ABSTRACT
Developing photothermal solar driven membrane distillation (PSDMD) is of great importance in providing fresh water for remote off-grid regions. The production of freshwater through the PSDMD is driven by the temperature difference between feed and distillate sides created via the addition of efficient photothermal nanostructures. Here we proposed nickel sulfides and nickel tellurium nanoparticles (NPs) to be loaded into the polymeric membrane to enhance its performance. Ag and CuSe NPs are also considered for comparison as they are previously used for membrane distillation (MD). Our theoretical approach showed that all of the considered NPs increased the temperature of the PVDF membrane by around a few degrees. NiS and NiTe2 NPs are the most efficient solar light-to-heat converters compared to NiTe and NiS2 NPs due to their efficient absorption over the visible range. PVDF membrane loaded with 25% of NiCs NPs and a porosity of 32% produced a transmembrane vapor flux between 22 and 27 L/m2h under a 10-times-amplified sun intensity. Under the same conditions, the PVDF membrane loaded with CuSe and Ag NPs produced 15 and 18 L/m2h of vapor flux, respectively. The implantation of NPs through the membrane not only increased its surface temperature but also possessed a high porosity which provided a higher distillation and energy efficiency that reached 58% with NiS NPs. Finally, great agreement between our theoretical model and experimental measurement is obtained.
ABSTRACT
We present a theoretical study showing that the exciton emission in the CdSe-CdSe1-xTexcore-alloyed crown heterostructure results from the tunable quasi-type II to pure type II behavior by adjusting the Te to Se ratio. We suggest that the direct crown exciton or interface indirect exciton or a dual emission can be tuned due to the altered conduction band offset. We also found that these different emissions are red-shifted with increasing the nanoplatelets (NPLs) monolayer (ML) thickness due to the quantum confinement effect. The double exciton emission develops caused by the band bowing effect occurring in the alloyed crown. The band bowing is originated from the difference between the bonding nature of the Se and Te orbitals with the Cd orbitals in the conduction band edge states. We also found that the band bowing is sensitive on the alloyed-crown ML thickness and the in-plane strain due to hybridization magnitude between the cation (Cd) and anion (Se, Te). Our results are in accord with the available experimental data. We propose the CdSe-CdSe1-xTexcore-alloyed crown NPLs as a promising contender for the near-infrared-emitting heterostructures preparation used for light-harvesting applications.