2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Semiconductor-based Photocatalytic Hydrogen Generation

Jenny Schneider,*,† Masaya Matsuoka,‡ Masato Takeuchi,‡ Jinlong Zhang, Yu Horiuchi,‡ Masakazu Anpo,‡ and Detlef W. Bahnemann*,† †Institut fur Technische Chemie, Leibniz Universitaẗ Hannover, Callinstrasse 3, D-30167 Hannover, Germany ‡Faculty of Engineering, Osaka Prefecture University, 1 Gakuen-cho, Sakai Osaka 599-8531, Japan Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, China

Understanding TiO2 photocatalysis: mechanisms and materials.

Photoinduced reactivity of titanium dioxide

Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO2) semiconductor materials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applications. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 structure, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed. Emphasis is given to the origin of visible light absorption and the reactive oxygen species generated, deduced by physicochemical and photoelectrochemical methods. Various applications of VLA TiO2, in terms of environmental remediation and in particular water treatment, disinfection and air purification, are illustrated. Comprehensive studies on the photocatalytic degradation of contaminants of emerging concern, including endocrine disrupting compounds, pharmaceuticals, pesticides, cyanotoxins and volatile organic compounds, with VLA TiO2 are discussed and compared to conventional UV-activated TiO2 nanomaterials. Recent advances in bacterial disinfection using VLA TiO2 are also reviewed. Issues concerning test protocols for real visible light activity and photocatalytic efficiencies with different light sources have been highlighted.

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A review on the visible light active titanium dioxide photocatalysts for environmental applications

Human skin is a remarkable organ. It consists of an integrated, stretchable network of sensors that relay information about tactile and thermal stimuli to the brain, allowing us to maneuver within our environment safely and effectively. Interest in large-area networks of electronic devices inspired by human skin is motivated by the promise of creating autonomous intelligent robots and biomimetic prosthetics, among other applications. The development of electronic networks comprised of flexible, stretchable, and robust devices that are compatible with large-area implementation and integrated with multiple functionalities is a testament to the progress in developing an electronic skin (e-skin) akin to human skin. E-skins are already capable of providing augmented performance over their organic counterpart, both in superior spatial resolution and thermal sensitivity. They could be further improved through the incorporation of additional functionalities (e.g., chemical and biological sensing) and desired properties (e.g., biodegradability and self-powering). Continued rapid progress in this area is promising for the development of a fully integrated e-skin in the near future.

25th Anniversary Article: The Evolution of Electronic Skin (E-Skin): A Brief History, Design Considerations, and Recent Progress

In this work, we report the synthesis of fragmented lignin (FL) assisted zinc oxide (ZnO) and titanium oxide (TiO2) nanocomposites. The fragmented lignin synthesized from biomass (sugarcane bagasse) was used as a template to generate the morphology and crystallite structure of metal oxide nanomaterial. The nanocomposites were synthesized by a simple precipitation method, wherein fragmented lignin is used in alkaline medium as a template. X-ray diffraction (XRD) analysis shows the phase formation of hexagonal wurtzite ZnO and mixed phase formation of TiO2 as rutile and anatase. The morphology was studied by using field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM). The FE-SEM of pristine ZnO nanocomposites showed a cluster of particles whereas FL–ZnO NPs showed self-aligned nanoparticles in the form of rod shaped having average size 30–70 nm. Pristine TiO2 nanoparticles showed clusters of particles and FL–TiO2 nanocomposites showed well crystalline 41nm size nanocomposites. The FL acts as a surfactant which restrict the cluster formations. The band gap determined by diffuse reflectance spectra is 3.10 eV and 3.20 eV for FL–ZnO and FL–TiO2 nanocomposites, respectively. Photoluminescence spectra of both nanocomposites showed structural defects in the visible region. Further, the antimicrobial activity of pristine ZnO and TiO2 nanoparticles, and FL–ZnO and FL–TiO2 nanocomposites against Escherichia coli (ATCC25922), Staphylococcus aureus (ATCC25923) were studied under UV-A (315-400 nm) (8W) for 30min.

https://www.mdpi.com/2504-477X/3/3/90/pdf

Lignin-Mediated Biosynthesis of ZnO and TiO2 Nanocomposites for Enhanced Antimicrobial Activity

Exploring the impact of sintering additives on the densification and conductivity of BaCe0.3Zr0.55Y0.15O3-δ electrolyte for protonic ceramic fuel cells

Herein, a facile hydrothermally-assisted sonochemical approach for the synthesis of a ZnO decorated Sn3O4 nano-heterostructure is reported. The phase purity of the nano-heterostructure was confirmed by X-ray diffraction and Raman spectroscopy. The morphological analysis demonstrated a nanosheet-like structure of Sn3O4 with a thickness of 20 nm, decorated with ZnO. The optical band gap was found to be 2.60 eV for the ZnO@Sn3O4 nano-heterostructure. Photoluminescence studies revealed the suppression of electron–hole recombination in the ZnO@Sn3O4 nano-heterostructure. The potential efficiency of ZnO@Sn3O4 was further evaluated towards photocatalytic hydrogen production via H2O splitting and degradation of methylene blue (MB) dye. Interestingly, it showed significantly superior photocatalytic activity compared to ZnO and Sn3O4. The complete degradation of MB dye solution was achieved within 40 min. The nano-heterostructure also exhibited enhanced photocatalytic activity towards hydrogen evolution (98.2 μmol h−1/0.1 g) via water splitting under natural sunlight. The superior photocatalytic activity of ZnO@Sn3O4 was attributed to vacancy defects created due to its nano-heterostructure.

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ZnO decorated Sn3O4 nanosheet nano-heterostructure: a stable photocatalyst for water splitting and dye degradation under natural sunlight

Flower-like nanostructures of molybdenum disulphide (MoS2) have been effectively synthesised by the hydrothermal method and further doped with nitrogen using varying concentrations of urea. The formed hierarchical nanostructures are characterised by spectroscopy as well as electrochemical techniques. The structural analysis confirms the formation of a hexagonal MoS2 crystal structure. The existence of MoO2/MoO3/MoS2 composites is also observed after heating MoS2 with a lower urea concentration. Surface morphological analysis of all the prepared compositions shows the appearance of flower-like nanostructures formed by the stacking of 20–80 nanosheets to create individual flower petals. Nitrogen doping shows enhancement in the specific capacitance of MoS2 due to an increase in the electronic conductivity. Furthermore, the specific capacitance is enhanced due to the formation of an MoO2/MoO3/MoS2 composite. The highest specific capacitance calculated from the charge–discharge curve for nitrogen-doped MoS2 prepared using 1 : 1 (MoS2 : urea) weight ratio is observed at around 129 (F g−1) at 2 (A g−1) specific current. The nitrogen-doped MoS2 demonstrates almost four-fold enhancement in specific capacitance than pristine nano-shaped MoS2.

/pdf/hierarchical-nanostructures-of-nitrogen-doped-molybdenum-44baa5uxif.pdf

Bharat B. Kale

Papers

Lignin-Mediated Biosynthesis of ZnO and TiO2 Nanocomposites for Enhanced Antimicrobial Activity

Exploring the impact of sintering additives on the densification and conductivity of BaCe0.3Zr0.55Y0.15O3-δ electrolyte for protonic ceramic fuel cells

ZnO decorated Sn3O4 nanosheet nano-heterostructure: a stable photocatalyst for water splitting and dye degradation under natural sunlight

Hierarchical nanostructures of nitrogen-doped molybdenum sulphide for supercapacitors

Removal of OH impurities from GeS2 by reactive atmosphere and its glass preparation