Hydrodynamics of an OWC Device in Irregular Incident Waves Using RANS Model

This research examines the hydrodynamic performance of an oscillating water column device placed over a sloping seabed under the influence of irregular incident waves. The numerical model is based on the Reynolds-veraged Navier–Stokes (RANS) equations with a modified k−ω turbulence model and uses the volume-of-fluid (VOF) approach to monitor the air–water interface. To explore the hydrodynamic performance of the OWC device in actual ocean conditions, the Pierson–Moskowitz (P-M) spectrum was used as the incident wave spectrum, together with the four distinct sea states which occur most often along the western coast of Portugal. The numerical simulation offers a comprehensive velocity vector and streamline profiles inside the OWC device’s chamber during an entire cycle of pressure fluctuation. In addition, the impact of the irregular wave conditions on the free-surface elevation at various places, the pressure drop between the chamber and the outside, and the airflow rate via the orifice per unit width of the OWC device are investigated in detail. The results demonstrate that the amplitudes of the inward and outward velocities via the orifice, free-surface elevations, and flow characteristics are greater for more significant wave heights. Further, it is noticed that the power generation and capture efficiency are higher for a seabed having moderate slopes

Flower-shaped anatase TiO2 mesostructures with excellent photocatalytic properties

10.1039/c3ra45021jRSC Advances431421-1424RSCA

Sustainable Chemical Synthesis for Phosphorus-Doping of TiO₂ Nanoparticles by Upcycling Human Urine and Impact of Doping on Energy Applications

Recently, there has been significant research interest toward sustainable chemical synthesis and processing of nanomaterials. Human urine, a pollutant, requires energy intensive processing steps prior to releasing into rivers and oceans. Upcyling urine has been proposed and practiced as a sustainable process in the past. Doping is one of the foremost processes to elevate the functionality of nanomaterials depending on the applications it is sought for. Phosphorus doping in to TiO₂ nanomaterials has been of research interest over a decade now, that has been chiefly done using acidic precursors. Here we demonstrate, upcycling urine, a sustainable process for phosphorus doping into TiO₂ lattice. Upon doping the changes in morphology, surface chemistry and band gap is studied in detail and compared with undoped TiO₂ that is prepared using deionized water instead of urine. X-ray photoelectron spectroscopy confirmed that the P was replacing Ti in the lattice and exists in P⁵⁺ state with a quantified concentration of 2.5–3 at %. P-doped nanoparticles were almost 50% smaller in size with a lower concentration of surface −OH groups and a band gap increase of 0.3 eV. Finally, impact of these changes on energy devices such as dye-sensitized solar cells and li-ion batteries has been investigated. It is confirmed that P-doping induced surface chemical and band gap changes in TiO₂ affected the solar cell characteristics negatively, while the smaller particle size and possibly wider surface channels improved Li-ion battery performance

Electrospun α-Fe2O3 nanostructures for supercapacitor applications

10.1039/c3ta12352aJournal of Materials Chemistry A13811698-11704JMCA