Architecting Nitrogen Functionalities on Graphene Oxide Photocatalysts for Boosting Hydrogen Production in Water Decomposition Process

This study elucidates how nitrogen functionalities influence the transition and transfer of photogenerated electrons in graphene‐based materials. Graphene oxide dots (GODs) and Nitrogen‐doped GODs (NGODs) are synthesized by thermally treating graphene oxide (GO) sheets in argon and ammonia, respectively, and then ultrasonically exfoliating the sheets in nitric acid. The nitrogen functionalities of NGODs are mainly quaternary/pyridinic/pyrrolic, and the nitrogen atoms in these functionalities are planar to the GO sheets and repair the vacancy defects on the sheets. Hydrothermal treatment of NGODs in ammonia yields ammonia‐treated NGODs (A‐NGODs), with some pyridinic/pyrrolic groups being converted to amino/amide groups. The nitrogen atoms in the amino/amide groups are not planar to the GO sheets and are prone to donate their lone pair electrons to resonantly conjugate with the aromatic π electrons. The promoted conjugation facilitates the relaxation of photogenerated electrons to the triplet states and prolongs the electron lifetime. When deposited with Pt as the co‐catalyst, the samples catalyze H₂ production from an aqueous triethanolamine solution under 420 nm monochromatic irradiation at quantum yields of 7.3% (GODs), 9.7% (NGODs), and 21% (A‐NGODs). The high activity of A‐NGODs demonstrates that architecting nitrogen functionalities effectively mediate charge motion in carbon‐based materials for application to photoenergy conversion.     

Operando Oxygen Vacancies for Enhanced Activity and Stability toward Nitrogen Photofixation

Photocatalysts with oxygen vacancies (OVs) have exhibited exciting activity in N₂ photofixation due to their superiority in capture and activation of N₂. However, the surface OVs are easily oxidized by seizing the oxygen atoms from water or oxygen during the catalytic reaction. Here, it is reported that the grain boundaries (GBs) in nanoporous WO₃ induce plenty of operando OVs under light irradiation to significantly boost catalytic activity toward N₂ photofixation. Impressively, nanoporous WO₃ with abundant GBs (WO₃‐600) exhibit an ammonia production rate of 230 µmol g_cat.^?1 h^?1 without any sacrificial agents at room temperature, 17 times higher than that for WO₃ nanoparticles without GBs. Moreover, WO₃‐600 also manifests remarkable stability by maintaining nearly ≈100% catalytic activity after ten successive reaction rounds. Further mechanistic studies reveal that both OVs and GBs regulate the band structures of WO₃ nanocrystals, as well as favor the delivery of photogenerated electrons to adsorbed N₂ by enhancing W–O covalency. More importantly, plenty of operando OVs induced by GBs generate during catalytic reaction, directly contributing to the excellent catalytic performance for WO₃‐600. This work opens a novel avenue to developing efficient photocatalysts by construction of operando OVs.     

Enhancement of the biodegradability of model wastewater containing recalcitrant or inhibitory chemical compounds by photocatalytic pre-oxidation

m-Dinitrobenzene, diphenylamine and resorcinol, threearomatic compounds found inhibitory or recalcitrant tobiological treatments, were chosen as model chemicalsfor this study on the integration ofphotocatalytic-biological treatments. The degradationof each of these compounds was achieved by ultravioletphotocatalytic oxidation, leading to the formation ofintermediate compounds. The photocatalytic treatmentwas performed in a TiO₂ slurry reactor containingan aqueous solution of one of the three chemicals. Thebiodegradability of model wastewater treatedphotocatalytically was measured in terms ofBOD₁/TOC. Intermediate compounds that appeared atearly stages of the photocatalytic degradation ofm-dinitrobenzene or diphenylamine seemed to be moreinhibitory than the parent compounds but this was notthe case for resorcinol. A substantial improvement inBOD₁/TOC could be achieved, but it required themineralization of at least 80% of the organic carbonoriginally in the water. Microtox® toxicityresults confirmed the BOD₁/TOC trends fordiphenylamine.     

Photocatalytic disinfection of Giardia intestinalis and Acanthamoeba castellani cysts in water

In this study, disinfection of water containing Giardia intestinalis and Acanthamoeba castellani cysts with TiO2 and modified catalyst silver loaded TiO2 (Ag-TiO2) was investigated. Destruction of the parasites was evaluated after UV illumination of the suspension consisting 5 x 10(8)-13.5 x 10(8)cysts/mL in the presence of 2g/L neat or modified TiO2 at neutral pH. In the initial stage, the solid photocatalyst particles penetrated the cyst wall and then oxidant species produced by TiO2/UV destroyed both cell wall and intracellular structure. In the case of G. intestinalis inactivation (disinfection) performance of TiO2/UV system reached 52.5% only after 25 min illumination and total parasite disinfection was achieved after 30 min illumination. However, silver loaded TiO2 seemed to be more effective as this loading provided better catalytic action as well as additional antimicrobial properties. Cell viability tests showed that parasite cysts, their walls in particular, were irreversibly damaged and cysts did not re-grow. Nevertheless the studied system seemed to be ineffective for the inactivation of A. castellani. Inactivation percentages of TiO2/UV and Ag-TiO2/UV systems were far lower than that of UV alone, being 50.1% and 46.1%, respectively.     

新疆沙雅县土地利用规划战略环境评价

随着全国性、地区性土地利用规划的制定与实施,探讨适合于土地利用总体规划环境影响评价的技术方法具有重要意义.采用战略环境评价理论,以生态系统服务价值为评价指标,对新疆沙雅县1996—2010年土地利用规划可能带来的生态环境影响进行了综合评价.结果表明：1996—2010年间,沙雅县生态系统服务价值从1996年的69.33×10⁸元增加到2010年的70.81×10⁸元,其年增长率为0.15%.规划期间,研究区土地利用变化导致的生态系统服务价值变化呈增加趋势,表明该规划基本合理,但需要加强对社会用地等方面的控制;该区生态价值的增长速率高于其GDP的增长速率,属于生态价值盈利地区,但该规划还存在一些不足,如未利用地（荒漠）面积的比例到2010年将达到83.95%,故应对此规划进行完善和修改,以提高土地利用的生态效益.     

Solar‐to‐Hydrogen Energy Conversion Based on Water Splitting

Artificial photosynthesis provides a blueprint to harvest solar energy to sustain the future energy demands. Solar‐driven water splitting, converting solar energy into hydrogen energy, is the prototype of photosynthesis. Various systems have been designed and evaluated to understand the reaction pathways and/or to meet the requirements of potential applications. In solar‐to‐hydrogen conversion, electrocatalytic hydrogen and oxygen evolution reactions are key research areas that are meaningful both theoretically and practically. To utilize hydrogen energy, fuel cell technology has been extensively investigated because of its high efficiency in releasing chemical energy. In this review, general concepts of the photosynthesis in green plants are discussed, different strategies for the light‐driven water splitting proposed in laboratories are introduced, the progress of electrocatalytic hydrogen and oxygen evolution reactions are reviewed, and finally, the reactions in hydrogen fuel cells are briefly discussed. Overall, the mass and energy circulation in the solar‐hydrogen‐electricity circle are delineated. The authors conclude that attention from scientists and engineers of relevant research areas is still highly needed to eliminate the wide disparity between the aspirations and realities of artificial photosynthesis.     

Au/TiO2–gC3N4 Nanocomposites for Enhanced Photocatalytic H2 Production from Water under Visible Light Irradiation with Very Low Quantities of Sacrificial Agents

Here for the first time the design and optimization are presented of a three‐component Au/TiO₂–gC₃N₄ nanocomposite photocatalyst able to efficiently produce H₂ from water using very low amounts of sacrificial agents and under visible light irradiation. This enhanced photocatalytic behavior compared to Au/TiO₂ and Au/gC₃N₄ materials is the result of synergetic effects due to high quality assembly and interface between the three components. This optimized nanoscale assembly characterized by simultaneous favorable nanoheterojunction formation between g‐C₃N₄ and TiO₂ semiconductors, as well as AuNPs/gC₃N₄ and AuNPs/TiO₂ junctions, leads to enhanced visible light harvesting, charge separation, and H₂ production. This composite photocatalyst yields a high H₂ production (350 µmol^?1 h^?1 g_catalyst^?1) under visible light irradiation with minimal amounts of sacrificial agent (≤1 vol%), corresponding to activities much higher than reported so far under comparable conditions.     

Preparation of S-(+)-ketoprofen by coupling the enantioselective hydrolysis of ketoprofen methyl ester with the photo-oxidation of methanol

A novel method for preparation of S-(+)-ketoprofen is presented involving coupling enantioselective hydrolysis of ketoprofen methyl ester catalyzed by a surfactant-coated-lipase with the photo-oxidation of methanol in a water-saturated organic solvent. The effect of photocatalytic conversion of methanol into water and carbon dioxide on the hydrolysis of ketoprofen methyl ester and the stability of the enzyme was investigated. The photo-oxidation of methanol shifted the equilibrium of the hydrolysis toward the formation of ketoprofen, increasing the equilibrium conversion ratio and improving the enantioselectivity. Because the surfactant-coated lipase and ketoprofen methyl ester dissolved in the organic solvent and ketoprofen was absorbed on the TiO₂ photocatalyst particles, the separation procedures could be simplified and the stability of the enzyme was increased.     

Antifouling properties of zinc oxide nanorod coatings

In laboratory experiments, the antifouling (AF) properties of zinc oxide (ZnO) nanorod coatings were investigated using the marine bacterium Acinetobacter sp. AZ4C, larvae of the bryozoan Bugula neritina and the microalga Tetraselmis sp. ZnO nanorod coatings were fabricated on microscope glass substrata by a simple hydrothermal technique using two different molar concentrations (5 and 10?mM) of zinc precursors. These coatings were tested for 5?h under artificial sunlight (1060?W?m^?2 or 530?W?m^?2) and in the dark (no irradiation). In the presence of light, both the ZnO nanorod coatings significantly reduced the density of Acinetobacter sp. AZ4C and Tetraselmis sp. in comparison to the control (microscope glass substratum without a ZnO coating). High mortality and low settlement of B. neritina larvae was observed on ZnO nanorod coatings subjected to light irradiation. In darkness, neither mortality nor enhanced settlement of larvae was observed. Larvae of B. neritina were not affected by Zn²⁺ ions. The AF effect of the ZnO nanorod coatings was thus attributed to the reactive oxygen species (ROS) produced by photocatalysis. It was concluded that ZnO nanorod coatings effectively prevented marine micro and macrofouling in static conditions.