High thermoelectric figure of merit of porous Si nanowires from 300 to 700 K

Thermoelectrics operating at high temperature can cost-effectively convert waste heat and compete with other zero-carbon technologies. Among different high-temperature thermoelectrics materials, silicon nanowires possess the combined attributes of cost effectiveness and mature manufacturing infrastructures. Despite significant breakthroughs in silicon nanowires based thermoelectrics for waste heat conversion, the figure of merit (ZT) or operating temperature has remained low. Here, we report the synthesis of large-area, wafer-scale arrays of porous silicon nanowires with ultra-thin Si crystallite size of ~4 nm. Concurrent measurements of thermal conductivity (κ), electrical conductivity (σ), and Seebeck coefficient (S) on the same nanowire show a ZT of 0.71 at 700 K, which is more than ~18 times higher than bulk Si. This ZT value is more than two times higher than any nanostructured Si-based thermoelectrics reported in the literature at 700 K. Experimental data and theoretical modeling demonstrate that this work has the potential to achieve a ZT of ~1 at 1000 K.

The role of nanotechnology in the design of materials for Lithium-ion battery

With the growing market of electric vehicle (EV) in recent years, breakthroughs on components of the vehicle, especially the lithium-ion batteries (LIBs) recharging system, have been made by the introduction development of nanotechnology of the cathode and anode of the battery to have high energy and power density, low cost, stableness, and improved capacity reservation performance. The current developments of the popular various cathode materials, LiCoO2, LiMn2O4, and high Ni-rich materials, and anode materials, nanostructured-Si, SnO2, and lithium titanium oxide, are discussed and reviewed with both advantages, and challenges, and potential improvement list. Progress in improving the characteristics of lithium-ion battery LIBs has been made due to nanotechnology's microstructure modification. Further experiments development for on the material of LIBs of lithium-ion battery by modifying nanostructure need to be conducted and studied for EV recharging system to achieve the expected characteristics.

Surface-Enhanced IR-Absorption Microscopy of Staphylococcus aureus Bacteria on Bactericidal Nanostructured Si Surfaces

Surface-enhanced IR absorption (SEIRA) microscopy was used to reveal main chemical and physical interactions between Staphylococcus aureus bacteria and different laser-nanostructured bactericidal Si surfaces via simultaneous chemical enhancement of the corresponding IR-absorption in the intact functional chemical groups. A cleaner, less passivated surface of Si nanoripples, laser-patterned in water, exhibits much stronger enhancement of SEIRA signals compared to the bare Si wafer, the surface coating of oxidized Si nanoparticles and oxidized/carbonized Si (nano) ripples, laser-patterned in air and water. Additional very strong bands emerge in the SEIRA spectra on the clean Si nanoripples, indicating the potential chemical modifications in the bacterial membrane and nucleic acids during the bactericidal effect.