We fabricated dye-sensitized MoS2 photodetectors that utilized a single-layer MoS2 treated with rhodamine 6G (R6G) organic dye molecules (with an optical band gap of 2.38 eV or 521 nm). The proposed photodetector showed an enhanced performance with a broad spectral photoresponse and a high photoresponsivity compared with the properties of the pristine MoS2 photodetectors. The R6G dye molecules deposited onto the MoS2 layer increased the photocurrent by an order of magnitude due to charge transfer of the photoexcited electrons from the R6G molecules to the MoS2 layer. Importantly, the photodetection response extended to the infrared (λ < 980 nm, which corresponded to about half the energy band gap of MoS2), thereby distinguishing the device performance from that of a pristine MoS2 device, in which detection was only possible at wavelengths shorter than the band gap of MoS2, i.e., λ < 681 nm. The resulting device exhibited a maximum photoresponsivity of 1.17 AW(–1), a photodetectivity of 1.5 × 10(7) Jones, and a total effective quantum efficiency (EQE) of 280% at 520 nm. The device design described here presents a significant step toward high-performance 2D nanomaterial-based photodetector.

Chiral materials composed of organized nanoparticle superstructures have promising applications to photonics and sensing. Reliable customization of the chiroptical properties of these materials remains an important goal; hence, we report a customizable scheme making use of modular gelator components for controlling the helicity and formation of nanofibers over long length scales resulting in hydrogel templates. Controlled growth of gold nanoparticles at spatially arranged locations along the nanofiber is achieved by UV reduction of Au(I) ions on the supramolecular templates. The resulting materials were found to have significant interparticle interactions and well-defined helicity to provide high quality, chiroptically active materials. With this novel approach, the tailored assembly of nanoparticle superstructures with predictable chiroptical properties can be realized in high yield, which we expect to allow rapid advancement of chiral nanomaterials research.

Recently, many experimental and theoretical efforts are being intensified to develop high-performance catalysts for electrochemical CO 2 conversion. Beyond the catalyst material screening, it is also critical to optimize the surrounding reaction medium. From vast experiments, inclusion of room-temperature ionic liquid (RTIL) in the electrolyte is found to be beneficial for CO 2 conversion; however, there is no unified picture of the role of RTIL, prohibiting further optimization of the reaction medium. Using a state-of-the-art multiscale simulation, we here unveil the atomic origin of the catalytic promotion effect of RTIL during CO 2 conversion. Unlike the conventional belief, which assumes a specific intermolecular coordination by the RTIL component, we find that the promotion effect is collectively manifested by tuning the reaction microenvironment. This mechanism suggests the critical importance of the bulk properties (e.g., resistance, gas solubility and diffusivity, viscosity, etc.) over the detailed chemical variations of the RTIL components in designing the optimal electrolyte components, which is further supported by our experiments. This fundamental understanding of complex electrochemical interfaces will help in the development of more advanced electrochemical CO 2 conversion catalytic systems in the future.

Intercalation phenomena of gas molecules in the interlayer of graphene oxide have been investigated using CO2, CH4, H2, and N2 gases. Intercalation of gas molecules is highly affected by the affinity between the hydrophilic surface of GO and target molecules. Among tested gases, CO2 can only be intercalated. Furthermore, the swelling of interlayer changed the intercalation phenomena. Amounts of intercalated gases are significantly enhanced, and all the gases can be intercalated by retarded dynamics of intercalated water.

Porous materials have provided us unprecedented opportunities to develop emerging technologies such as molecular storage systems and separation mechanisms. Pores have also been used as supports to contain gas hydrates for the application in gas treatments. Necessarily, an exact understanding of the properties of gas hydrates in confining pores is important. Here, we investigated the formation of CO2, CH4 and N2 hydrates in non-interlamellar voids in graphene oxide (GO), and their thermodynamic behaviors. For that, low temperature XRD and P-T traces were conducted to analyze the water structure and confirm hydrate formation, respectively, in GO after its exposure to gaseous molecules. Confinement and strong interaction of water with the hydrophilic surface of graphene oxide reduce water activity, which leads to the inhibited phase behavior of gas hydrates.

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Ionic liquids (ILs) provide an attractive medium for various chemical and redox reactions, where they are generally regarded as hydrophobic. However, Seddon et al. discovered that 4−10 wt % water absorbs into ILs that contain bulky anions, and Cammarata et al. found that the molecular state of water in ILs is dramatically different from that of bulk liquid water or that of water vapor. To determine the microstructure of water incorporated into ILs and the impact on properties, we carried out first-principlesbased molecular dynamics simulations. We find water in three distinct phases depending on water content, and that the transport properties depend on the nature of the water phases. These results suggest that the optimal water content is ∼10% mole fraction of water molecules (∼1.1 wt %) for applications such as nonvolatile electrolytes for dye-sensitized solar cells (DSSCs). This suggests a strategy for improving the performance of IL DSSC by replacing water with additives that would play the same role as water (since too much water can deteriorate performance at the anode−dye interface).

Solid state calcium ferrite formation reactions between different kinds of iron oxides and CaO under various pO 2 at 1 273 K have been investigated. The calcium ferrite formation rates are evaluated by using thermogravimetric method. The phase identification and quantification of calcium ferrites in the experiment have been carried out by using X-ray diffraction method (the Rietveld method