Novel Ag-Bridged Z-Scheme CdS/Ag/Bi2WO6 Heterojunction: Excellent Photocatalytic Performance and Insight into the Underlying Mechanism.

The construction of semiconductor heterojunction photocatalysts that improve the separation and transfer of photoinduced charge carriers is an effective and widely employed strategy to boost photocatalytic performance. Herein, we have successfully constructed a CdS/Ag/Bi2WO6 Z-scheme heterojunction with an Ag-bridge as an effective charge transfer channel by a facile process. The heterostructure consists of both CdS and Ag nanoparticles anchored on the surface of Bi2WO6 nanosheets. The photocatalytic efficiency of the CdS/Ag/Bi2WO6 system was studied by the decontamination of tetracycline (TC) and Rhodamine B (RhB) under visible light irradiation (λ ≥ 420). The results exhibited that CdS/Ag/Bi2WO6 shows markedly higher photocatalytic performance than that of CdS, Bi2WO6, Ag/Bi2WO6, and CdS/Bi2WO6. The trapping experiment results verified that the •O2- and h+ radicals are the key active species. The results of photoluminescence spectral analysis and photocurrent responses indicated that the CdS/Ag/Bi2WO6 heterojunctions exhibit exceptional efficiency in separating and transferring photoinduced electron-hole pairs. Based on a series of characterization results, the boosted photocatalytic activity of the CdS/Ag/Bi2WO6 system is mostly due to the successful formation of the Ag-bridged Z-scheme heterojunction; these can not only inhibit the recombination rate of photoinduced charge carriers but also possess a splendid redox capacity. The work provides a way for designing a Z-scheme photocatalytic system based on Ag-bridged for boosting photocatalytic performance.

Exploration of ecological restoration of saline-alkali land based on NbS--Study on the salt resistance and desalination performance of three cash crops.

Soil salinization is one of the current global environmental problems. Current research on crops in saline-alkali land focuses on salt tolerance, but less on its ecological benefits. However, plants and the environment can interact and influence each other, which is the theory used to carry out Nature-based Solutions (NbS). Therefore, the research on crop plants with both ecological and economic benefits is novel and valuable work. Then three widely planted cash crops (Solanum melongena, Momordica charantia, Capsicum annuum) were selected for salt stress treatment (NaCl, 150mmol/L), some physiological indicators (chlorophyll, soluble protein, Proline (Pro), malondialdehyde (MDA)) of plant and the soil properties (electrical conductivity, pH, the soil salt content) were measured. The results showed that the salinity content of the three plant cultivation soils was significantly different (P<0.05) after the salt stress; all three crops had some desalination capacity, but Capsicum annuum had the strongest salt resistance and desalination capacity.

Rationally Designed Bi2M2O9 (M = Mo/W) Photocatalysts with Significantly Enhanced Photocatalytic Activity.

Novel Bi2W2O9 and Bi2Mo2O9 with irregular polyhedron structure were successfully synthesized by a hydrothermal method. Compared to ordinary Bi2WO6 and Bi2MoO6, the modified structure of Bi2W2O9 and Bi2Mo2O9 were observed, which led to an enhancement of photocatalytic performance. To investigate the possible mechanism of enhancing photocatalytic efficiency, the crystal structure, morphology, elemental composition, and optical properties of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9 were examined. UV-Vis diffuse reflectance spectroscopy revealed the visible-light absorption ability of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9. Photoluminescence (PL) and photocurrent indicated that Bi2W2O9 and Bi2Mo2O9 pose an enhanced ability of photogenerated electron-hole pairs separation. Radical trapping experiments revealed that photogenerated holes and superoxide radicals were the main active species. It can be conjectured that the promoted photocatalytic performance related to the modified structure, and a possible mechanism was discussed in detail.

Seasonal change in response of stomatal conductance to vapor pressure deficit and three phytohormones in three tree species.

Stomatal behavior under global climate change is a central topic of plant ecophysiological research. Vapor pressure deficit (VPD) and phytohormones can affect stomata of leaves which can affect gas exchange characteristics of plant. The role of VPD in regulating leaf gas exchange of three tree species was investigated in Jinan, China. Experiments were performed in June, August, and October. Levels of three phytohormones (GA3, IAA, ABA) in the leaves of the three trees were determined by high-performance liquid chromatography in three seasons. The responses of stomatal conductance (gs) to an increasing VPD in the leaves of the three trees had peak curves under different seasons, which differed from the prevailing response pattern of gs to VPD in most literature. The peak curve could be fitted with a Log-Normal Model (R2 = 0.838-0.995). The VPD/RH values of the corresponding maximum of gs (gs-max-VPD/RH) could be calculated by fitted models. The gs-max-RH could be affected by environmental conditions, because of positive correlation between gs-max-RH and the mean monthly temperature in 2010 (R2 > 0.81). Two typical stomatal models (the Leuning model and the optimal stomatal behavior model) were used to estimate gs values, but they poorly predicted gs in the three trees. The concentration of ABA was positively correlated to sensitivity in response of stomatal conductance to VPD in the leaves of the tree species during the different seasons.

Cooking fuel decision-making and family structure: a field study in China.

Household air pollution caused by solid fuel use for cooking is prevalent in rural China and generates various environmental and health problems. Various potential impact factors on cooking fuel decision such as income, education, modern energy, and infrastructure are examined. However, the role of family structures has been ignored. A survey on household energy consumption pattern interrelating socio-economic and demographic factors was conducted in ten villages in Northern China using stratified random sampling technique. The number of family member eating together influences households' cooking fuel decision-making significantly. The numbers of school-age children and family members under 6 and above 60 years old have no significant influence on the household's cooking fuel decision-making respectively. Compared with families with neither child nor the elderly, those with no child but at least an elderly member have 0.103 lower probability of choosing clean fuels as their primary cooking fuel. Hence, the elderly owns a heavyweight in the household fuel decision-making process in rural China, and the government should formulate policies more in line with the background of the times to deal with rural energy issues.

Double Z-scheme system of silver bromide@bismuth tungstate/tungsten trioxide ternary heterojunction with enhanced visible-light photocatalytic activity.

The ternary heterojunction of silver bromide@bismuth tungstate/tungsten trioxide (AgBr@Bi2WO6/WO3) was designed and synthesised by hydrothermal and deposition-precipitation approaches. The composites were characterised by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy (XPS). The photoabsorption range and bandgaps of the photocatalysts were analysed by ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). Compared with Bi2WO6/WO3 or AgBr alone, the AgBr@Bi2WO6/WO3 composites displayed higher visible-light photocatalytic performance for degrading rhodamine B (RhB). AgBr@Bi2WO6/WO3 with 40% AgBr concentration was optimum for photocatalytic activity. Radical-trapping experiments revealed that superoxide anion radicals (O2-) and holes (h+) were the active species during photocatalytic degradation and that O2- was the dominant active species. Therefore, the increased photocatalytic activity of AgBr@Bi2WO6/WO3 was attributed to the atypical double Z-scheme system, which effectively improved the transfer and separation of electron-hole pairs in ternary heterojunction structures.

In-situ synthesis of novel Z-scheme SnS(2)/BiOBr photocatalysts with superior photocatalytic efficiency under visible light.

In this study, a novel SnS2/BiOBr heterojunction photocatalyst was synthesized via a facile in-situ growth strategy. The heterojunction interface was formed by loading BiOBr nanosheets on the surface of ultrathin hexagonal SnS2 nanoplates. UV/Vis diffuse reflectance spectroscopy (DRS) indicated that SnS2/BiOBr composites possessed stronger visible-light absorption. The as-fabricated SnS2/BiOBr heterojunction nanoplates exhibited considerable improvement in terms of photocatalytic activity for the degradation of rhodamine B (RhB) under visible light irradiation as compared with BiOBr and SnS2. The enhanced photocatalytic activity was attributed to the closely contacted interface between BiOBr and SnS2, thereby resulting in faster transfer of the photoinduced electron-hole pairs through their interface, as shown by the results of photoluminescence spectroscopy (PL) and photocurrent measurements. Radical trapping experiments demonstrated that holes (h+) and superoxide anion radicals (O2-) were the main active species in the photocatalytic oxidation process. The mechanism of the excellent photocatalytic activity of SnS2/BiOBr heterojunction composite was also discussed.

Samarium and Nitrogen Co-Doped Bi2 WO6 Photocatalysts: Synergistic Effect of Sm(3+) /Sm(2+) Redox Centers and N-Doped Level for Enhancing Visible-Light Photocatalytic Activity.

Samarium and nitrogen co-doped Bi2 WO6 nanosheets were successfully synthesized by using a hydrothermal method. The crystal structures, morphology, elemental compositions, and optical properties of the prepared samples were investigated. The incorporation of samarium and nitrogen ions into Bi2 WO6 was proved by X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. UV/Vis diffuse reflectance spectroscopy indicated that the samarium and nitrogen co-doped Bi2 WO6 possessed strong visible-light absorption. Remarkably, the samarium and nitrogen co-doped Bi2 WO6 exhibited higher photocatalytic activity than single-doped and pure Bi2 WO6 under visible-light irradiation. Radical trapping experiments indicated that holes (h(+) ) and superoxide radicals ((.) O2 (-) ) were the main active species. The results of photoluminescence spectroscopy and photocurrent measurements demonstrated that the recombination rate of the photogenerated electrons and holes pairs was greatly depressed. The enhanced activity was attributed to the synergistic effect of the in-built Sm(3+) /Sm(2+) redox pair centers and the N-doped level. The mechanism of the excellent photocatalytic activity of Sm-N-Bi2 WO6 is also discussed.