Selective Extraction of Critical Metals from Spent Li-Ion Battery Cathode: Cation-Anion Coordination and Anti-Solvent Crystallization.

Owing to continuing global use of lithium-ion batteries (LIBs), in particular in electric vehicles (EVs), there is a need for sustainable recycling of spent LIBs. Deep eutectic solvents (DESs) are reported as "green solvents" for low-cost and sustainable recycling. However, the lack of understanding of the coordination mechanisms between DESs and transition metals (Ni, Mn and Co) and Li makes selective separation of transition metals with similar physicochemical properties practically difficult. Here, it is found that the transition metals and Li have a different stable coordination structure with the different anions in DES during leaching. Further, based on the different solubility of these coordination structures in anti-solvent (acetone), a leaching and separation process system is designed, which enables high selective recovery of transition metals and Li from spent cathode LiNi1/3Co1/3Mn1/3O2 (NCM111), with recovery of acetone. Recovery of spent LiCoO2 (LCO) cathode is also evidenced and a significant selective recovery for Co and Li is established, together with recovery and reuse of acetone and DES. It is concluded that the tuning of cation-anion coordination structure and anti-solvent crystallization are practical for selective recovery of critical metal resources in the spent LIBs recycling.

The effect of Ge doping concentration on the electrochemical performance of silicene anode for lithium-ion batteries: a first-principles study.

Two-dimensional materials have been considered as novel anode materials for LIBs because of their large surface area, small volume change, and low Li diffusion barrier. Among them, the two-dimensional material SixGey has many excellent properties as an anode. However, Ge is expensive and not suitable for mass production. Therefore, proper Ge doping is of great significance to improve performance and reduce cost. Herein, we systematically study the effect of Ge doping and its concentration on the structure and electrochemical performance of two-dimensional SixGey by density functional theory (DFT) calculations. The incorporation of low concentration Ge can improve the horizontal and vertical diffusion ability of Li atoms compared to silicene. However, excessive Ge will increase the horizontal diffusion energy barrier of Li and reduce the theoretical capacity, where Si6Ge2 has a relatively high theoretical capacity and a low diffusion energy barrier. In addition, fully lithiated 2D SixGey shows poor electrical conductivity and increasing Ge concentration seems to be effective in improving the electrical conductivity of the material. This study will provide significant theoretical guidance for the design and preparation of two-dimensional silicon-based materials.

A Review of Integrated Systems Based on Perovskite Solar Cells and Energy Storage Units: Fundamental, Progresses, Challenges, and Perspectives.

With the remarkable progress of photovoltaic technology, next-generation perovskite solar cells (PSCs) have drawn significant attention from both industry and academic community due to sustainable energy production. The single-junction-cell power conversion efficiency (PCE) of PSCs to date has reached up to 25.2%, which is competitive to that of commercial silicon-based solar cells. Currently, solar cells are considered as the individual devices for energy conversion, while a series connection with an energy storage device would largely undermine the energy utilization efficiency and peak power output of the entire system. For substantially addressing such critical issue, advanced technology based on photovoltaic energy conversion-storage integration appears as a promising strategy to achieve the goal. However, there are still great challenges in integrating and engineering between energy harvesting and storage devices. In this review, the state-of-the-art of representative integrated energy conversion-storage systems is initially summarized. The key parameters including configuration design and integration strategies are subsequently analyzed. According to recent progress, the efforts toward addressing the current challenges and critical issues are highlighted, with expectation of achieving practical integrated energy conversion-storage systems in the future.

Ordered Macro/Mesoporous TiO2 Hollow Microspheres with Highly Crystalline Thin Shells for High-Efficiency Photoconversion.

Well ordered, uniform 3D open macro/mesoporous TiO2 hollow microspheres with highly crystalline anatase thin shells have been successfully synthesized by a simple solvent evaporation-driven confined self-assembly method. The 3D open macro/mesoporous TiO2 hollow microspheres show high energy-conversion efficiency (up to 9.5%) and remarkable photocatalytic activity (with photodegradation of 100% for methylene blue in 12 min under UV light irradiation).

Mesoporous TiO2 Mesocrystals: Remarkable Defects-Induced Crystallite-Interface Reactivity and Their in Situ Conversion to Single Crystals.

Oriented self-assembly between inorganic nanocrystals and surfactants is emerging as a route for obtaining new mesocrystalline semiconductors. However, the actual synthesis of mesoporous semiconductor mesocrystals with abundant surface sites is extremely difficult, and the corresponding new physical and chemical properties arising from such an intrinsic porous mesocrystalline nature, which is of fundamental importance for designing high-efficiency nanostructured devices, have been rarely explored and poorly understood. Herein, we report a simple evaporation-driven oriented assembly method to grow unprecedented olive-shaped mesoporous TiO2 mesocrystals (FDU-19) self-organized by ultrathin flake-like anatase nanocrystals (∼8 nm in thickness). The mesoporous mesocrystals FDU-19 exhibit an ultrahigh surface area (∼189 m(2)/g), large internal pore volume (0.56 cm(3)/g), and abundant defects (oxygen vacancies or unsaturated Ti(3+) sites), inducing remarkable crystallite-interface reactivity. It is found that the mesocrystals FDU-19 can be easily fused in situ into mesoporous anatase single crystals (SC-FDU-19) by annealing in air. More significantly, by annealing in a vacuum (∼4.0 × 10(-5) Pa), the mesocrystals experience an abrupt three-dimensional to two-dimensional structural transformation to form ultrathin anatase single-crystal nanosheets (NS-FDU-19, ∼8 nm in thickness) dominated by nearly 90% exposed reactive (001) facets. The balance between attraction and electrostatic repulsion is proposed to determine the resulting geometry and dimensionality. Dye-sensitized solar cells based on FDU-19 and SC-FDU-19 samples show ultrahigh photoconversion efficiencies of up to 11.6% and 11.3%, respectively, which are largely attributed to their intrinsic single-crystal nature as well as high porosity. This work gives new understanding of physical and chemical properties of mesoporous semiconductor mesocrystals and opens up a new pathway for designing various single-crystal semiconductors with desired mesostructures for applications in catalysis, sensors, drug delivery, optical devices, etc.

Combined hydrolysis acidification and bio-contact oxidation system with air-lift tubes and activated carbon bioreactor for oilfield wastewater treatment.

This paper investigated the enhancement of the COD reduction of an oilfield wastewater treatment process by installing air-lift tubes and adding an activated carbon bioreactor (ACB) to form a combined hydrolysis acidification and bio-contact oxidation system with air-lift tubes (HA/air-lift BCO) and an ACB. Three heat-resistant bacterial strains were cultivated and subsequently applied in above pilot plant test. Installing air-lift tubes in aerobic tanks reduced the necessary air to water ratio from 20 to 5. Continuous operation of the HA/air-lift BCO system for 2 months with a hydraulic retention time of 36 h, a volumetric load of 0.14 kg COD/(m(3)d) (hydrolysis-acidification or anaerobic tank), and 0.06 kg COD/(m(3)d) (aerobic tanks) achieved an average reduction of COD by 60%, oil and grease by 62%, total suspended solids by 75%, and sulfides by 77%. With a COD load of 0.56 kg/(m(3)d), the average COD in the ACB effluent was 58 mg/L.

ORF4-protein deficient PCV2 mutants enhance virus-induced apoptosis and show differential expression of mRNAs in vitro.

Porcine circovirus type 2 (PCV2) is the essential infectious agent of PCV associated disease (PCVAD). During previous in vitro studies, 11 RNAs and four viral proteins have been detected in PCV2-infected cells. Open reading frame (ORF) 4 is 180bp in length and has been identified at the transcription and the translation level. It overlaps completely with ORF3, which has a role in virus-induced apoptosis. In this study, start codon mutations (M1-PCV2) or in-frame termination mutations (M2-PCV2) were utilized to construct two ORF4-protein deficient viruses aiming to investigate its role in viral infection. The abilities of M1-PCV2 and M2-PCV2 to replicate, transcribe, express viral proteins, and to cause cellular apoptosis were evaluated. Viral DNA replication curves supported that the ORF4 protein is not essential for viral replication, but inhibits viral replication in the early stage of infection. Comparison of the expression level of ORF3 mRNA among wild-type and ORF4-deficient viruses in infected PK-15 cell demonstrated enhanced ORF3 transcription of both ORF4 mutants suggesting that the ORF4 protein may play an important role by restricting ORF3 transcription thereby preventing virus-induced apoptosis. This is further confirmed by the significantly higher caspase 3 and 8 activities in M1-PCV2 and M2-PCV2 compared to wild-type PCV2. Furthermore, the role of ORF4 in cell apoptosis and a possible interaction with the ORF1 associated Rep protein could perhaps explain the rapid viral growth in the early stage of infection and the higher expression level of ORF1 mRNA in ORF4 protein deficient PCV2 mutants.

Interaction of heavy metals and pyrene on their fates in soil and tall fescue (Festuca arundinacea).

90-Day growth chamber experiments were performed to investigate the interactive effect of pyrene and heavy metals (Cu, Cd, and Pb) on the growth of tall fescue and its uptake, accumulation, and dissipation of heavy metals and pyrene. Results show that plant growth and phytomass production were impacted by the interaction of heavy metals and pyrene. They were significantly decreased with heavy metal additions (100-2000 mg/kg), but they were only slightly declined with pyrene spiked up to 100 mg/kg. The addition of a moderate dosage of pyrene (100 mg/kg) lessened heavy metal toxicity to plants, resulting in enhanced plant growth and increased metal accumulation in plant tissues, thus improving heavy metal removal by plants. In contrast, heavy metals always reduced both plant growth and pyrene dissipation in soils. The chemical forms of Cu, Cd, and Pb in plant organs varied with metal species and pyrene addition. The dissipation and mineralization of pyrene tended to decline in both planted soil and unplanted soils with the presence of heavy metals, whereas they were enhanced with planting. The results demonstrate the complex interactive effects of organic pollutants and heavy metals on phytoremediation in soils. It can be concluded that, to a certain extent, tall fescue may be useful for phytoremediation of pyrene-heavy metal-contaminated sites. Further work is needed to enhance methods for phytoremediation of heavy metal-organics co-contaminated soil.

Biodegradation of decabromodiphenyl ether (BDE-209) by a metal resistant strain, Bacillus cereus JP12.

A metal resistant bacterial strain, Bacillus cereus JP12, could use decabromodiphenyl ether (BDE-209) as the sole carbon and energy source for growth in mineral salt medium. Under the conditions of pH 6.0, 30°C, 150 rpm and an inoculum of OD600=0.6, more than 88% of the initial BDE-209 (1mg/L) was degraded after 12 days. The addition of appropriate surfactants and additional carbon sources could enhance the biodegradation efficiency of BDE-209. The presence of Cu(2+) (≤ 8 mg/L) and Zn(2+) (≤ 15 mg/L) provided a slight stimulating effect on BDE-209 removal. However, BDE-209 biodegradation efficiency was decreased when adding higher levels of metals due to reduced substrate availability caused by excess metal adsorption into the cell surface. Biosorption of heavy metals by JP12 led to release of light metals such as K(+) and Na(+). A BDE-209 biodegradation pathway was proposed on the basis of metabolite identification.

Bacterial community diversity in a low-permeability oil reservoir and its potential for enhancing oil recovery.

The diversity of indigenous bacterial community and the functional species in the water samples from three production wells of a low permeability oil reservoir was investigated by high-throughput sequencing technology. The potential of application of indigenous bacteria for enhancing oil recovery was evaluated by examination of the effect of bacterial stimulation on the formation water-oil-rock surface interactions and micromodel test. The results showed that production well 88-122 had the most diverse bacterial community and functional species. The broth of indigenous bacteria stimulated by an organic nutrient activator at aerobic condition changed the wettability of the rock surface from oil-wet to water-wet. Micromodel test results showed that flooding using stimulated indigenous bacteria following water flooding improved oil recovery by 6.9% and 7.7% in fractured and unfractured micromodels, respectively. Therefore, the zone of low permeability reservoir has a great potential for indigenous microbial enhanced oil recovery.

Identification and characterization of two novel transcription units of porcine circovirus 2.

Porcine circovirus type 2 (PCV2) infection is associated with porcine circovirus-associated diseases in pigs, which is a serious threat to the swine industry worldwide. To date, only three open reading frames (ORFs) within the PCV2 genome have been reported: ORF1 codes for two replicase proteins (Rep and Rep'), ORF2 for the structural protein (Cap), and ORF3 for a protein implicated in cellular apoptosis. In this study, based on transcription analysis of ORF3 mRNA, a potential ORF4 mRNA was detected and characterized by real-time RT-PCR and rapid amplification of cDNA ends analysis. The results indicate that the ORF4 gene is expressed at the level of transcription in the PCV2-infected cells. In addition, a novel ORF3 associated (ORF3') mRNA was identified during virus replication in PK15 cells. Moreover, a 3' poly(A) addition signal sequence (AUUAAA, nt 258-263) was found 10-30 nucleotides upstream of the cleavage site in the novel ORF4 mRNA in the complementary-strand of the PCV2 genome. Furthermore, alternate trans-splicing was identified in the ORF3' mRNA between orientation diverse transcripts with typical GT-AG donor/acceptor junctions. Similar strategies as in this work can be applied to examine the transcription of other potential ORFs in PCV in the future.

Solar wind origin in coronal funnels.

The origin of the solar wind in solar coronal holes has long been unclear. We establish that the solar wind starts flowing out of the corona at heights above the photosphere between 5 megameters and 20 megameters in magnetic funnels. This result is obtained by a correlation of the Doppler-velocity and radiance maps of spectral lines emitted by various ions with the force-free magnetic field as extrapolated from photospheric magnetograms to different altitudes. Specifically, we find that Ne7+ ions mostly radiate around 20 megameters, where they have outflow speeds of about 10 kilometers per second, whereas C3+ ions with no average flow speed mainly radiate around 5 megameters. Based on these results, a model for understanding the solar wind origin is suggested.