Molybdenum disulfide (MoS2) is a promising non-precious-metal catalyst, but its performance is limited by the density of active sites and poor electrical transport. Its metallic 1T phase possesses higher photoelectrocatalytic activity. Thus, how to efficiently increase the concentration of the 1T phase in the exfoliated two-dimensiaonal (2D) MoS2 nanosheets is an important premise. In this work, we propose a strategy to prepare a 2D heterostructure of MoS2 nanosheets using supercritical CO2-induced phase engineering to form metallic 1T-MoS2. Theoretical calculations and experimental results demonstrate that the introduced CO2 in the 2H-MoS2 host can prompt the transformation of partial 2H-MoS2 lattices into 1T-MoS2. Moreover, the electrical coupling and synergistic effect between 2H and 1T phases can greatly facilitate the efficient electron transfer from the active sites of MoS2, which significantly improves the photocatalytic performance.

As a remarkable class of plasmonic materials, two dimensional (2D) semiconductor compounds have attracted attention owing to their controlled manipulation of plasmon resonances in the visible light spectrum, which outperforms conventional noble metals. However, tuning of plasmonic resonances for 2D semiconductors remains challenging. Herein, we design a novel method to obtain amorphous molybdenum oxide (MoO ) nanosheets, in which it combines the oxidation of MoS and subsequent supercritical CO -treatment, which is a crucial step for the achievement of amorphous structure of MoO . Upon illumination, hydrogen-doped MoO exhibits tuned surface plasmon resonances in the visible and near-IR regions. Moreover, a unique behavior of the amorphous MoO nanosheets has been found in an optical biosensing system; there is an optimum plasmon resonance after incubation with different BSA concentrations, suggesting a tunable plasmonic device in the near future.

alternative clean energy supplies and pollution-free technologies turns out to be high priority. [1,2] The CO 2 reduction project plays a pivotal role in response to the concerns because of its capability of exhausted gas consumption and combustible fuels generation. [3][4][5][6] Gas-phase thermal reduction of CO 2 to CO via endothermic reverse water gas shift (RWGS) reaction becomes an attractive strategy on account of abundant accessibility of thermal catalytic active sites. On the same time removing excessive CO 2 in atmosphere, the emitted CO can be also utilized directly as the feedstock for further fuel manufacturing (e.g., via the Fischer-Tropsch process). [7][8][9][10] However, to achieve purposeful CO 2 conversion, massive nonrenewable energy is indispensable to be invested in the reaction. Compared with traditional energy, alternative inexhaustible energy input has been discovered via photothermal process which effectively utilizes full spectrum of sunlight to lead accurate heating location and instantaneously raise the surface temperature of the catalysts. [11][12][13][14][15][16] Indium-oxide-based materials are a typical thermal catalyst with potential prospect for photothermal reduction of CO 2 . Its catalytic active sites promote the adsorption and activation for thermochemical CO 2 hydrogenation, [17,18] but the wide band (2.8 eV) is unfavorable for photothermal conversion for a long time. In order to expanding the limited optical adsorption of In 2 O 3 under sunlight, there have been persistent efforts to alter the material composition of In 2 O 3 , such as element doping, [19] precious metals supporting, [20] and nanostructured substance coating. [21] For example, when Bi metallic dopants are introduced, the optical adsorption can be modified as the result of electronic hybridization between Bi 6s and O 2p orbitals, upwardly shifting the valence band (VB) and consequently reducing bandgap. [22] Recently, Ozin group report a hybrid catalyst consisting of a vertically aligned silicon nanowire (SiNW) support evenly coated by In 2 O 3−x (OH) y nanoparticles to minimized reflection losses and enhanced light trapping within the SiNW support. [23] Basically, eminent photothermal catalysts are composite materials, but the pure ones have not come up yet. In order to construct various active sites to activate wide range of reactants, designing and modulating Photothermal CO 2 reduction technology has attracted tremendous interest as a solution for the greenhouse effect and energy crisis, and thereby it plays a critical role in solving environmental problems and generating economic benefits. In 2 O 3−x has emerged as a potential photothermal catalyst for CO 2 conversion into CO via the light-driven reverse water gas shift reaction. However, it is still a challenge to modulate the structural and electronic characteristics of In 2 O 3 to enhance photothermocatalytic activity synergistically. In this work, a novel route to activate inert In(OH) 3 into 2D black In 2 O 3−x nanosheets via photoinduced defect eng...

As coronavirus disease 2019 (COVID-19) continues to spread, a detailed understanding on the transmission mechanisms is of paramount importance. The disease transmits mainly through respiratory droplets and aerosol. Although models for the evaporation and trajectory of respiratory droplets have been developed, how the environment impacts the transmission of COVID-19 is still unclear. In this study, we investigate the propagation of respiratory droplets and aerosol particles generated by speech under a wide range of temperatures (0–40 °C) and relative humidity (0–92%) conditions. We show that droplets can travel three times farther in low-temperature and high-humidity environment, whereas the number of aerosol particles increases in high-temperature and low-humidity environments. The results also underscore the importance of proper ventilation, as droplets and aerosol spread significantly farther in airstreams. This study contributes to the understanding of the environmental impact on COVID-19 transmission.

MoS2 nanosheets with polydispersity of the lateral dimensions from natural mineral molybdenite have been prepared in the emulsions microenvironment built by the water/surfactant/CO2 system. The size, thickness, and atomic structure are characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), and laser-scattering particle size analysis. Meanwhile, by the analysis of photoluminescence spectroscopy and microscope, the MoS2 nanosheets with smaller lateral dimensions exhibit extraordinary photoluminescence properties different from those with relatively larger lateral dimensions. The discovery of the excitation dependent photoluminescence for MoS2 nanosheets makes them potentially of interests for the applications in optoelectronics and biology. Moreover, we demonstrate that the fabricated MoS2 nanosheets can be a nontoxic fluorescent label for cell-targeted labeling application.