The synergistic effect of enhanced photocatalytic activity and photothermal effect of oxygen-deficient Ni/reduced graphene oxide nanocomposite for rapid disinfection under near-infrared irradiation.

The rational design of high antibacterial efficiency are urgently needed as the occurrence of drug-resistance issues. Hence, Ni/reduced graphene oxide nanocomposite (Ni/rGO) with different amounts of oxygen vacancies were fabricated for efficient disinfection. The optimized Ni/rGO (A100) exhibited highly effective inactivation efficacy of 99.6% and 99.5% against Escherichia coli and Bacillus subtilis within 8 min near-infrared (NIR) irradiation through the synergistic effects of photothermal therapy and oxidative damage, which were much higher than single treatment. The A100 nanocomposite achieved an extraordinary photothermal conversion efficiency (35.78%) under the 808 nm irradiation for enhanced photothermal hyperthermia, thereby destroying the cell membrane and accelerating the GSH depletion. The radical scavenger experiment confirmed that •O2- and •OH play the chief role in photodisinfection reaction. Besides, A100 could exert significant damage on the ATP synthesis. The excellent photothermal performance and photocatalytic activity can be attributed to the appropriate oxygen vacancy density, which improves the absorption of NIR light and facilitates the separation of photogenerated electron-hole pairs. Besides, the higher NiO content of A100 contributed to improving the photocatalytic effect. Our work demonstrated a promising strategy for efficient water pollution purification caused by pathogenic bacteria.

Less is more: biological effects of NiSe2/rGO nanocomposites with low dose provide new insight for risk assessment.

Nickel selenide nanomaterials (NiSe2 NMs) with different vacancies demonstrated high catalytic activity as electrocatalyst in oxygen evolution reaction. As the growing needs of the industrial applications in electrocatalyst, the increased occupational exposure and environmental releasing of NMs would be unavoidable. While, much efforts have been made to evaluate the ecological safety of such engineered NMs at unrealistically high concentrations, failed to provide the comprehensively guideline for exposure thresholds. To supplement the current knowledge gap, we testified the cytotoxicity of NiSe2/rGO nanocomposites with different surface defects under more realistic exposure mode. Compared with the short-term exposure and repetitive exposure, rat lung macrophages exhibited the augmented oxidative stress, dysfunction of mitochondria, damage of DNA and disorder of calcium homeostasis under the long-term NiSe2/rGO exposure. Noteworthily, no significant differences could be found between the NiSe2/rGO with different surface defects, indicated that the defect type of NMs were not the accurate predictor for real risk assessment. Collectively, the study provided the real potential toxic effects and exposure thresholds of NMs that might be highly possible industrial produced, and appealed the new insight for risk assessments of engineered NMs under the long-term exposure, which exhibited difference from the traditional evaluation of short-term and repetitive exposure.

Rapid and selective detection of acetone using hierarchical ZnO gas sensor for hazardous odor markers application.

Hierarchical nanostructured ZnO dandelion-like spheres were synthesized via solvothermal reaction at 200°C for 4h. The products were pure hexagonal ZnO with large exposure of (002) polar facet. Side-heating gas sensor based on hierarchical ZnO spheres was prepared to evaluate the acetone gas sensing properties. The detection limit to acetone for the ZnO sensor is 0.25ppm. The response (Ra/Rg) toward 100ppm acetone was 33 operated at 230°C and the response time was as short as 3s. The sensor exhibited remarkable acetone selectivity with negligible response toward other hazardous gases and water vapor. The high proportion of electron depletion region and oxygen vacancies contributed to high gas response sensitivity. The hollow and porous structure of dandelion-like ZnO spheres facilitated the diffusion of gas molecules, leading to a rapid response speed. The largely exposed (002) polar facets could adsorb acetone gas molecules easily and efficiently, resulting in a rapid response speed and good selectivity of hierarchical ZnO spheres gas sensor at low operating temperature.

Enhanced solar water-splitting efficiency using core/sheath heterostructure CdS/TiO2 nanotube arrays.

A novel fabrication route for core/sheath heterostructure CdS/TiO(2) nanotube arrays is proposed using ac electrodeposition for application in photoelectrochemical cells. The morphologies of the CdS/TiO(2) electrodes, which were prepared by electrochemically depositing CdS directly into anodic titanium nanotubes from an electrolyte containing Cd(2+) and S in dimethyl sulfoxide, were characterized by a field emission scanning electron microscope (FESEM). The deposited material was found to be in a hexagonal CdS structure by x-ray diffraction (XRD). The synthesized CdS/TiO(2) electrodes showed much higher photocurrent density in the visible wavelength region than pure TiO(2) nanotube arrays. We demonstrate that ac deposition voltage and time can control the CdS/TiO(2) composite architecture, which is crucial in determining the overall efficiency of the water-splitting reaction. The maximum photocurrent density was obtained with the core/sheath heterostructure CdS/TiO(2) nanotube arrays, which were fabricated by deposition of CdS at 5 V for 30 min with 2.5 microm tube length.