Pressure retarded osmosis (PRO) generates energy from salinity gradients. Reverse salt flux through a semi-permeable PRO membrane reduces the energy efficiency. We demonstrate for the first time the direct conversion of the reverse salt flux into electrochemical potential, recovering >7% positive net power using a single electrochemical PRO membrane.
We report the direct
chemical vapor deposition of graphitic carbon-encapsulating carbonate
apatite nanowires (GCECANs)/hexagonal portlandite-phased Ca(OH)2 hybrid structures from CaCO3 powder at 900 °C.
The formation mechanism of the GCECANs is investigated in detail through
a structural and morphological characterization of the final products.
Spectroscopic analyses elucidate the effect of H2 concentration
in the reactor on the transformation of the calcite-phased CaCO3 into vaterite-phased CaCO3 and subsequently portlandite-phased
Ca(OH)2. The results show that GCECANs are formed on the
surface of the derived Ca(OH)2. It is especially remarkable
that a higher H2 concentration results in the precipitated
growth of such hybrid structures. Microscopic images show that GCECANs
20 nm in diameter grew up to 3 μm in length along the direction
corresponding to the [001] plane of the hexagonal apatite crystal.
In addition, the electrical properties of the GCECANs are measured
by using an electrode with 150 nm gap.
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