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Phosgene, one of the common chemicals in many industry areas, is extremely harmful to human and the environment. Thus, it is necessary to design the advanced materials to detect or remove phosgene effectively. In fact, detection or adsorption of some small gas molecules are not the most difficult to actualize. Whereas, one of the primary challenges is the gas molecules desorption from the adsorbent for the purpose of recycling of substrate materials since the small gas molecules interacts strongly with the substrates. In this work, the interaction between the phosgene molecule and pristine or Mn-doped graphene sheets with different electric field and charge state are investigated by using first-principles simulations. Our results show that the adsorption energy of phosgene on Mn-doped graphene is dramatically weakened by applying an external negative electric field but is obviously enhanced by introducing a positive electric field. These processes can be easily controlled by transform the direction of the electric field. Thus, introducing an external electric field or charge in the system may be an excellent method to control the phosgene molecule adsorption and desorption on Mn-doped graphene sheet. All energy needed is just a small quantity of electricity, which satisfies well the requirement of green chemistry and sustainable development. The mechanism and reason of reversible adsorption/desorption is also revealed in terms of energy, charge distribution and orbital analysis. Such spontaneous adsorption or desorption makes Mn-doped graphene to be used as an excellent reusable scavenger of phosgene. [ABSTRACT FROM AUTHOR]

Development of high performance room temperature sensors remains a grand challenge for high demand of practical application. Metal oxide semiconductors (MOSs) have many advantages over others due to their easy functionalization, high surface area, and low cost. However, they typically need a high work temperature during sensing process. Here, p-type sensing layer is reported, consisting of pore-rich dumbbell-like Co 3 O 4 particles (DP-Co 3 O 4 ) with intrinsic high catalytic activity. The gas sensor (GS) based DP-Co 3 O 4 catalyst exhibits ultrahigh NH 3 sensing activity along with excellent stability over other structure based NH 3 GSs in room temperature work environment. In addition, the unique structure of DP-Co 3 O 4 with pore-rich and high catalytic activity endows fast gas diffusion rate and high sensitivity at room temperature. Taken together, the findings in this work highlight the merit of integrating highly active materials in p-type materials, offering a framework to develop high-sensitivity room temperature sensing platforms. [ABSTRACT FROM AUTHOR]

The adsorption of the phosgene molecule on pristine graphene and transition metal doped (TM = Zr, Mo, Ti, Mn, Fe, Co) graphene is investigated using the first principles method based on density functional theory. The nature of interaction between the phosgene molecule and pristine graphene or transition metal doped graphene (TM-doped graphene) is discovered by geometries, adsorption energies, Mulliken charge distribution, density of states analysis and UV spectrum. Computational results show that the interaction between the phosgene molecule and pristine graphene is a weak physisorption. But doping with transition metals results in stronger chemical adsorption. This is due to the formation of a chemical bond between the metal atom and oxygen atom of phosgene, which makes TM-doped graphene really promising material for phosgene removal. TM-doped graphene also exhibits different electronic properties after adsorbing phosgene, compared with pristine graphene. Furthermore, the calculations reveal that UV spectrum of the TM-doped graphene is modified by the phosgene adsorption. Thus, the significant variations in electronic and optical properties of the TM-doped graphene sheet as interacting with the phosgene can be utilized to detect the phosgene. [ABSTRACT FROM AUTHOR]

Aiming to enhance the stability of noble metal nanoparticles that are anchored on the surface of colloidal carbon spheres (CCSs), we designed and prepared a new kind of sandwich-structured ZIF-8@Pd-CCS microsphere. Typically, uniform CCSs were first synthesized by the aromatization and carbonization of glucose under hydrothermal conditions. Subsequently, noble metal nanoparticles, herein Pd nanoparticles, were attached to the surface of CCSs via self-reduction route, followed by in situ assembly of a thin layer of ZIF-8 over the Pd nanoparticles to form the sandwich-type ZIF-8@Pd-CCS microspheres. X-ray diffraction (XRD) patterns and Fourier transform infrared spectroscopy (FTIR) spectra confirmed the presence of crystalline ZIF-8, while TEM analysis revealed that the ZIF-8 shells were closely bound to the Pd-loaded CCSs. The shell thickness could be tuned by varying the ZIF-8 assembly cycles. Further, liquid-phase hydrogenation of 1-hexene as the probe reaction was carried out over the ZIF-8@Pd-CCS microspheres and results showed that the prepared microspheres exhibited excellent agglomeration-resistant and leach-proof properties for the Pd nanoparticles, thus leading to the good reusability of the ZIF-8@Pd-CCS microspheres. [ABSTRACT FROM AUTHOR]

A new class of single/several-layer conductive Langmuir-Blodgett MOF films were prepared for ultralow concentration H 2 O 2 detection, creating a new record of H 2 O 2 detection limit based on non-precious catalysts (10−10, m/m). • A simple and scalable method to prepare conductive metal-organic LB films. • A new record of H 2 O 2 detection limit based on the non-precious LB films (10−10, m/m). • Quick response, good sensitivity, high stability, and perfect reproducibility. • Reaction mechanism and electron transfer processes at the internal interfaces. The detection of low-concentration hydrogen peroxide (H 2 O 2) has important theoretical-significance and practical value in many fields, such as medical science, biological chemistry, and food safety inspection. Traditional commercial H 2 O 2 test paper and detection technology can only reach the detection limit of 10−3–10−5 (mass fraction). In this paper, we report a simple method to prepare 2D MOF (metal-organic frameworks) [Co 3 (HOB) 2 ] n films based on Langmuir-Blodgett (LB) method combined with layer-by-layer growth technique. Even 3-layer [Co 3 (HOB) 2 ] n films can realize the lowest H 2 O 2 detection limit of 1.05 × 10−8 wt% (3.08 nmol·L−1) based on the resultant 2D MOF catalyst. Meanwhile, density functional theory (DFT) calculations revealed that Co2+ ions of the LB films decreased the energy of [HOOH] transforming into [HO 2 ] during the H 2 O 2 reduction reactions, thus speeding up the decomposition of H 2 O 2. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the pH sensitivity enhancement of AlGaN/GaN ion-sensitive field-effect transistor (ISFET) coated by Al 2 O 3 film on the sensing area utilizing atomic layer deposition (ALD). The presence of the Al 2 O 3 film leads to an obvious reduction of surface state density as well as leakage current in the solution, which is beneficial for improving the stability of the ISFET. Furthermore, the sensitivity of the ISFET was improved to 57.8 mV/pH, which is very close to the Nernstian limit at room temperature. The pH sensitivity enhancement can be explained by the higher density of sensing site as well as better surface hydrophilicity. [ABSTRACT FROM AUTHOR]

In this work, core-shell WO 3 -SnO 2 (CS-WS) nanofibers (NFs) have been successfully synthesized via a coaxial electrospinning approach. The structure and morphology characteristics of the resultant products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS). To investigate the sensing mechanism of the CS-WS NFs, sensors based on SnO 2 NFs, WO 3 NFs, and SnO 2 -WO 3 composite NFs were fabricated respectively, and their gas sensing properties were investigated by using CO, ethanol, toluene, acetone, and ammonia as the test gas. The results indicated that the CS-WS NFs exhibited a good response to ethanol (5.09 at 10 ppm) and short response/recovery time (18.5 s and 282 s) compared with the other test gases. The enhanced ethanol sensing properties of CS-WS NFs compared with those of SnO 2 NFs were closely associated with the CS structure and its derivative effect due to the different work function of SnO 2 and WO 3 . The approach proposed in this study may contribute to the realization of more sensitive metal oxide semiconductor (MOS) core-shell heterostructure sensors. [ABSTRACT FROM AUTHOR]

The increasing growth of the inkjet market makes the inkjet printing more necessary. A composite material based on core-shell structure has been developed and applied to prepare inkjet printing layer. In this contribution, the ink printing record layers based on SiO 2 @Al 13 core-shell composite was elaborated. The prepared core-shell composite materials were characterized by X-ray photoelectron spectroscopy (XPS), zeta potential, X-ray diffraction (XRD), scanning electron microscopy (SEM). The results proved the presence of electrostatic adsorption between SiO 2 molecules and Al 13 molecules with the formation of the well-dispersed system. In addition, based on the adsorption and the liquid permeability analysis, SiO 2 @Al 13 ink printing record layer achieved a relatively high ink uptake (2.5 gmm −1 ) and permeability (87%), respectively. The smoothness and glossiness of SiO 2 @Al 13 record layers were higher than SiO 2 record layers. The core-shell structure facilitated the dispersion of the silica, thereby improved its ink absorption performance and made the clear printed image. Thus, the proposed procedure based on SiO 2 @Al 13 core-shell structure of dye particles could be applied as a promising strategy for inkjet printing. [ABSTRACT FROM AUTHOR]

Cobalt Prussian blue analogue Co 3 [Co(CN) 6 ] 2 is used as a precursor material to obtain bamboo-shaped nitrogen-doped carbon nanotubes (Co@NCNTs-2), with low cobalt metal content through solid-state thermal conversion and acid pickling process. Then the active material S is combined with the host materials (Co@NCNTs-2) via a traditional melt-infusion method, the obtained cathode material shows better battery capacity and cycle stability in lithium-sulfur batteries. [Display omitted] • N-doped carbon nanotubes with low Co metal content are obtained. • Co is encapsulated in the interior and N is distributed on the outside of Co@NCNTs-2. • Co@NCNTs-2 provide active sites to improve the redox reaction of sulfur cathode. • Co@NCNTs-2 shows its superiority as a cathode material host for Li-S batteries. Functional and active carbon material is of great concern in facilitating the performance of lithium-sulfur (Li-S) battery. In this work, we develop a bamboo-like nitrogen-doped carbon nanotubes (Co@NCNTs-2) with low cobalt metal content, which acts as not only the host matrix for sulfur loading but also an efficient catalyst for the adsorption and conversion of lithium polysulfides (LiPSs). The characterization results show that the Co particles are mainly encapsulated inside the Co@NCNTs-2, and the N species are mainly distributed on the outer surface of Co@NCNTs-2. The Co particles are the growth sites of carbon nanotubes and are wrapped by carbon to form Co@NCNTs-2. It is confirmed that the uniform graphitized structure contributes to charge transfer, while the enriched N species assist the trap and catalytic conversion of the polysulfides, thus helping to restrain the shuttle effect. As a result, the resultant Co@NCNTs-2-S cathode presents high reversible capacity at different current densities and exhibits superior cycling stability for 300 cycles at 0.5 C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Formation of steam generator fouling was investigated by experiment and simulation. • A double layer structure was firstly found in the large deposited fouling particles. • Distribution of fouling particles could be influenced by oxide layer. • The nature of the oxide was verified to be modified by fouling deposition. The fouling in the steam generator (SG), seriously affecting the internal integrity of SG tube, heat transfer efficiency and control of water chemistry, is commonly caused by the growth of thick oxides and deposition of soluble particles in the secondary circuit of pressure water reactor (PWR) nuclear power plant (NPP). Herein we describe the nucleation, aggregation and growth mechanism of fouling containing different metallic cations. Three fouling layers were observed at the crevice position of SG tube and the large Fe 3 O 4 fouling particles exhibited a double layer structure. The growth process and direction of fouling particles were found to be related with the oxide layer. Meanwhile, the deposition process of fouling is affected by the matrix shape and distribution of the massive fouling particles, and large fouling particle grows preferentially in the direction of primary crystal plane on the surface of the oxide layer. The nucleation, agglomeration, adsorption, growth of the oxide was identified to be affected significantly by fouling deposition, however, it exhibited possibly opposing impacts on the reliability of SG tubes. [ABSTRACT FROM AUTHOR]

Abstract: The highly ordered TiO2 thin films are prepared by anodic oxidation and calcined at 300, 400, 500 and 600°C, respectively. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) are employed to analyze the structure and the morphology of the TiO2 films. We design a novel sensor to investigate the humidity sensing behaviours of the samples. The samples calcined at 600°C show high sensitivity with nearly two orders change in the resistance and short response and recovery time (<190s) during the relative humidity variation from 11 to 95%. [Copyright &y& Elsevier]

In this manuscript, we report a one-step microwave-hydrothermal preparation of NiS/rGO hybrid electrode material. Compared to the conventional multi-step preparation process, the new method is green without using any chemical surfactant and the preparation time is significantly reduced from several days to only 6 h. The as-prepared NiS/rGO hybrid exhibits a low resistance of ~0.48 Ω, ultrahigh specific capacitance of 1745.67 F g−1 at 1 A g−1 and a high capacity retention of 451.21 F g−1 at 10 A g−1 after 3000 consecutive cycles with high reproducibility. The assembled symmetric solid-state supercapacitor (SCC) based on NiS/rGO hybrid electrode material shows a specific capacitance of 14.20 F g−1, a high energy density of 7.1 Wh kg−1 and a high power density of 1836 W kg−1, demonstrating a great potential for the application in the field of energy storage devices. • A novel and high-efficiency one-step microwave-hydrothermal method was developed to prepare NiS/rGO hybrid electrode material. • The as-prepared NiS/rGO hybrid electrode exhibits an ultrahigh specific capacitance of 1745.67 F g−1 at 1 A g−1. • The assembled symmetric solid-state supercapacitor based on NiS/rGO hybrid electrode exhibits both a high energy density of 7.1 Wh kg−1 and a high power density of 1836 W kg−1. • The rGO film has played an important role for improving the aggregation and conductivity of NiS nanoparticles in NiS/rGO hybrid. The NiS/reduced graphene (rGO) hybrid has recently attracted increasing interest due to its synthetic effect to improve the conductivity and volume expansion of NiS during charge-discharge cycles as well as the capacitive performance of graphene. However, the preparation of high-performance NiS/rGO hybrid electrode material is still a challenging issue due to its complex multi-step preparation process, which causes low reproducibility, long-time and large-energy consuming. Herein, we report a one-step microwave-hydrothermal preparation of NiS/rGO hybrid electrode material. Compared to the conventional multi-step preparation process, the new method is green without using any chemical surfactant and the preparation time is significantly reduced from several days to only 6 h. The as-prepared NiS/rGO hybrid exhibits a low resistance of ~0.48 Ω, ultrahigh specific capacitance of 1745.67 F g−1 at 1 A g−1 and a high capacity retention of 451.21 F g−1 at 10 A g−1 after 3000 consecutive cycles with high reproducibility. The assembled symmetric solid-state supercapacitor (SCC) based on NiS/rGO hybrid electrode material shows a specific capacitance of 14.20 F g−1, a high energy density of 7.1 Wh kg−1 and a high power density of 1836 W kg−1, demonstrating a great potential for the application in the field of energy storage devices. [ABSTRACT FROM AUTHOR]