Structure, Optical Properties, and Photocatalytic Activity towards H 2

High quality single crystalline GaN nanowires with large aspect ratio (>100) are synthesized on n-type Si (111) substrate via Au-catalyzed vapor-liquid-solid process. Morphology, crystal structure, and optical property of the as-synthesized GaN nanowires are characterized by means of X-ray diffraction, scanning/transmission electron microscopy, UV-vis diffuse reflection spectroscopy, and room temperature photoluminescence. The results indicate that the as-prepared GaN nanowires with a large aspect ratio are well crystallized in the hexagonal wurtzite structure, and a slight blue shift appears in both the absorption edge and emission peak probably due to the quantization effect. Photocatalytic H2 evolution over the as-prepared GaN nanowires is performed with the incorporation of Pt or Rh as the cocatalyst, exhibiting greatly enhanced capability compared to the GaN powder tested under the same conditions. Moreover, photocatalytic CO2 reduction over the GaN nanowires is also successfully realized using Pt or Rh as the cocatalyst, depending on which the products show a strong selectivity inherently related to the reductive electrons transferred by cocatalyst

Multiple telecouplings and their complex interrelationships

Increasingly, the world is becoming socioeconomically and environmentally connected, but many studies have focused on human-environment interactions within a particular area. Although some studies have considered the impacts of external factors, there is little research on multiple reciprocal socioeconomic and environmental interactions between a focal area and other areas. Here we address this important kowledge gap by applying the new integrated framework of telecouplings (socioeconomic and environmental interactions between two or more areas over distances). Results show that even a protected area - i.e., the Wolong Nature Reserve for giant pandas in southwest China - has multiple telecoupling processes with the rest of the world; these include panda loans, tourism, information dissemination, conservation subsidies, and trade of aricultural and industrial products. The telecoupling processes exhibit nonlinear patterns, they change over time, and they have varying socioeconomic and environmental effects across the world. We also find complex relationships among different telecouplings - e.g., amplification, offsetting, spatial overlaps - which cannot be detected by traditional separate studies. Such an integrated study leads to a more comprehensive understanding of distant human-enviroment interactions and has significant implications for global sustainability and human well-being

A survey on heterogeneous face recognition: Sketch, infra-red, 3D and low-resolution

Heterogeneous face recognition (HFR) refers to matching face imagery across different domains. It has received much interest from the research community as a result of its profound implications in law enforcement. A wide variety of new invariant features, cross-modality matching models and heterogeneous datasets are being established in recent years. This survey provides a comprehensive review of established techniques and recent developments in HFR. Moreover, we offer a detailed account of datasets and benchmarks commonly used for evaluation. We finish by assessing the state of the field and discussing promising directions for future research

The Effects of Crystal Structure and Electronic Structure on Photocatalytic H2 Evolution and CO2 Reduction over Two Phases of Perovskite-Structured NaNbO3

Cubic and orthorhombic NaNbO3 were fabricated to study the effects of crystal structure and electronic structure on the photocatalytic activities in detail. The samples were characterized by X-ray diffraction, field emission transmission electron microscopy, high-resolution transmission electron microscopy, UV-visible absorption spectroscopy, and X-ray photo-electron spectroscopy. The photocatalytic activities of the two phases of NaNbO3 have been assessed by H2 evolution from aqueous methanol solution and CO2 photoreduction in gas phase. The photocatalytic H2 evolution and CO2 reduction activities over cubic NaNbO3 were nearly twice of those over orthorhombic NaNbO3. The first-principles calculation reveals that the higher activity over cubic NaNbO3 can be attributed to its unique electronic structure, which is beneficial for electron excitation and transfer

Photocatalytic Degradation of Isopropanol Over PbSnO₃Nanostructures Under Visible Light Irradiation

Abstract Nanostructured PbSnO3photocatalysts with particulate and tubular morphologies have been synthesized from a simple hydrothermal process. As-prepared samples were characterized by X-ray diffraction, Brunauer&#8211;Emmet&#8211;Teller surface area, transmission electron microscopy, and diffraction spectroscopy. The photoactivities of the PbSnO3nanostructures for isopropanol (IPA) degradation under visible light irradiation were investigated systematically, and the results revealed that these nanostructures show much higher photocatalytic properties than bulk PbSnO3material. The possible growth mechanism of tubular PbSnO3catalyst was also investigated briefly.</p

Combustion process for magnetic copper–cobalt ferrite and its Congo red adsorption property

A rapid combustion process was introduced for the preparation of magnetic copper–cobalt ferrite, which was characterized using X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Brunauer–Emmett–Teller techniques (BET). The prepared magnetic copper–cobalt ferrite showed a large specific surface area (104.6 cm ^2 g ^−1 ) and nanoscale particle size (55.4 nm), with a saturation magnetization of 19.6 Am ^2 kg ^−1 . The nanoparticles were used to adsorb and remove Congo red (CR) from dyestuff wastewater, and the adsorption mechanism was revealed. Compared with the pseudo-first-order kinetic model and intraparticle diffusion kinetic model, the pseudo-second-order kinetic model was better at describing the CR adsorption process on the Cu _0.5 Co _0.5 Fe _2 O _4 nanoparticles, while the Temkin isotherm best fitted the CR adherence on the Cu _0.5 Co _0.5 Fe _2 O _4 nanoparticles. All data suggested that the adsorption of CR on the Cu _0.5 Co _0.5 Fe _2 O _4 nanoparticles followed the mono-multilayer hybrid chemisorption mechanism. In addition, as the pH increased from 2 to 10, the adsorption capacity of the Cu _0.5 Co _0.5 Fe _2 O _4 nanoparticles for CR decreased, indicating that an acidic environment was beneficial for the adsorption of CR on the Cu _0.5 Co _0.5 Fe _2 O _4 nanoparticles. When recycling the Cu _0.5 Co _0.5 Fe _2 O _4 nanoparticles after adsorbing CR, the relative adsorption rate was still 62.5% of the initial adsorption capacity after five cycles, revealing the reusability and promising applicability of Cu _0.5 Co _0.5 Fe _2 O _4 nanoparticles in sewage treatment

Preface for Special Topic: Photocatalysis

[no abstract available

Correlation of crystal structures, electronic structures, and photocatalytic properties in a series of Ag-based oxides: AgAlO2, AgCrO2, and Ag2CrO4

Three Ag-based oxides, AgAlO2, AgCrO2, and Ag2CrO4, were prepared by the cation exchange method. Powder X-ray diffraction analysis showed that AgAlO2 and Ag2CrO4 crystallized in orthorhombic structures and AgCrO2 crystallized in a hexagonal structure. The band gaps of AgAlO2, AgCrO2, and Ag2CrO4 were estimated to be 2.95, 1.68, and 1.75 eV, respectively. The photooxidation of Methyl Orange and gaseous benzene were performed to test the activities of the three materials. In the two kinds of reactions, the activity orders were both Ag2CrO4 &gt; AgAlO2 &gt; AgCrO2, and it was found that the novel photocatalyst, Ag2CrO4, showed activity in the visible region up to 570 nm. The correlation among crystal structures, electronic structures, and photocatalytic properties in the three Ag-based oxides is discussed in detail