By using an alternative wet-etch procedure, we have obtained high-quality atomically flat TiO2 terminated surfaces of SrTiO3 single crystals with the morphology equivalent to that of the conventional wet-etch methods. By applying a combined power of photoluminescence (PL) spectroscopy, reflection high-energy electron diffraction, atomic force microscopy imaging, and soft x-ray absorption (XAS), we were able to identify and monitor the complex evolution of oxygen defect states and Ti valency at the surface and near-surface layers. Our experiments revealed a high level of local defects resulting in the presence of the Ti3+ states at the surface. We have developed a method to control the defect states capable of a marked reduction of the defect concentration. We have demonstrated that the PL and XAS are able to distinguish the surface-related Ti3+ states from oxygen vacancies trapping charge transfer vibronic excitons that define the PL intensity. The experimental findings will have important implications for the growth of high-quality ultrathin complex oxide heterostructures.

13A new synthesis method was developed to produce Zinc-biochar nanocomposites 14 from sugarcane bagasse. The modified biochar maintained 1.2 to 2.0 times higher 15 removal efficiency than that of pristine biochar. FTIR, XPS, BET and SEM were used 16 to analysis the physical and chemical properties of the composite adsorbent. Batch 17 sorption experiments were carried out to investigate the adsorption behavior of Cr(VI) 18 by Zinc-biochar. Experimental data were better fitted by pseudo-second-order kinetics 19 equation and Freundlich isotherms model. Thermodynamic analysis indicated that the 20 adsorption process was spontaneous and endothermic. The maximum adsorption of 21 the modified biochar was observed at pH 2.0 with the sorption capacity of 102.66 mg 22 g -1 . The adsorbed Zinc-biochar could be effectively regenerated by 0.5 mol L -1 NaOH 23 solutions and the adsorption ability decreased from 84.16 to 59.75 mg g -1 in the sixth 24 cycles. In conclusion, the porous Zinc-biochar showed great potential advantages in 25 the removal of Cr(VI) from wastewater.26

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Heavy metal pollution is a major concern of the public due to their threats to the safety of food chains. A 60-day pot experiment was conducted using Macleaya cordata as plant material to investigate the phytoremediation potential and anti-oxidative responses of M. cordata under different Cd stress. Significant growth inhibition phenomenon and toxic symptoms were not detected in the experiment. The high biomass of the plant provided high accumulation capacity for Cd with an average dry weight of 3.6 g. The maximum extraction amount of Cd was 393 μg·plant(-1), suggesting that this species had potential for phytoremediation of Cd-contaminated soil. A slight increase of chlorophyll (CHL) content was observed in Cd10 treatment. The plant was confirmed to have relatively high tolerance to the Cd stress on the basis of tolerance indexes (TI), relative water content, and CHLa/CHLb ratio. M. cordata could maintain high level of superoxide dismutase (SOD) activity under Cd stress, indicating strong tolerance capacity for reactive oxygen species (ROS) in plant cells. Catalase (CAT) activity show a certain range of decline in the experiment compare to the control. And peroxidase (POD) activity in leaves changed irregularly when compared to the control. The malondialdehyde (MDA) content increased as Cd concentration elevated compared to the control. In addition, as an inedible crop with relatively high economic value, M. cordata have shown the advantage of high biomass and high tolerance under Cd stress, which can provide a new plant resource for sustainable phytoremediation.