Bi₂WO₆ Quantum Dots Decorated Reduced Graphene Oxide: Improved Charge Separation and Enhanced Photoconversion Efficiency

In this study, Bi₂WO₆ quantum dots (QDs) decorating reduced graphene oxide (RGO) sheets were produced by a facile one-step hydrothermal synthesis process, which converts the reactant precursors to Bi₂WO₆ QDs and RGO simultaneously. The Bi₂WO₆ QDs with a size of 3–5 nm anchored uniformly on the RGO sheets to form RGO-Bi₂WO₆ QDs composites. The RGO sheets not only acted as a supporter and stabilizer for the Bi₂WO₆ QDs to prevent them from being aggregation but also largely improved the charge separation in the composite material. For this preponderance, the electron lifetime in the RGO-Bi₂WO₆ QDs composites was increased 8-fold compared with that of the pure Bi₂WO₆ QDs. The much enhanced lifetime improved its performance in environmental purification and photovoltaic conversion under the irradiation of simulated sun light. This work not only provides a principle method to produce graphene-composited multiple metal oxide QDs by one-step process but also a route to obtain efficient functional material for environmental purification and optoelectronic applications

Efficient Contaminant Removal by Bi₂WO₆ Films with Nanoleaflike Structures through a Photoelectrocatalytic Process

Bi₂WO₆ films with nanoleaflike structures, which are directly grown on a fluorinated tin oxide substrate, were first realized by a solvothermal method. Because of the peculiar leaflike structure, Bi₂WO₆ films exhibited excellent photocatalytic activity in the degradation of phenol, which is widely used but slowly degradable in the natural environment. The degradation of phenol could be further improved by a photoelectrocatalytic process, along with a sharp decrease of total organic carbon. According to the experimental results, a possible mechanism of the improved photoelectrocatalytic activity on the phenol removal was proposed. The stability of the directly grown leaflike Bi₂WO₆ film is excellent. As an immobilized film, it is easy to recycle for the next photoelectrocatalytic process. This advantage, combining the excellent stability and photoelectrocatalytic activity, makes it applicable in practical environmental purification

Internal Electric Field Assisted Photocatalytic Generation of Hydrogen Peroxide over BiOCl with HCOOH

Hydrogen peroxide (H₂O₂) is a superb, clean, and versatile reagent. However, large-scale production of H₂O₂ is manufactured through nongreen methods that motivate people to develop more efficient and green technologies as alternatives. As a novel and green technology used for H₂O₂ generation, the efficiency of photocatalysis is still far from satisfactory. Here, we demonstrate a novel and efficient path of the generation of H₂O₂ in BiOCl photocatalysis but not the direct electron reduction of O₂ or hole oxidation of OH^– to H₂O₂. Super high production (685 μmol/h) of H₂O₂ by the addition of HCOOH as the hole shuttle was realized over BiOCl nanoplates. In this photocatalytic system, the BiOCl supplied abundant photoinduced holes to initiate HCOO^• radical. The HCOO^• further reacts with OH^– to •OH which is proven to be the source of the H₂O₂. Apart from HCOOH, O₂ also played important roles. The O₂ not only promoted the reaction through the cycle between Bi³⁺ and Bi, which decreased the combination of carriers, but also avoided the carbonation of surfaces, thus achieving the high production of H₂O₂ (1020 μmol/h). In this work, we shed light on a deep understanding of the photocatalytic evolution of H₂O₂ in a novel perspective and achieve high production

Descriptive statistics and correlations of the severity of PTSD, anxiety and depression symptoms.

*<p>P<0.05,</p>**<p>P<0.01; the parentheses include the number of items in each scale or subscale.</p

Bivariate logistic regression analyses of the effects of demographics, trauma exposure and social support on the odds of probable PTSD, anxiety and depression.

<p>OR = odds ratio; CIs = confidence intervals.</p>*<p>P<0.05,</p>**<p>P<0.01.</p>#<p>Numbers within categories may not add up to 505 for some variables due to missing data.</p

Insights into the Surface-Defect Dependence of Photoreactivity over CeO₂ Nanocrystals with Well-Defined Crystal Facets

Crystal facet engineering (CFE) has been widely employed to regulate the photoreactivity of crystalline materials, mostly concerning the surface atomic and electronic structures. However, surface defects ubiquitous in real catalysts have long been less recognized. An integrated examination of various influence factors is necessary for the elucidation of an accurate structure–function relationship. Herein, we carefully studied the heterogeneous photoreactivity of CeO₂ nanocrystals (NCs) with well-defined crystal facets in multiple processes, including photocatalytic oxidation of volatile organic compounds (VOCs), O₂ evolution, and ·OH generation. Variable reactivity priorities were found between different nanoshapes as well as samples of identical nanoshapes. With integrated examinations of the coexisting surface factors (i.e., atomic, electronic, and defect structures), surface defects were evidently proved to compete with other surface factors in deciding the final photoreactivity orders. Surface-defect structure (e.g., Ce³⁺ ions and O vacancies) was suggested to greatly influence the surface properties of ceria NCs, including the activation of reactants as well as the mobility of surface lattice oxygen. The results clearly confirm the surface-defect dependence of photoreactivity and provide further insights into the complex surface effects in semiconductor photocatalysis. It also underscores the significance of surface-defect structure as an essential supplement to the traditional CFE strategy for achieving desired solar energy utilization

Participant demographic information (n = 505).

<p>Participant demographic information (n = 505).</p

Multivariate logistic regression analyses of the factors significantly associated with PTSD, anxiety and depression.

<p>All significant univariate logistic analysis variables (i.e., P-values equal to 0.05 or less) were included in the multivariate logistic regression.</p

Bismuth-Induced Integration of Solar Energy Conversion with Synergistic Low-Temperature Catalysis in Ce_1–<i>x</i>Bi_<i>x</i>O_2−δ Nanorods

For conventional photocatalysis, the energy threshold rather than merely the spectral response is always restricted that the infrared part (48% of solar energy) has never been efficiently utilized, undesirably elevating the temperature and damaging the photon-to-electron conversion. It remains challenging to conquer the IR-related contradiction and integrate the infrared energy into the solar energy conversion. Herein, we logically designed a Bi-induced synergistic photo/thermocatalyst (fluorite Ce_1–<i>x</i>Bi_<i>x</i>O_2−δ nanorods), where the coupled ionic conductivity accompanying highly reductive Bi and concomitant oxygen vacancies helped bring about integration of photocatalysis with synergistic low temperature (20–80 °C, IR-driven) catalysis, promising for the effective utilization of infrared energy. More generally, through our results a feasible methodology is verified in detail that integration of semiconductor photocatalysis with solid state ionics may help design brand new catalysts, shedding light on the practical solar energy conversion

Equilibrating the Plasmonic and Catalytic Roles of Metallic Nanostructures in Photocatalytic Oxidation over Au-Modified CeO₂

Finite amounts of noble metals have been widely introduced as surface plasmon resonance (SPR) mediators and reductive cocatalysts for solar-driven energy conversion. At present, knowledge of the roles of metal loading is multifarious and may be one-sided in some cases. In addition, the catalytic roles which metals play in photocatalytic oxidation have been rarely discussed. It is necessary to explore the equilibrium between plasmon resonance and surface catalysis over metallic nanostructures. Herein, Au NPs with various loading amounts (0.25–1 wt %) and particle sizes (3–20 nm) were attached to CeO₂ by photodeposition. Aerobic oxidations of propylene under simulated sunlight and visible (>420 nm) light irradiation were selected as probe reactions. Both processes exhibited similar humplike activity dependence upon Au NP addition, with a peak at 0.67 wt % loading and a size of 8.4 nm. Modifications to the whole photocatalytic process brought by metal attachment have been integrally examined, concerning both the photoexcitation and surface catalysis steps. With an increase of Au loading, the induced SPR photoabsorption, charge separation, and resonant energy transfer were enhanced, whereas outgrown Au NPs (>10 nm) led to the saturation of exposed active sites for reactant adsorption as well as distinct passivity to O₂ dissociation. Therefore, photoexcitation and surface catalysis present opposite dependence on Au NP size and codetermine the final photocatalytic performance in propylene oxidation. An integral consideration of the above two aspects should be instructive for a better understanding of SPR-enhanced photocatalysis and the design of efficient metal–semiconductor systems for ideal solar energy conversion