No abstract

Herein, we demonstrate the ultraviolet (UV) light activated high-performance room-temperature NO gas sensor based on nitrogen-doped graphene quantum dots (NGQDs)decorated TiO 2 hybrid structure. TiO 2 employed in the form of {001} facets exposed rectangular nanoplate morphology, which is highly reactive for the adsorption of active oxygen species. NGQD layers are grown on TiO 2 nanoplates by graphitization of precursors via hydrothermal treatment. The decoration of NGQDs on the TiO 2 surface dramatically enhanced the efficiency of gas and carriers exchange, charge carrier separation and transportation, and oxygen vacancies, which eventually improved the sensing performance. At room temperature, the TiO 2 @ NGQDs hybrid structure exhibited a response of 12.0% to 100 ppm NO, which is 4.8 times higher compared to that of pristine TiO 2 nanoplates. The response of TiO 2 @NGQDs hybrid structure is further upgraded by employing the ultraviolet light illumination and manipulating the operating temperature. Under the UV (λ = 365 nm) illumination at room temperature, the hybrid structure response escalated to ∼31.1% for 100 ppm NO. On the other hand, the tailoring of working temperature yielded a response of ∼223% at an optimum operating temperature of 250 °C. The NO gas-sensing mechanism of TiO 2 @NGQDs nanoplate's hybrid structure sensors under UV illumination and different working temperatures is discussed.

Hexamethyleneimine, 1-methylpiperidine, 2-methylpiperidine, 3-methylpiperidine, and 4-methylpiperidine as isomers of C6H13N were revealed as new sH clathrate hydrate forming molecules. They show fully soluble characteristics to water, whereas already known sH formers such as methylcyclohexane and 2,2-dimethylbutane (neohexane) are immiscible or very slightly soluble to water. The L–H–V equilibrium P–T behavior of these new sH clathrate hydrates shows a tendency to shift to much milder conditions than already known ones. We particularly note that 1-methylpiperidine appears to be the best for promotion. To verify the distribution of CH4 molecules and crystal structure of clathrate hydrates, 600 MHz solid-state NMR, Raman spectroscopy, and XRD pattern analysis were conducted. These noticeable properties of new formers are expected to open new research fields to the hydrate community and contribute to hydrate-based technological applications with high energy efficiency.

A schematic of selective electrochemical CO2 conversion to multicarbon alcohols on N-doped porous carbon-supported Cu catalysts via a two-site mechanism is shown.

The direct recovery of methane from gas hydrate‐bearing sediments is demonstrated, where a gaseous mixture of CO2 + N2 is used to trigger a replacement reaction in complex phase surroundings. A one‐dimensional high‐pressure reactor (8 m) was designed to test the actual aspects of the replacement reaction occurring in natural gas hydrate (NGH) reservoir conditions. NGH can be converted into CO2 hydrate by a “replacement mechanism,” which serves double duty as a means of both sustainable energy source extraction and greenhouse gas sequestration. The replacement efficiency controlling totally recovered CH4 amount is inversely proportional to CO2 + N2 injection rate which directly affecting solid ‐ gas contact time. Qualitative/quantitative analysis on compositional profiles at each port reveals that the length more than 5.6 m is required to show noticeable recovery rate for NGH production. These outcomes are expected to establish the optimized key process variables for near future field production tests. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1004–1014, 2015