive ventilation (NIV) is beneficial in acute respiratory failure (ARF) caused by chest trauma; however, NIV-related complications affect the efficacy. We evaluated whether NIV with helmet decreases the incidence of complications and improves its effects in a single center. Patients with ARF after chest trauma were randomized to receive NIV with helmet or face mask. The primary outcome was the rate of NIV-related complications. Secondary outcomes were PaO2/FiO2, patient's tolerance, intubation rate, length of intensive care unit (ICU) stay, and ICU mortality. The trial was terminated early after an interim analysis with 59 patients. The incidence of complications was lower in the helmet group [10% (3/29) vs 43% (13/30), P = 0.004], and PaO2/FiO2s were higher at 1 h and at the end of NIV (253.14 ± 64.74 mmHg vs 216.06 ± 43.86 mmHg, 277.07 ± 84.89 mmHg vs 225.81 ± 63.64 mmHg, P = 0.013 and 0.012) compared with them in face mask group. More patients reported excellent tolerance of the helmet vs face mask after 4 h of NIV [83% (24/29) vs 47% (14/30), P = 0.004] and at the end of NIV [69% (20/29) vs 30% (9/30), P = 0.03]. Differences in intubation rate, ICU stay, and mortality were non-significant (P = 0.612, 0.100, 1.000, respectively). NIV with helmet decreased NIV-related complications, increased PaO2/FiO2, and improved tolerance compared with NIV with face mask in patients with chest trauma.Trial registration: Registered in the Chinese Clinical Trial Registry (ChiCTR1900025915), a WHO International Clinical Trials Registry Platform ( http://www.chictr.org.cn/searchprojen.aspx ).

Facile and Efficient Fabrication of Bandgap Tunable Carbon Quantum Dots Derived From Anthracite and Their Photoluminescence Properties.

Low-cost and earth-abundant coal has been considered to have a unique structural superiority as carbon sources of carbon quantum dots (CQDs). However, it is still difficult to obtain CQDs from raw coal due to its compactibility and lower reactivity, and the majority of the current coal-based CQDs usually emit green or blue fluorescence. Herein, a facile two-step oxidation approach (K2FeO4 pre-oxidation and H2O2 oxidation) was proposed to fabricate bandgap tunable CQDs from anthracite. The K2FeO4 pre-oxidation can not only weaken the non-bonding forces among coal molecules which cause the expansion of coal particles, but also form a large number of active sites on the surface of coal particles. The above effects make the bandgap tunable CQDs (blue, green, or yellow fluorescence) can be quickly obtained from anthracite within 1 h in the following H2O2 oxidation by simply adjusting the concentration of H2O2. All the as-prepared CQDs contain more than 30 at% oxygen, and the average diameters of which are <10 nm. The results also indicate that the high oxygen content only can create new energy states inside the band gap of CQDs with average diameter more than 3.2 ± 0.9 nm, which make the as-prepared CQDs emit green or yellow fluorescence.

Rapid detection of low concentration CO using Pt-loaded ZnO nanosheets.

Unloaded and Pt-loaded ZnO nanosheets with 120-170 nm sizes were successfully synthesized by a facile one-pot hydrothermal route followed by a calcination treatment. The as-synthesized samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It can be clearly observed that Pt nanoparticles with the diameter of 3-5 nm were uniformly loaded on the surface of ZnO nanosheets. A contrastive study based on CO gas sensing performance of bare ZnO and Pt/ZnO was carried out. According to the measurement results, the loading of Pt remarkably upgraded the sensing capability toward CO. The 0.50 at.% Pt/ZnO based gas sensor exhibited an obvious response value of 3.57 toward 50 ppm CO and fast response/recovery time (6/19 s). Besides, the detection limit was as low as 0.10 ppm and the optimal operating temperature was decreased from 210 °C to 180 °C. The enhanced CO sensing performance by Pt nanoparticles could be attributed to the combination of chemical sensitization and electronic sensitization. The 0.50 at.% Pt/ZnO is an efficient sensor material for rapidly detecting low-concentration CO.

A luminescent terbium coordination complex as multifunctional sensing platform.

In this paper, we report the synthesis of a multifunctional fluorescent probe Tb-CP, Tb(HL)(EtOH)2(NO3)2 (HPU-10) (H2L = 2,6-bis-(5-pyridin-4-yl-1H-[1,2,4]triazol-3-yl)- pyridine), and demonstrate that this novel chemosensor has the property of ratiometric detection of Zn2+ and Cd2+. The detection limit of HPU-10 sensing Zn2+ and Cd2+ is 0.319 and 0.965 µM, respectively. The sensing mechanism can be explained by (i) the decomposition of HPU-10 and (ii) the recombination of Zn2+ or Cd2+ with ligand forming 2HL--Zn2+ or 2HL--Cd2+, respectively. Moreover, the fluorescent sensor HPU-10 can detect the nitroaromatic compound 2, 4-DNP via a fluorescence quenching mechanism. The detection limits obtained from linear regression curve plots of 2, 4-DNP is calculated to be 1.69 µM. In addition, the possible use of the probe coated paper for tracing the target analytes has also been presented.

Graphitic Carbon Nitride Nanosheets Decorated Flower-like NiO Composites for High-Performance Triethylamine Detection.

The graphitic carbon nitride (g-C3N4) nanosheets decorated three-dimensional hierarchical flower-like nickel oxide (NiO) composites (NiO/g-C3N4, Ni/CN) were synthesized via a facile hydrothermal method combined with a subsequent annealing process. The structure and morphology of the as-prepared Ni/CN composites were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen absorption. The gas-sensing experiments reveal that the composites with 10 wt % two-dimensional g-C3N4 (Ni/CN-10) not only exhibits the highest response of 20.03 that is almost 3 times higher than pristine NiO to 500 ppm triethylamine (TEA) at the optimal operating temperature of 280 °C but also shows a good selectivity toward TEA. The gas-sensitivity promotion mechanism is attributed to the internal charge transfer within the p-n heterojunction. Furthermore, the high specific surface area of the Ni/CN composites promotes adequate contact and reaction between the composites and triethylamine molecules. Therefore, the Ni/CN sensor has a great potential application in detecting TEA.

Improving methane gas sensing performance of flower-like SnO2 decorated by WO3 nanoplates.

The three-dimensional (3D) hierarchical WO3-SnO2 nanoflowers (NFs) composites were successfully synthesized via a simple impregnation method by using WO3 and SnO2 prepared by hydrothermal method as precursors. The structure and morphology of the as-prepared samples were investigated by the techniques of X-ray diffraction (XRD), field-emission electron scanning microscopy (FESEM), transmission electron microscopy (TEM) and N2 sorption. These results indicated that SnO2 and WO3-SnO2 nanostructures with a diameter of about 500 nm self-assembled by numerous nanorods of about 200 nm in length. Gas sensing test results show that the nanostructure WO3-SnO2 nanocomposites possess better methane sensing properties than that of pure SnO2. The modification of WO3 nanoplates reduces the optimum working temperature of SnO2 based sensor from 120 °C to 110 °C, the response of WO3-SnO2 based sensor to 500 ppm methane at 110 °C is 2.3 times of that of pure SnO2 based sensor. In addition, the WO3-SnO2 based sensor possesses lower detection limit, good repeatability and stability. The improved gas-sensing mechanism of the nanocomposite based sensors for methane detection is also discussed in detail.

Enhanced Methane Sensing Properties of WO3 Nanosheets with Dominant Exposed (200) Facet via Loading of SnO2 Nanoparticles.

Methane detection is extremely difficult, especially at low temperatures, due to its high chemical stability. Here, WO3 nanosheets loaded with SnO2 nanoparticles with a particle size of about 2 nm were prepared by simple impregnation and subsequent calcination using SnO2 and WO3·H2O as precursors. The response of SnO2-loaded WO3 nanosheet composites to methane is about 1.4 times higher than that of pure WO3 at the low optimum operating temperature (90 °C). Satisfying repeatability and long-term stability are ensured. The dominant exposed (200) crystal plane of WO3 nanosheets has a good balance between easy oxygen chemisorption and high reactivity at the dangling bonds of W atoms, beneficial for gas-sensing properties. Moreover, the formation of a n⁻n type heterojunction at the SnO2-WO3 interface and additionally the increase of specific surface area and defect density via SnO2 loading enhance the response further. Therefore, the SnO2-WO3 composite is promising for the development of sensor devices to methane.

[Status of diagnosis and management of acute appendicitis in 2017: a national multi-center retrospective study].

OBJECTIVE: To analyze the current status of diagnosis and management of acute appendicitis (AA) in China. METHODS: Questionnaire survey was used to retrospectively collect data of hospitalized patients with AA from 43 medical centers nationwide in 2017 (Sort by number of cases provided: Jinling Hospital of Medical School of Nanjing University, The First Affiliated Hospital of Xinjiang Medical University, Lu'an People's Hospital, Tengzhou Central People's Hospital, Dalian Central Hospital, The Affiliated Hospital of Xuzhou Medical University, Dongying People's Hospital, Jinjiang Hospital of Traditional Chinese Medicine, Huangshan Shoukang Hospital, Xuyi People's Hospital, Nanjing Jiangbei People's Hospital, Lanzhou 940th Hospital of PLA, Heze Municipal Hospital, The First College of Clinical Medical Science of China Three Gorges University, Affiliated Jiujiang Hospital of Nanchang University, The Second People's Hospital of Hefei, Affiliated Central Hospital of Shandong Zaozhuang Mining Group, The Third People's Hospital of Kunshan City, Xuzhou First People's Hospital, The 81st Group Army Hospital of PLA, Linyi Central Hospital, The General Hospital of Huainan Eastern Hospital Group, The 908th Hospital of PLA, Liyang People's Hospital, The 901th Hospital of Joint Logistic Support Force, The Third Affiliated Hospital of Chongqing Medical University, The Fourth Hospital of Jilin University, Harbin Acheng District People's Hospital, The First Affiliated Hospital of Zhengzhou University, Nanjing Luhe People's Hospital, Taixing Municipal People's Hospital, Baotou Central Hospital, The Affiliated Hospital of Nantong University, Linyi People's Hospital, The 72st Group Army Hospital of PLA, Zaozhuang Municipal Hospital, People's Hospital of Dayu County, Taixing City Hospital of Traditional Chinese Medicine, Suzhou Municipal Hospital, Beijing Guang'anmen Hospital, Langxi County Hospital of Traditional Chinese Medicine, Nanyang Central Hospital, The Affiliated People's Hospital of Inner Mongolia Medical University).The diagnosis and management of AA were analyzed through unified summary. Different centers collected and summarized their data in 2017 and sent back the questionnaires for summary. RESULTS: A total of 8 766 AA patients were enrolled from 43 medical centers, including 4 711 males (53.7%) with median age of 39 years and 958 (10.9%) patients over 65 years old. Of 8 776 patients, 5 677 cases (64.6%) received one or more imaging examinations, and the other 3 099 (35.4%) did not receive any imaging examination. A total of 1 858 (21.2%) cases received medical treatment, mainly a combination of nitroimidazoles (1 107 cases, 59.8%) doublet regimen, followed by a single-agent regimen of non-nitroimidazoles (451 cases, 24.4%), a nitroimidazole-free doublet regimen (134 cases, 7.2%), a triple regimen of combined nitroimidazoles (116 cases, 6.3%), nitroimidazole alone (39 cases, 2.1%) and nitroimidazole-free triple regimen (3 cases, 0.2%). Of the 6 908 patients (78.8%) who underwent surgery, 4 319 (62.5%) underwent laparoscopic appendectomy and 2589 (37.5%) underwent open surgery. Ratio of laparotomy was higher in those patients under 16 years old (392 cases) or over 65 years old (258 cases) [15.1%(392/2 589) and 10.0%(258/2 589), respectively, compared with 8.5%(367/4 316) and 8.0%(347/4 316) in the same age group for laparoscopic surgery, χ²=91.415, P<0.001; χ²=15.915,P<0.001]. Patients with complicated appendicitis had higher ratio of undergoing open surgery as compared to those undergoing laparoscopic surgery [26.7%(692/2 589) vs. 15.6%(672/4 316), χ²=125.726, P<0.001].The cure rates of laparoscopic and open surgery were 100.0% and 99.8%(2 585/2 589) respectively without significant difference (P=0.206). Postoperative complication rates were 4.5%(121/2 589) and 4.7%(196/4 316) respectively, and the difference was not statistically significant (χ²=0.065, P=0.799). The incidence of surgical site infection was lower (0.6% vs. 1.7%, χ²=17.315, P<0.001), and hospital stay was shorter [6(4-7) days vs. 6(5-8) days, U=4 384 348.0, P<0.001] in the laparoscopic surgery group, while hospitalization cost was higher (median 12 527 yuan vs. 9 342 yuan, U=2 586 809.0, P<0.001). CONCLUSIONS: The diagnosis of acute appendicitis is still clinically based, supplemented by imaging examination. Appendectomy is still the most effective treatment at present. Laparoscopic appendectomy has become the main treatment strategy, but anti-infective drugs are also very effective.

Highly stable hole-conductor-free perovskite solar cells based upon ammonium chloride and a carbon electrode.

Organic-inorganic hybrid perovskite solar cells (PSCs) have become a research hotspot due to the impressive photovoltaic performance. The perovskite film plays an extremely important role in the light-to-electricity conversion, meanwhile, the stability of PSCs is also an important factor affecting the application of devices. Here we demonstrate a kind of stable PSCs by using simple solution-process in an air enviroment with about 45% relative humidity. Firstly, the NH4Cl was added to the perovskite precursor solution to adjust the kinetics of crystallization and growth of active layer, and then obtain high-quality CH3NH3PbI3 perovskite films. Hydrophobic carbon electrode was used to protect the perovskite active layers and further improve the stability of PSCs, which optimized the structure of the devices at the same time. We adjusted the amount of NH4Cl in the perovskite precursor solution (PbI2: CH3NH3I: NH4Cl = 1: 1: x (x = 0 ∼ 1), and investigated the effect of that on the properties of perovskite active layers and PSCs. The above results showed that the devices achieved fully covered perovskite thin films and improved the photovoltaic performance of PSCs when the NH4Cl additive was x  = 0.8. The short-circuit current density (Jsc), fill factor (FF) and power conversion efficiency (PCE) were significantly enhenced. Under the condition of ambient air and no encapsulation, the PSCs exhibited good stability after 576 h test, and the PCE was still about 96% of the initial efficiency.

A lanthanide-based magnetic nanosensor as an erasable and visible platform for multi-color point-of-care detection of multiple targets and the potential application by smartphone.

The sensitive, selective and point-of-care detection of dipicolinic acid (DPA) is of great significance for the prevention of the anthrax virus and the containment of bioterrorism. In this work, a multi-color fluorescent nanoprobe composed of lanthanides and magnetic nanoparticles (Fe3O4@CePO4:Tb-EDTA-Eu) has been designed, in which the portion of Fe3O4@CePO4:Tb can be used as the internal stable signal of green fluorescence, while the EDTA-Eu part can be used as the sensitive reaction signal for monitoring DPA. Upon the addition of DPA, the red fluorescence of Eu3+ ions is significantly enhanced, while the fluorescent color of the nanoprobes can change from green to red (such as yellow-green, orange-yellow and orange-red), achieving visual multi-color fluorescent detection even by the naked eye. By using the magnetic separation method, the composites can be easily purified for point-of-care testing. More importantly, the nanoprobe fixed test pieces enable real-time analysis of DPA by using an easy-to-access color-scanning application on a smartphone. Furthermore, the fluorescence intensity can be quenched by the addition of Cu2+, which leads to a rewritable nanosensor and can be used in the detection of cysteine (Cys) with high sensitivity. With the addition of Cys, this erasable nano detection platform can also display the original multi-color visual point-of-care detection. With further optimization, this new type of multi-color fluorescent assay is promising in point-of-care clinics for multi-target diagnostics.

Oxygen Reduction Activity and Stability of Composite Pdx/Co-Nanofilms/C Electrocatalysts in Acid and Alkaline Media.

The morphology tuning of Pd and Pd-M nanoparticles is one of the significant strategies to control the catalytic activity toward oxygen reduction reaction (ORR). In this study, composite Pdx/Co-nanofilms/C electrocatalysts of Pd nanoparticles implanted onto Co nanofilms were synthesized on an immiscible ionic liquid (IL)/water interface for ORR. The Pd nanoparticles implanted onto Co nanofilms show a marked distortion of crystal lattice and surface roughness. These Pdx/Co-nanofilms/C electrocatalysts exhibit enhanced activity for ORR compared with Pd/C and PdxCo/C catalysts in both acid and alkaline solutions, in which the Pd3/Co-nanofilms/C catalyst displays the highest ORR mass activity. The superior ORR mass activities of the fabricated Pdx/Co-nanofilms/C catalysts may be mainly attributed to their larger catalytic areas, which are conferred by the rough surface of Pd nanoparticles with a distorted crystal lattice, and the synergistic effect between the surface Pd atoms and the 2D Co nanofilm substrate. The relationship between ORR mass activity and Pd/Co atom ratio varies in different electrolytes. Furthermore, by using proper heat-treatment methods, the Pdx/Co-nanofilms/C catalysts exhibit improved cycling stability compared with pure Pd/C catalyst after extended potential cycling.

Hydrothermal Synthesis of CeO2-SnO2 Nanoflowers for Improving Triethylamine Gas Sensing Property.

Developing the triethylamine sensor with excellent sensitivity and selectivity is important for detecting the triethylamine concentration change in the environment. In this work, flower-like CeO2-SnO2 composites with different contents of CeO2 were successfully synthesized by the one-step hydrothermal reaction. Some characterization methods were used to research the morphology and structure of the samples. Gas-sensing performance of the CeO2-SnO2 gas sensor was also studied and the results show that the flower-like CeO2-SnO2 composite showed an enhanced gas-sensing property to triethylamine compared to that of pure SnO2. The response value of the 5 wt.% CeO2 content composite based sensor to 200 ppm triethylamine under the optimum working temperature (310 °C) is approximately 3.8 times higher than pure SnO2. In addition, CeO2-SnO2 composite is also significantly more selective for triethylamine than pure SnO2 and has better linearity over a wide range of triethylamine concentrations. The improved gas-sensing mechanism of the composites toward triethylamine was also carefully discussed.