mart windows constructed of semiconducting electrochromic materials on conductive glass have been widely used in the energy-saving glass industry. 1,2 However, these smart windows typically exhibit low visible transmittance in the transparent state, reducing their usefulness in some applications. In general, the visible transmittance of electrochromic glass in the transparent state (60À70%) is much lower than that of regular window glass (>80%), 3 delivering a less comfortable visual environment in buildings. Currently, antireflective (AR)-coating technologies have been aimed at improving the light transmittance and visual appearance of smart windows. 3À5 However, this additional AR-coating process is a significant extra expense for fabricating electrochromic glasses. Hence, a great challenge for scientists is to develop a one-step fabricating technique for creating a semiconducting layer with both AR and electrochromic properties.Chemically stable anatase TiO 2 nanocrystals with tetragonal symmetry, formed from TiO 6 octahedra, is the most promising material currently being used in electrochromism studies because the vacant sites formed by the shared edges are large enough to accommodate H þ and Li þ ions. 6,7 Also, anatase TiO 2 nanoparticles (NPs) and nano thin films have been proven to serve well as an AR layer for Si, VO 2 , and InP substrates due to their suitable refractive indices of 2.1À2.3. 8À10 However, the refractive index of a TiO 2 AR layer on glass-based substrates should be 1.2À1.4 according to the relationship n f = (n 0 n s ) 1/2 , 11 where n f , n 0 , and n s are the refractive indices of the AR layer, air, and the substrate, respectively, and the refractive indices of typical conductive glasses (i.e., fluorine-doped tin oxide (FTO) or Sn-doped indium oxide, tin-doped indium oxide (ITO) glass) are closer to 1.5À2. 12,13 Several different approaches have been attempted to reduce the refractive index of TiO 2 . Among these methods, Xi et al. reported that the refractive index of a TiO 2 nanorod (NR) layer on aluminum nitride substrates can be controlled in a way that reduces the refractive index from 2.7 to 1.3 by changing the vapor-deposition incident angle using the oblique-angle deposition (OAD) method. 14 This finding indicates that the TiO 2 NR layer, consisting of obliquely standing, porous nanostructures, is the key to effectively reducing the

A new 3D TNW-AuNP plasmonic electrode consists of antireflective (AR) TiO2 nanowires (TNWs) (∼600 nm thickness) serving as light-harvesting antennae coupling with Au nanoparticles (NPs). A huge red-shift of 55 nm is observed in surface plasmon spectra for the Au (11 nm) plasmonic electrode that has 11 nm size Au NPs, whereby (111) lattice planes have a specific bonding with the TiO2 (101) planes. Remarkable red-shift is mainly attributed to the localized electric field improvement resulting from the plasmonic coupling effect between the Au NPs and the Au-TiO2 hybrids. After TiCl4 treatment, this favorable Au (11 nm) nanostructure takes advantage of harvesting photons to increase the conversion efficiency of dye-sensitized solar cells (DSSCs) from 6.25% to 9.73%.

The green synthesis of nanowired photocatalyst composed of carbon quantum dots-titanium hybrid-semiconductors, CQDs/TiO2, are reported. Where graphite-based CQDs with a size less than 5 nm are directly synthesized in pure water electrolyte by a one-step electrochemistry approach and subsequently electrodeposited onto as-prepared TiO2 nanowires through a voltage-driven reduction process. Electron paramagnetic resonance studies show that the CQDs can generate singlet oxygen and/or oxygen radicals to decompose the kinetic H2O2 intermediate species upon UV light illumination. With the effect of peroxidase-like CQDs, photocurrent density of CQDs/TiO2 is remarkably enhanced by a 6.4 factor when compared with that of as-prepared TiO2.

Three-dimensional (3D) spinel-type MnO 2 has attracted extensive interest as a potential electrode material for supercapacitors in order to meet cost/performance requirements of power supplies. In this study, MnO 2 microspheres (MS-MnO 2 ) with a 3D spinel phase and 0.5−4.0 μm size were constructed from small MnO 2 nanoparticles by a rapid and facile solvothermal process in which tetraethylammonium (TEA) was used as the template. The properties of the synthesized spinel MS-MnO 2 for use in supercapacitors were investigated by cyclic voltammetry and galvanostatic charge/discharge measurements using a three-electrode system in a neutral 1 M Na 2 SO 4 electrolyte. The synthesized spinel MS-MnO 2 exhibited faster charge/discharge rates and higher capacitance than commercial MnO 2 materials. The obtained results showed that the as-prepared spinel MS-MnO 2 possessed good specific capacitance (SC) of ∼190 F/g at 0.5 A/g. The spinel MS-MnO 2 also exhibited excellent SC retention and Coulombic efficiency of ∼100% and ∼95%, respectively, after 1000 cycles at 1 A/g, suggesting its potential application in supercapacitors. In addition, manganese oxides with large cavities were obtained through postannealing treatment and showed their potential for use in energy-storage devices, energy-conversion systems, catalysts, and sensors.

A novel, sandwich-layered Ti/TiO2/Ti/fluorine-doped tin oxide (FTO) architecture is reported. The Ti layers play a critical role in the formation of long pear-necklace chains made of interconnected TiO2 nanoparticles. The chains interpenetrate a network structure on FTO glass substrates under alkaline hydrothermal-processing conditions. A significant enhancement in the photocurrent density of dye-sensitized solar cells employing non-volatile polymer-based electrolytes is obtained

In this study, an anatase/rutile mixed-phase titanium dioxide (TiO2) hierarchical network deposited with Au nanoparticles (Au/TiO2 ARHN) was synthesized using a facile hydrothermal method followed by a simple calcination step. Such a unique structure was designed for improving the light harvest, charge transportation/separation, and the performance of photo-electro-chemical (PEC) cells. The properties of the as-synthesized Au/TiO2 ARHN in PEC cells were investigated by electrochemical measurements using a three-electrode system in a 1 M NaOH electrolyte. Remarkably, a 4.5-folds enhancement of the photocurrent for Au/TiO2 ARHN was observed as compared to that for TiO2 nanowire (NW), under AM1.5G solar illumination, suggesting its potential application in PEC cells. A mechanism has been proposed to explain the high photocurrent of Au/TiO2 ARHN in PEC water splitting.

A 3-dimensional chain-network anatase/TiO2 (B) was obtained via the basic hydrothermal treatment of a sandwich Ti/TiO2/Ti film on a glass substrate that was prepared from 16 nm anatase TiO2 nanoparticles. The Ti film was converted to the TiO2 (B) phase in a Teflon vessel containing a 10 M NaOH aqueous solution that was encapsulated in a stainless-steel autoclave and heated at 130 °C for 2 h. The TiO2 (B) then served as a binder layer that enabled the formation of pearl-necklace chains made of anatase TiO2 nanoparticles, and these chain-like structures thoroughly interpenetrated into the textured layer. Decomposition tests using methylene blue indicated that the chain-network anatase/TiO2 (B) mixed-phase film had a photocatalytic half-life that was 0.84 and 0.69 times shorter than those of as-prepared anatase TiO2 and P25, respectively. In addition, the intensity of the room temperature photoluminescence spectra of anatase TiO2 was 2.55-fold higher than that of the chain-network anatase/TiO2 (B). We thus conclude that the remarkable photocatalytic activity of the chain-network anatase/TiO2 (B) is attributed to the chain-network structural characteristics and a synergistic effect of the matching band gap potentials, which increases the transfer of photogenerated electrons and reduces electron-hole recombination.

Schematic of Pt-loaded TiO2@P-g-C3N4 2D/2D heterojunction structure and the proposed mechanism of charge transfer for photocatalytic H2 evolution.