The present paper describes a new method utilizing rapid anodization to quickly synthesize highquality, high aspect ratio, robust titanium dioxide nanotube powders. TiO 2 nanotube powders, with a typical nanotube outer diameter of approximately 40 nm, wall thickness of approximately 8-15 nm, and length of about 10-35 µm, were synthesized by potentiostatic rapid breakdown anodization of titanium foils in aqueous electrolytes of 0.3 M NaCl or 0.1 M HClO 4 under an applied potential of 20 V. High reactivity and ultrahigh reaction rate are cornerstones responsible for periodic release of TiO 2 nanotubes into solution and formation of a white precipitate of TiO 2 nanotubes. The reaction yield is approximately 4-6 g in less than 3 h, and the approximate cost of the material is $3.50/g, based on the laboratory-scale production. Various characterization techniques, including FESEM, HRTEM, EDX, XRD, XPS, FT-IR, UV-visible diffuse-reflectance, and N 2 adsorption, have been used to probe morphology, microstructure, crystallographic, composition, bond configuration, optical properties, and surface area of the nanotubes. XPS and EDX investigations show that nanotubes formed in NaCl/phosphate electrolyte solutions contain a significant amount of phosphorus species, which strongly affects crystallization and phase transformation of TiO 2 . Namely, phosphate-incorporating nanotubes stabilized the anatase phase, and initiation of the rutile phase was observed at annealing temperatures g700 °C. The resulting nanotube powders have a significant level of OH groups with a band gap ranging from 3.04 to 3.23 eV. Our results indicate that rapid breakdown anodization is highly efficient in the production of good-quality TiO 2 nanotube powders, which makes it an alternative to well-documented conventional methods.

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Reactive ion etching was used to fabricate black-Si over the entire surface area of 4-inch Si wafers. After 20 min of the plasma treatment, surface reflection well below 2% was achieved over the 300-1000 nm spectral range. The spikes of the black-Si substrates were coated by gold, resulting in an island film for surface-enhanced Raman scattering (SERS) sensing. A detection limit of 1 × 10 −6 M (at count rate > 10 2 s −1 . mW −1 ) was achieved for rhodamine 6G in aqueous solution when drop cast onto a ∼ 100-nm-thick Au coating. The sensitivity increases for thicker coatings. A mixed mobile-on-immobile platform for SERS sensing is introduced by using dog-bone Au nanoparticles on the Au/black-Si substrate. The SERS intensity shows a non-linear dependence on the solid angle (numerical aperture of excitation/collection optics) for a thick gold coating that exhibits a 10 times higher enhancement. This shows promise for augmented sensitivity in SERS applications.

Nanoplasmonics recently has emerged as a new frontier of photovoltaic research. Noble metal nanostructures that can concentrate and guide light have demonstrated great capability for dramatically improving the energy conversion efficiency of both laboratory and industrial solar cells, providing an innovative pathway potentially transforming the solar industry. However, to make the nanoplasmonic technology fully appreciated by the solar industry, key challenges need to be addressed; including the detrimental absorption of metals, broadband light trapping mechanisms, cost of plasmonic nanomaterials, simple and inexpensive fabrication and integration methods of the plasmonic nanostructures, which are scalable for full size manufacture. This article reviews the recent progress of plasmonic solar cells including the fundamental mechanisms, material fabrication, theoretical modelling and emerging directions with a distinct emphasis on solutions tackling the above-mentioned challenges for industrial relevant applications.

Multicrystalline silicon solar cells play an increasingly important role in the world photovoltaic market. Boosting the comparatively low energy conversion efficiency of multicrystalline silicon solar cells is of great academic and industrial significance. In this paper, Au nanoparticles of an optimized size, synthesized by the iterative seeding method, were integrated onto industrially available surface-textured multicrystalline silicon solar cells via a dip coating method. Enhanced performance of the light absorption, the external quantum efficiency and the energy conversion efficiency were consistently demonstrated, resulting from the light scattering by the sized-tailored Au nanoparticles placed on the front surface of the solar cells, particularly in the spectral range from 800 to 1200 nm, an enhancement of the external quantum efficiency by more than 11% near λ = 1150 nm and the short-circuit current by 0.93% were both observed. As a result, an increase in the energy conversion efficiency up to 1.97% under the standard testing conditions (25°C, global air mass 1.5 spectrum, 1000 Wm −2) was achieved. This study opens new perspectives for plasmonic nanoparticle applications for photon management in multicrystalline silicon solar cells.