Simple synthesis of K/P co-doped graphitic carbon nitride to enhance photocatalytic performance under simulated solar irradiation.

The doping or co-doping of graphitic carbon nitride (g-CN) with other elements is a useful modification technique that overcomes the disadvantages of the base material and enhances its photocatalytic performance. In this study, K and P were successfully incorporated into g-CN using a one-step, single-precursor (KHPO) synthesis method. The incorporation of K and P was confirmed using energy-dispersive X-ray spectrometry and wavelength-dispersive X-ray fluorescence spectrometry.

Rapid Surface Reconstruction of InS Photoanode via Flame Treatment for Enhanced Photoelectrochemical Performance.

Surface reconstruction, reorganizing the surface atoms or structure, is a promising strategy to manipulate materials' electrical, electrochemical, and surface catalytic properties. Herein, a rapid surface reconstruction of indium sulfide (InS) is demonstrated via a high-temperature flame treatment to improve its charge collection properties. The flame process selectively transforms the InS surface into a diffusionless InO layer with high crystallinity.

Graphitic-carbon-nitride-hydrophilicity-dependent photocatalytic degradation of antibiotics with different log K.

The surface hydrophilicity of a photocatalyst is an important factor that directly influences its interactions with organic pollutants and significantly impacts its degradation. In this study, we investigated the impact of increased hydrophilicity of g-CN (CN) by alkaline solvothermal treatment on the degradations of three antibiotics (oxytetracycline (OTC), oxolinic acid (OA), and sulfamethoxazole (SMX)) with different log K values. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and Fourier-transform infrared (FT-IR) spectroscopy showed no significant differences in the morphology, crystalline structure, and surface functional groups of CN after alkaline solvothermal treatment (Nv-HPCN).

Facile synthesis of N vacancy g-CN using Mg-induced defect on the amine groups for enhanced photocatalytic •OH generation.

Photocatalysis offers opportunities to degrade recalcitrant organic pollutants without adding treatment chemicals. Nitrogen (N) vacancy is an effective point-defect engineering strategy to mitigate electron-hole recombination and facilitate hydroxyl radical (•OH) production via superoxide radical (O) generation during photocatalytic application of graphitic carbon nitride (g-CN). Here, we report a novel strategy for fabrication of N-vacancy-rich g-CN (NvrCN) via post-solvothermal treatment of Mg-doped g-CN.

Ascorbic Acid Attenuates Lead-Induced Alterations in the Synapses in the Developing Rat Cerebellum.

We evaluated the effect of lead (Pb) and ascorbic acid treatment of pregnant female rats on cerebellar development in pups. Pb was administered in drinking water (0.2% Pb acetate), and ascorbic acid (100 mg/kg) was administered through oral intubation.

Three-Dimensional Hetero-Integration of Faceted GaN on Si Pillars for Efficient Light Energy Conversion Devices.

An important pathway for cost-effective light energy conversion devices, such as solar cells and light emitting diodes, is to integrate III-V (e.g., GaN) materials on Si substrates.

BiVO/WO/SnO Double-Heterojunction Photoanode with Enhanced Charge Separation and Visible-Transparency for Bias-Free Solar Water-Splitting with a Perovskite Solar Cell.

Coupling dissimilar oxides in heterostructures allows the engineering of interfacial, optical, charge separation/transport and transfer properties of photoanodes for photoelectrochemical (PEC) water splitting. Here, we demonstrate a double-heterojunction concept based on a BiVO/WO/SnO triple-layer planar heterojunction (TPH) photoanode, which shows simultaneous improvements in the charge transport (∼93% at 1.23 V vs RHE) and transmittance at longer wavelengths (>500 nm).

Reduced Graphene Oxide/Mesoporous TiO2 Nanocomposite Based Perovskite Solar Cells.

We report on reduced graphene oxide (rGO)/mesoporous (mp)-TiO2 nanocomposite based mesostructured perovskite solar cells that show an improved electron transport property owing to the reduced interfacial resistance. The amount of rGO added to the TiO2 nanoparticles electron transport layer was optimized, and their impacts on film resistivity, electron diffusion, recombination time, and photovoltaic performance were investigated. The rGO/mp-TiO2 nanocomposite film reduces interfacial resistance when compared to the mp-TiO2 film, and hence, it improves charge collection efficiency.

Enhanced Photocatalytic Activity of Ultrathin Ba5Nb4O15 Two-Dimensional Nanosheets.

Anisotropic two-dimensional (2D) nanosheets of the layered perovskite, Ba5Nb4O15, with thicknesses of 5-10 nm and lateral sizes of 300-1200 nm, were synthesized by a hydrothermal route. The influences of the 2D morphology of the material on the crystal and electronic structures, light absorption properties, and photocatalytic activity were investigated. The ultrathin nanosheets showed much-enhanced photocatalytic activity compared to both thick nanosheets (∼30 nm) and micrometer-sized particles for the evolution of H2 from water splitting under UV light illumination.

Epitaxial 1D electron transport layers for high-performance perovskite solar cells.

We demonstrate high-performance perovskite solar cells with excellent electron transport properties using a one-dimensional (1D) electron transport layer (ETL). The 1D array-based ETL is comprised of 1D SnO2 nanowires (NWs) array grown on a F:SnO2 transparent conducting oxide substrate and rutile TiO2 nanoshells epitaxially grown on the surface of the 1D SnO2 NWs. The optimized devices show more than 95% internal quantum yield at 750 nm, and a power conversion efficiency (PCE) of 14.

Highly Efficient Solar Water Splitting from Transferred TiO2 Nanotube Arrays.

We report a synergistic effect of flame and chemical reduction methods to maximize the efficiency of solar water splitting in transferred TiO2 nanotube (TNT) arrays on a transparent conducting oxide (TCO) substrate. The flame reduction method (>1000 °C) leads to few oxygen vacancies in the anatase TNT arrays, but it exhibits unique advantages for excellent interfacial characteristics between transferred TNT arrays and TCO substrates, which subsequently induce a cathodic on-set potential shift and sharp photocurrent evolution. By contrast, the employed chemical reduction method for TNT arrays/TCO gives rise to an abrupt increase in photocurrent density, which results from the efficient formation of oxygen vacancies in the anatase TiO2 phase, but a decrease in charge transport efficiency with increasing chemical reduction time.

Direct Low-Temperature Growth of Single-Crystalline Anatase TiO2 Nanorod Arrays on Transparent Conducting Oxide Substrates for Use in PbS Quantum-Dot Solar Cells.

We report on the direct growth of anatase TiO2 nanorod arrays (A-NRs) on transparent conducting oxide (TCO) substrates that can be directly applied to various photovoltaic devices via a seed layer mediated epitaxial growth using a facile low-temperature hydrothermal method. We found that the crystallinity of the seed layer and the addition of an amine functional group play crucial roles in the A-NR growth process. The A-NRs exhibit a pure anatase phase with a high crystallinity and preferred growth orientation in the [001] direction.

Anionic ligand assisted synthesis of 3-D hollow TiO2 architecture with enhanced photoelectrochemical performance.

Hollow structured materials have shown great advantages for use in photoelectrochemical devices. However, their poor charge transport limits overall device performance. Here, we report a unique 3-D hollow architecture of TiO2 that greatly improves charge transport properties.

Transparent-conducting-oxide nanowire arrays for efficient photoelectrochemical energy conversion.

We report one dimensional (1-D) transparent-conducting-oxide arrays coated with light-absorbing semiconductors to simultaneously maximize light harvesting and charge collection in a photoelectrochemical (PEC) system. Tin-doped indium oxide (ITO) nanowire (NW) arrays are prepared on ITO thin-film substrates as the transparent-conducting-oxide, and TiO2 or CdSe/CdS/TiO2 thin layers were coated on the ITO NW arrays as the solar light-absorbing layers. The optimal PEC performance, 0.

Sol-flame synthesis of cobalt-doped TiO2 nanowires with enhanced electrocatalytic activity for oxygen evolution reaction.

Doping nanowires (NWs) is of crucial importance for a range of applications due to the unique properties arising from both impurities' incorporation and nanoscale dimensions. However, existing doping methods face the challenge of simultaneous control over the morphology, crystallinity, dopant distribution and concentration at the nanometer scale. Here, we present a controllable and reliable method, which combines versatile solution phase chemistry and rapid flame annealing process (sol-flame), to dope TiO2 NWs with cobalt (Co).

Simultaneously efficient light absorption and charge separation in WO3/BiVO4 core/shell nanowire photoanode for photoelectrochemical water oxidation.

We report a scalably synthesized WO3/BiVO4 core/shell nanowire photoanode in which BiVO4 is the primary light-absorber and WO3 acts as an electron conductor. These core/shell nanowires achieve the highest product of light absorption and charge separation efficiencies among BiVO4-based photoanodes to date and, even without an added catalyst, produce a photocurrent of 3.1 mA/cm(2) under simulated sunlight and an incident photon-to-current conversion efficiency of ∼ 60% at 300-450 nm, both at a potential of 1.

Rapid and controllable flame reduction of TiO2 nanowires for enhanced solar water-splitting.

We report a new flame reduction method to generate controllable amount of oxygen vacancies in TiO2 nanowires that leads to nearly three times improvement in the photoelectrochemical (PEC) water-splitting performance. The flame reduction method has unique advantages of a high temperature (>1000 °C), ultrafast heating rate, tunable reduction environment, and open-atmosphere operation, so it enables rapid formation of oxygen vacancies (less than one minute) without damaging the nanowire morphology and crystallinity and is even applicable to various metal oxides. Significantly, we show that flame reduction greatly improves the saturation photocurrent densities of TiO2 nanowires (2.

Peel-and-stick: mechanism study for efficient fabrication of flexible/transparent thin-film electronics.

Peel-and-stick process, or water-assisted transfer printing (WTP), represents an emerging process for transferring fully fabricated thin-film electronic devices with high yield and fidelity from a SiO2/Si wafer to various non-Si based substrates, including papers, plastics and polymers. This study illustrates that the fundamental working principle of the peel-and-stick process is based on the water-assisted subcritical debonding, for which water reduces the critical adhesion energy of metal-SiO2 interface by 70 ~ 80%, leading to clean and high quality transfer of thin-film electronic devices. Water-assisted subcritical debonding is applicable for a range of metal-SiO2 interfaces, enabling the peel-and-stick process as a general and tunable method for fabricating flexible/transparent thin-film electronic devices.

Morphological control of heterostructured nanowires synthesized by sol-flame method.

Heterostructured nanowires, such as core/shell nanowires and nanoparticle-decorated nanowires, are versatile building blocks for a wide range of applications because they integrate dissimilar materials at the nanometer scale to achieve unique functionalities. The sol-flame method is a new, rapid, low-cost, versatile, and scalable method for the synthesis of heterostructured nanowires, in which arrays of nanowires are decorated with other materials in the form of shells or chains of nanoparticles. In a typical sol-flame synthesis, nanowires are dip-coated with a solution containing precursors of the materials to be decorated, then dried in air, and subsequently heated in the post-flame region of a flame at high temperature (over 900°C) for only a few seconds.

Codoping titanium dioxide nanowires with tungsten and carbon for enhanced photoelectrochemical performance.

Recent density-functional theory calculations suggest that codoping TiO2 with donor-acceptor pairs is more effective than monodoping for improving photoelectrochemical water-splitting performance because codoping can reduce charge recombination, improve material quality, enhance light absorption and increase solubility limits of dopants. Here we report a novel ex-situ method to codope TiO2 with tungsten and carbon (W, C) by sequentially annealing W-precursor-coated TiO2 nanowires in flame and carbon monoxide gas. The unique advantages of flame annealing are that the high temperature (>1,000 °C) and fast heating rate of flame enable rapid diffusion of W into TiO2 without damaging the nanowire morphology and crystallinity.

BaSnO3 perovskite nanoparticles for high efficiency dye-sensitized solar cells.

The synthesis of highly crystalline perovskite BaSnO3 nanoparticles for use as photoanode materials in dye-sensitized solar cells (DSSCs) is reported, and the photovoltaic properties of DSSCs based on BaSnO3 nanoparticles (BaSnO3 cells) are demonstrated. The resulting DSSCs exhibit remarkably rapid charge collection and a DSSC fabricated with a BaSnO3 film thickness of 43 µm leads to a high energy conversion efficiency of 5.2 %, which is one of the highest reported for ternary oxide-based DSSCs.

Controlled synthesis and Li-electroactivity of rutile TiO2 nanostructure with walnut-like morphology.

Herein, we report on the synthesis of phase-pure rutile walnut-like TiO(2) (W-TiO(2)) spheres composed of single-crystalline nanorod-building blocks using a surfactant-free non-aqueous acidic modified "benzyl alcohol route". Based on the various HCl concentration- and reaction time-dependent experiments, an effect of hydrochloric acid on the phase formation mechanism in a non-aqueous system is suggested. As anodes for Li-ion batteries, the W-TiO(2) sphere electrodes exhibited superior cycling performance at a rate of 0.

Improved quantum efficiency of highly efficient perovskite BaSnO₃-based dye-sensitized solar cells.

Ternary oxides are potential candidates as an electron-transporting material that can replace TiO₂ in dye-sensitized solar cells (DSSCs), as their electronic/optical properties can be easily controlled by manipulating the composition and/or by doping. Here, we report a new highly efficient DSSC using perovskite BaSnO₃ (BSO) nanoparticles. In addition, the effects of a TiCl₄ treatment on the physical, chemical, and photovoltaic properties of the BSO-based DSSCs are investigated.

Peel-and-stick: fabricating thin film solar cell on universal substrates.

Fabrication of thin-film solar cells (TFSCs) on substrates other than Si and glass has been challenging because these nonconventional substrates are not suitable for the current TFSC fabrication processes due to poor surface flatness and low tolerance to high temperature and chemical processing. Here, we report a new peel-and-stick process that circumvents these fabrication challenges by peeling off the fully fabricated TFSCs from the original Si wafer and attaching TFSCs to virtually any substrates regardless of materials, flatness and rigidness. With the peel-and-stick process, we integrated hydrogenated amorphous silicon (a-Si:H) TFSCs on paper, plastics, cell phone and building windows while maintaining the original 7.