The demands for green production of hydrogen peroxide have triggered extensive studies in the photocatalytic synthesis, but most photocatalysts suffer from rapid charge recombination and poor 2e − oxygen reduction reaction (ORR) selectivity. Here, a novel composite photocatalyst of cyanorich graphitic carbon nitride g-C 3 N 4 is fabricated in a facile manner by sodium chloride-assisted calcination on dicyandiamide. The obtained photocatalysts exhibit superior activity (7.01 mm h −1 under λ ≥ 420 nm, 16.05 mm h −1 under simulated sun conditions) for H 2 O 2 production and 93% selectivity for 2e − ORR, much higher than that of the state-of-the-art photocatalyst. The porous g-C 3 N 4 with Na dopants and cyano groups simultaneously optimize two limiting steps of the photocatalytic 2e − ORR: photoactivity, and selectivity. The cyano groups can adjust the band structure of g-C 3 N 4 to achieve high activity. They also serve as oxygen adsorption sites, in which local charge polarization facilitates O 2 adsorption and protonation. With the aid of Na + , the O 2 is reduced to produce more superoxide radicals as the intermediate products for H 2 O 2 synthesis. This work provides a facile approach to simultaneously tune photocatalytic activity and 2e − ORR selectivity for boosting H 2 O 2 production, and then paves the way for the practical application of g-C 3 N 4 in environmental remediation and energy supply.
Estrogen induces AQP1 expression by activating ERE in the promoter of the Aqp1 gene, resulting in tubulogenesis of vascular endothelial cells. These results provide new insights into the molecular mechanisms underpinning the angiogenic effects of estrogen.
One of the most pervasive environmental
issues is the frequent
oil spills that happen during oil production and transportation
processes. This global challenge calls for emerging materials that
can effectively separate oil pollutants from water. Here, a facile
and feasible method to fabricate a high-performance oil absorbent
(ODA-rGO@MF) through the coating of octadecylamine-grafted reduced
graphene oxide (ODA-rGO) on the skeleton of commercial melamine foam
(MF) is reported. The resultant foam not only possesses the hierarchical
pore structure, superior compressibility, and mechanical stability
of the original foam but also exhibits high water repellency, superhydrophobicity,
and durability under harsh conditions, such as in strongly acidic
(alkaline)
and salty solutions. The superhydrophobicity of ODA-rGO@MF was created
by employing the microarchitecture of MF, forming the rough rGO nanoscale
wrinkles on the foam skeletons and further reducing the surface energy
by octadecylamine (ODA). These fascinating characteristics make the
functionalized foam an excellent oil absorbent with a high absorption
capacity (44–111 times its own weight) and extraordinary recyclability.
More importantly, the inexpensive materials and low-cost fabrication
technique make it possible for large-scale production. Thus, the as-prepared
foam has the potential to be used as a promising absorbent for oil-spill
cleanups.
<p>We report on mooring observations of tidal currents in Prydz Bay, East Antarctica. Tides in Prydz Bay are mixed diurnal-semidiurnal and much weaker than that in the Ross Sea and the Weddell Sea, with the spatial and temporal averaged value of 2.58 cm s<sup>-1</sup> for all the current meter observations over the continental shelf. The major axes of the tidal ellipses are generally aligned south-north, probably steered by the topography. The tidal phases are modulated by both the baroclinic and barotropic tidal components. The averaged tidal kinetic energy can account for a fraction of ~13% with respect to the total kinetic energy at the Amery Ice Shelf calving front during the observing period. The long-term average tidal heat flux across the Amery Ice Shelf calving front is negligible, but the ratio of the tidal heat flux standard deviation to the residual heat flux standard deviation can be up to 41%. We also report on borehole observations of tide-like pulsing of potential temperature and salinity, indicating the indispensable tidal influences in the ice-ocean boundary layer. These mooring and borehole data support that the tidal processes should be highlighted in the investigations of the interaction between the Amery Ice Shelf and ocean.</p>
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