Ubiquitination of DNA Damage-Stalled RNAPII Promotes Transcription-Coupled Repair.

Transcription-coupled nucleotide excision repair (TC-NER) is initiated by the stalling of elongating RNA polymerase II (RNAPIIo) at DNA lesions. The ubiquitination of RNAPIIo in response to DNA damage is an evolutionarily conserved event, but its function in mammals is unknown. Here, we identified a single DNA damage-induced ubiquitination site in RNAPII at RPB1-K1268, which regulates transcription recovery and DNA damage resistance. Mechanistically, RPB1-K1268 ubiquitination stimulates the association of the core-TFIIH complex with stalled RNAPIIo through a transfer mechanism that also involves UVSSA-K414 ubiquitination. We developed a strand-specific ChIP-seq method, which revealed RPB1-K1268 ubiquitination is important for repair and the resolution of transcriptional bottlenecks at DNA lesions. Finally, RPB1-K1268R knockin mice displayed a short life-span, premature aging, and neurodegeneration. Our results reveal RNAPII ubiquitination provides a two-tier protection mechanism by activating TC-NER and, in parallel, the processing of DNA damage-stalled RNAPIIo, which together prevent prolonged transcription arrest and protect against neurodegeneration.

Lessons learnt on the impact of an unprecedented soil decontamination program in Fukushima on contaminant fluxes.

In the context of elevated concerns related to nuclear accidents and warfare, the lessons learnt from the Fukushima Daiichi Nuclear Power Plant accident in 2011 are important. In particular, Japanese authorities implemented an ambitious decontamination program to reduce the air dose rate in order to facilitate the return of the local inhabitants to previously evacuated areas. This approach contrasts the strategy adopted in Chernobyl, where the most contaminated areas remain off limits. Nonetheless, the effectiveness of the Japanese decontamination strategy on the dispersion of radioactive contaminant fluxes across mountainous landscapes exposed to typhoons has not been quantified. Based on the unique combination of river monitoring and modeling in a catchment representative of the most impacted area in Japan, we demonstrate that decontamination of 16% of the catchment area resulted in a decrease of 17% of sediment-bound radioactive fluxes in rivers. Decontamination operations were therefore relatively effective, although they could only be conducted in a small part of the area due to the dominance of steep forested slopes. In fact, 67% of the initial radiocesium contamination was calculated to remain stored in forested landscapes, which may contribute to future downstream radiocesium dispersion during erosive events. Given that only a limited proportion of the initial population had returned in 2019 (~30%), it raises the question as to whether decontaminating a small percentage of the contaminated area was worth the effort, the price, and the amount of waste generated?

Chondroitin 4-O-sulfation regulates hippocampal perineuronal nets and social memory.

Glycan alterations are associated with aging, neuropsychiatric, and neurodegenerative diseases, although the contributions of specific glycan structures to emotion and cognitive functions remain largely unknown. Here, we used a combination of chemistry and neurobiology to show that 4-O-sulfated chondroitin sulfate (CS) polysaccharides are critical regulators of perineuronal nets (PNNs) and synapse development in the mouse hippocampus, thereby affecting anxiety and cognitive abilities such as social memory. Brain-specific deletion of CS 4-O-sulfation in mice increased PNN densities in the area CA2 (cornu ammonis 2), leading to imbalanced excitatory-to-inhibitory synaptic ratios, reduced CREB activation, elevated anxiety, and social memory dysfunction. The impairments in PNN densities, CREB activity, and social memory were recapitulated by selective ablation of CS 4-O-sulfation in the CA2 region during adulthood. Notably, enzymatic pruning of the excess PNNs reduced anxiety levels and restored social memory, while chemical manipulation of CS 4-O-sulfation levels reversibly modulated PNN densities surrounding hippocampal neurons and the balance of excitatory and inhibitory synapses. These findings reveal key roles for CS 4-O-sulfation in adult brain plasticity, social memory, and anxiety regulation, and they suggest that targeting CS 4-O-sulfation may represent a strategy to address neuropsychiatric and neurodegenerative diseases associated with social cognitive dysfunction.

Structure of mycobacterial ergothioneine-biosynthesis C-S lyase EgtE.

L-ergothioneine is widely distributed among various microbes to regulate their physiology and pathogenicity within complex environments. One of the key steps in the ergothioneine-biosynthesis pathway, the C-S bond cleavage reaction, uses the pyridoxal 5'-phosphate dependent C-S lyase to produce the final product L-ergothioneine. Here, we present the crystallographic structure of the ergothioneine-biosynthesis C-S lyase EgtE from Mycobacterium smegmatis (MsEgtE) represents the first published structure of ergothioneine-biosynthesis C-S lyases in bacteria and shows the effects of active site residues on the enzymatic reaction. The MsEgtE and the previously reported ergothioneine-biosynthesis C-S lyase Egt2 from Neurospora crassa (NcEgt2) fold similarly. However, discrepancies arise in terms of substrate recognition, as observed through sequence and structure comparison of MsEgtE and NcEgt2. The structural-based sequence alignment of the ergothioneine-biosynthesis C-S lyase from fungi and bacteria shows clear distinctions among the recognized substrate residues, but Arg348 is critical and an extremely conserved residue for substrate recognition. The α14 helix is exclusively found in the bacteria EgtE, which represent the most significant difference between bacteria EgtE and fungi Egt2, possibly resulting from the convergent evolution of bacteria and fungi.

GGA1 interacts with the endosomal Na+/H+ exchanger NHE6 governing localization to the endosome compartment.

Mutations in the endosomal Na+/H+ exchanger 6 (NHE6) cause Christianson syndrome, an X-linked neurological disorder. NHE6 functions in regulation of endosome acidification and maturation in neurons. Using yeast two-hybrid screening with the NHE6 carboxyl terminus as bait, we identify Golgi-associated, gamma adaptin ear-containing, ADP-ribosylation factor (ARF) binding protein 1 (GGA1) as an interacting partner for NHE6. We corroborated the NHE6-GGA1 interaction using: coimmunoprecipitation; overexpressed constructs in mammalian cells; and coimmunoprecipitation of endogenously expressed GGA1 and NHE6 from neuroblastoma cells, as well as from the mouse brain. We demonstrate that GGA1 interacts with organellar NHEs (NHE6, NHE7, and NHE9) and that there is significantly less interaction with cell-surface localized NHEs (NHE1 and NHE5). By constructing hybrid NHE1/NHE6 exchangers, we demonstrate the cytoplasmic tail of NHE6 interacts most strongly with GGA1. We demonstrate the colocalization of NHE6 and GGA1 in cultured, primary hippocampal neurons, using super-resolution microscopy. We test the hypothesis that the interaction of NHE6 and GGA1 functions in the localization of NHE6 to the endosome compartment. Using subcellular fractionation experiments, we show that NHE6 is mislocalized in GGA1 KO cells, wherein we find less NHE6 in endosomes, but more NHE6 transport to lysosomes, and more Golgi retention of NHE6, with increased exocytosis to the surface plasma membrane. Consistent with NHE6 mislocalization, and Golgi retention, we find the intraluminal pH in Golgi to be alkalinized in GGA1-null cells. Our study demonstrates a new interaction between NHE6 and GGA1 which functions in the localization of this intracellular NHE to the endosome compartment.

Carbon disulfide: A redox mediator for organodisulfides in redox flow batteries.

Organodisulfides (RSSR) are a class of promising active materials for redox flow batteries (RFBs). However, their sluggish kinetics and poor cyclic stability remain a formidable challenge. Here, we propose carbon disulfide (CS2) as a unique redox mediator involving reversible C-S bond formation/breakage to facilitate the reduction reaction of organodisulfides in RFBs. In the discharge of RSSR, CS2 interacts with the negatively charged RSSR-• to promote cleavage of the S-S bond by reducing about one-third of the energy barrier, forming RSCS2Li. In the recharge, CS2 is unbonded from RSCS2Li while RSSR is regenerated. Meanwhile, the redox mediator can also be inserted into the molecular structure of RSSR to form RSCS2SR/RSCS2CS2SR, and these new active materials with lower energy barriers can further accelerate the reaction kinetics of RSSR. With CS2, phenyl disulfide exhibits an exceptional rate capability and cyclability of 500 cycles. An average energy efficiency of >90% is achieved. This strategy provides a unique redox-mediating pathway involving C-S bond formation/breakage with the active species, which is different from those used in lithium-oxygen or other batteries.

Lead-Free Cs2AgBiBr6/TiO2 S-Scheme Heterojunction for Efficient Photocatalytic Antibiotic Rifampicin Degradation.

Exploring efficient and stable halide perovskite-based photocatalysts is a great challenge due to the balance between the photocatalytic performance, toxicity, and intrinsic chemical instability of the materials. Here, the environmentally friendly lead-free perovskite Cs2AgBiBr6 confined in the mesoporous TiO2 crystal matrix has been designed to enhance the charge carrier extraction and utilization for efficient photocatalytic rifampicin degradation. The as-prepared Cs2AgBiBr6/TiO2 catalyst was stable in air for over 500 days. An S-scheme heterojunction was formed between the (004) plane of Cs2AgBiBr6 and the (101) plane of TiO2 through the Bi-O-Br bonds. The built-in electric field at the interface efficiently promoted the photoinduced charge separation and carrier extraction. The Cs2AgBiBr6/TiO2-200 showed a 92.83% degradation efficiency of rifampicin within 80 min under simulated sunlight illumination (AM 1.5G 100 mW cm-2). This work offers an effective way for the construction of halide perovskite-based photocatalysts with high photocatalytic performance, good stability, and low toxicity simultaneously.

Biexciton Emission in CsPbBr3 Nanocrystals: Polar Facet Matters.

The metal halide perovskite nanocrystals exhibit a remarkable tolerance to midgap defect states, resulting in high photoluminescence quantum yields. However, the potential of these nanocrystals for applications in display devices is hindered by the suppression of biexcitonic emission due to various Auger recombination processes. By adopting single-particle photoluminescence spectroscopy, herein, we establish that the biexcitonic quantum efficiency increases with the increase in the number of facets on cesium lead bromide perovskite nanocrystals, progressing from cube to rhombic dodecahedron to rhombicuboctahedron nanostructures. The observed enhancement is attributed mainly to an increase in their surface polarity as the number of facets increases, which reduces the Coulomb interaction of charge carriers, thereby suppressing Auger recombination. Moreover, Auger recombination rate constants obtained from the time-gated photon correlation studies exhibited a discernible decrease as the number of facets increased. These findings underscore the significance of facet engineering in fine-tuning biexciton emission in metal halide perovskite nanocrystals.

Defect Density and Atomic Defect Recognition in the Middle Layer of a Trilayer MoS2 Stack.

Molybdenum disulfide (MoS2) is one of the most intriguing two-dimensional materials, and moreover, its single atomic defects can significantly alter the properties. These defects can be both imaged and engineered using spherical and chromatic aberration-corrected high-resolution transmission electron microscopy (CC/CS-corrected HRTEM). In a few-layer stack, several atoms are vertically aligned in one atomic column. Therefore, it is challenging to determine the positions of missing atoms and the damage cross-section, particularly in the not directly accessible middle layers. In this study, we introduce a technique for extracting subtle intensity differences in CC/CS-corrected HRTEM images. By exploiting the crystal structure of the material, our method discerns chalcogen vacancies even in the middle layer of trilayer MoS2. We found that in trilayer MoS2 the middle layer's damage cross-section is about ten times lower than that in the monolayer. Our findings could be essential for the application of few-layer MoS2 in nanodevices.

CSP7 Protects Alveolar Epithelial Cells by Targeting p53-Fibrinolytic Pathways During Lung Injuries.

Impaired alveolar epithelial regeneration in patients with idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) is attributed to telomere dysfunction in type II alveolar epithelial cells (A2Cs). Genetic susceptibility, aging, and toxicant exposures, including tobacco smoke (TS), contribute to telomere dysfunction in A2Cs. Here we investigated whether improvement of telomere function plays a role in CSP7-mediated protection of A2Cs against ongoing senescence and apoptosis during bleomycin (BLM)-induced pulmonary fibrosis (PF) as well as alveolar injury caused by chronic TS exposure. We found a significant telomere shortening in A2Cs isolated from IPF and COPD lungs in line with other studies. These cells showed increased p53 in addition to its post-translational modification with induction of activated caspase-3 and ß-galactosidase, suggesting a p53-mediated loss of A2C renewal. Further, we found increased expression of SIAH-1, a p53-inducible E3 ubiquitin ligase known to down-regulate telomere repeats binding factor 2 (TRF2). Consistent with the loss of TRF2 and upregulation of TRF1, telomerase reverse transcriptase (TERT) was downregulated in A2Cs. A2Cs from fibrotic lungs of mice either repeatedly instilled with BLM or isolated from chronic TS exposure-induced lung injury model showed reduced telomere length along with induction of p53, PAI-1, SIAH1 and TRF1 as well as loss of TRF2 and TERT, which were reversed in wild-type mice after treatment with CSP7. Interestingly, PAI-1-/- mice, or those lacking microRNA-34a expression in A2Cs, resisted telomere dysfunction, while uPA-/- mice failed to respond to CSP7 treatment, suggesting p53-microRNA-34a feed-forward induction and p53-uPA pathway contributes to telomere dysfunction.

PpHY5 is involved in anthocyanin coloration in the peach flesh surrounding the stone.

Red coloration around the stone (Cs) is an important trait of canned peaches (Prunus persica). In this study, an elongated hypocotyl 5 gene in peach termed PpHY5 was identified to participate in the regulation of the Cs trait. The E3 ubiquitin ligase PpCOP1 was expressed in the flesh around the stone and could interact with PpHY5. Although HY5 is known to be degraded by COP1 in darkness, the PpHY5 gene was activated in the flesh tissue surrounding the stone at the ripening stages and its expression was consistent with anthocyanin accumulation. PpHY5 was able to promote the transcription of PpMYB10.1 through interacting with its partner PpBBX10. Silencing of PpHY5 in the flesh around the stone caused a reduction in anthocyanin pigmentation, while transient overexpression of PpHY5 and PpBBX10 resulted in anthocyanin accumulation in peach fruits. Moreover, transgenic Arabidopsis seedlings overexpressing PpHY5 showed increased anthocyanin accumulation in leaves. Our results improve our understanding of the mechanisms of anthocyanin coloration in plants.

Alpha-synuclein modulates the repair of genomic DNA double-strand breaks in a DNA-PKcs-regulated manner.

α-synuclein (αSyn) is a presynaptic and nuclear protein that aggregates in important neurodegenerative diseases such as Parkinson's Disease (PD), Parkinson's Disease Dementia (PDD) and Lewy Body Dementia (LBD). Our past work suggests that nuclear αSyn may regulate forms of DNA double-strand break (DSB) repair in HAP1 cells after DNA damage induction with the chemotherapeutic agent bleomycin1. Here, we report that genetic deletion of αSyn specifically impairs the non-homologous end-joining (NHEJ) pathway of DSB repair using an extrachromosomal plasmid-based repair assay in HAP1 cells. Notably, induction of a single DSB at a precise genomic location using a CRISPR/Cas9 lentiviral approach also showed the importance of αSyn in regulating NHEJ in HAP1 cells and primary mouse cortical neuron cultures. This modulation of DSB repair is regulated by the activity of the DNA damage response signaling kinase DNA-PKcs, since the effect of αSyn loss-of-function is reversed by DNA-PKcs inhibition. Together, these findings suggest that αSyn plays an important physiologic role in regulating DSB repair in both a transformed cell line and in primary cortical neurons. Loss of this nuclear function may contribute to the neuronal genomic instability detected in PD, PDD and LBD and points to DNA-PKcs as a potential therapeutic target.

Dual CTLA-4 and PD-1 checkpoint blockade using CS1002 and CS1003 (nofazinlimab) in patients with advanced solid tumors: A first-in-human, dose-escalation, and dose-expansion study.

BACKGROUND: This study investigated the safety and efficacy of an anti-CTLA-4 monoclonal antibody (CS1002) as monotherapy and in combination with an anti-PD-1 monoclonal antibody (CS1003) in patients with advanced/metastatic solid tumors. METHODS: The phase 1 study involved phase 1a monotherapy dose-escalation (part 1) and phase 1b combination therapy dose escalation (part 2) and expansion (part 3). Various dosing schedules of CS1002 (0.3, 1, or 3 mg/kg every 3 weeks, or 3 mg/kg every 9 weeks) were evaluated with 200 mg CS1003 every 3 weeks in part 3. RESULTS: Parts 1, 2, and 3 included a total of 13, 18, and 61 patients, respectively. No dose-limiting toxicities or maximum tolerated doses were observed. Treatment-related adverse events (TRAEs) were reported in 30.8%, 83.3%, and 75.0% of patients in parts 1, 2, and 3, respectively. Grade ≥3 TRAEs were experienced by 15.4%, 50.0%, and 18.3% of patients in each part. Of 61 patients evaluable for efficacy, 23 (37.7%) achieved objective responses in multiple tumor types. Higher objective response rates were observed with conventional and high-dose CS1002 regimens (1 mg/kg every 3 weeks or 3 mg/kg every 9 weeks) compared to low-dose CS1002 (0.3 mg/kg every 3 weeks) in microsatellite instability-high/mismatch repair-deficient tumors, melanoma, and hepatocellular carcinoma (50.0% vs. 58.8%, 14.3% vs. 42.9%, and 0% vs. 16.7%). CONCLUSION: CS1002, as monotherapy, and in combination with CS1003, had a manageable safety profile across a broad dosing range. Promising antitumor activities were observed in patients with immune oncology (IO)-naive and IO-refractory tumors across CS1002 dose levels when combined with CS1003, supporting further evaluation of this treatment combination for solid tumors. PLAIN LANGUAGE SUMMARY: CS1002 is a human immunoglobulin (Ig) G1 monoclonal antibody that blocks the interaction of CTLA-4 with its ligands and increases T-cell activation/proliferation. CS1003, now named nofazinlimab, is a humanized, recombinant IgG4 monoclonal antibody that blocks the interaction between human PD-1 and its ligands. In this original article, we determined the safety profile of CS1002 as monotherapy and in combination with CS1003. Furthermore, we explored the antitumor activity of the combination in anti-programmed cell death protein (ligand)-1 (PD-[L]1)-naive microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) pan tumors, and anti-PD-(L)1-refractory melanoma and hepatocellular carcinoma (HCC). CS1002 in combination with CS1003 had manageable safety profile across a broad dosing range and showed promising antitumor activities across CS1002 dose levels when combined with CS1003. This supports further assessment of CS1002 in combination with CS1003 for the treatment of solid tumors.

HCOO- Doping-Induced Multiexciton Emissions in Cs3Cu2I5 Crystals for Efficient X-Ray Scintillation.

Self-trapped exciton (STE) luminescence, typically associated with structural deformation of excited states, has attracted significant attention in metal halide materials recently. However, the mechanism of multiexciton STE emissions in certain metal halide crystals remains largely unexplored. This study investigates dual luminescence emissions in HCOO- doped Cs3Cu2I5 single crystals using transient and steady-state spectroscopy. The dual emissions are attributed to intrinsic STE luminescence originating from the host lattice and extrinsic STE luminescence induced by external dopants, respectively, each of which can be triggered independently at distinct energy levels. Theoretical calculations reveal that multiexciton emission originates from structural distortion of the host and dopant STEs within the 0D lattice in their respective excited states. By meticulously tuning the excitation wavelength and selectively exciting different STEs, the dynamic alteration of color change in Cs3Cu2I5:HCOO- crystals is demonstrated. Ultimately, owing to an extraordinarily high photoluminescence quantum yield (99.01%) and a diminished degree of self-absorption in Cs3Cu2I5:HCOO- crystals, they exhibit remarkable X-ray scintillation characteristics with light yield being improved by 5.4 times as compared to that of pristine Cs3Cu2I5 crystals, opening up exciting avenues for achieving low-dose X-ray detection and imaging.

Construction of Cs2AgBiCl6/COF Heterojunction for Boosted Photocatalytic Thioester Oxidation.

Lead-free halide perovskites as a new kind of potential candidate for photocatalytic organic synthesis have attracted much attention recently. The rational heterojunction construction is regarded as an efficient strategy to delicately regulate their catalytic performances. Herein, a semi-conductive covalent organic framework (COF) nanosheet, C4N, is employed as the functional component to construct Cs2AgBiCl6/C4N (CABC/C4N) heterojunction. It is found that the C4N nanosheets with rich surface functional groups can serve as heterogeneous nucleation sites to manipulate the growth of CABC nanocrystals and afford close contact between each other, therefore facilitate the transfer and spatial separation of photogenerated charge carriers, as verified by in situ X-ray photoelectronic spectroscopy and Kelvin probe force microscopy. Moreover, the oxygen affinity of C4N endows the heterojunctions with outstanding aerobic reactivity, thus improving the photocatalytic performance largely. The optimal CABC/C4N heterojunction delivers a thioanisole conversion efficiency of 100% after 6 h, which is 2.2 and 7.7-fold of that of CABC and C4N. This work provides a new ideal for the design and application of lead-free perovskite heterojunction photocatalysts for organic reactions.

Managing Interfacial Defects and Charge-Carriers Dynamics by a Cesium-Doped SnO2 for Air Stable Perovskite Solar Cells.

A high-quality nanostructured tin oxide (SnO2) has garnered massive attention as an electron transport layer (ETL) for efficient perovskite solar cells (PSCs). SnO2 is considered the most effective alternative to titanium oxide (TiO2) as ETL because of its low-temperature processing and promising optical and electrical characteristics. However, some essential modifications are still required to further improve the intrinsic characteristics of SnO2, such as mismatch band alignments, charge extraction, transportation, conductivity, and interfacial recombination losses. Herein, an inorganic-based cesium (Cs) dopant is used to modify the SnO2 ETL and to investigate the impact of Cs-dopant in curing interfacial defects, charge-carrier dynamics, and improving the optoelectronic characteristics of PSCs. The incorporation of Cs contents efficiently improves the perovskite film quality by enhancing the transparency, crystallinity, grain size, and light absorption and reduces the defect states and trap densities, resulting in an improved power conversion efficiency (PCE) of ≈22.1% with Cs:SnO2 ETL, in-contrast to pristine SnO2-based PSCs (20.23%). Moreover, the Cs-modified SnO2-based PSCs exhibit remarkable environmental stability in a relatively higher relative humidity environment (>65%) and without encapsulation. Therefore, this work suggests that Cs-doped SnO2 is a highly favorable electron extraction material for preparing highly efficient and air-stable planar PSCs.

Rubidium Doped Cs2AgBiBr6 Hierarchical Microsphere for Enhanced Photocatalytic CO2 Reduction.

Halide perovskites have garnered significant attention for their unique optoelectronic properties in solar-to-fuel conversions. However, the efficiency of halide perovskites in the field of photocatalytic CO2 reduction is largely limited by serious charge recombination and a lack of efficient active sites. In this work, a rubidium (Rb) doped Cs2AgBiBr6 (Rb:CABB) hierarchical microsphere is developed for photocatalytic CO2 reduction. Experimental and theoretical analysis discloses that partially substituting Rb+ for Ag+ can effectively modulate the electronic structure of CABB, favoring charge separation and making adjacent Bi atoms an electron-rich active site. Further investigations indicated that Rb doping also reduces the energy barriers of the rate-determining step in CO2 reduction. As a result, Rb:CABB demonstrated an enhanced CO yield compared to its undoped counterpart. This work presents a promising approach to optimizing the electronic structures of photocatalysts and paving a new way for exploring halide perovskites for photocatalytic CO2 reduction.

Palladium-Doped Cs2AgBiBr6 with 1300 nm Near-Infrared Photoresponse.

Lead-free halide double perovskite (HDP) Cs2AgBiBr6 has set a benchmark for research in HDP photoelectric applications due to its attractive optoelectronic properties. However, its narrow absorption range is a key limitation of this material. Herein, a novel dopant, palladium (Pd), is doped into Cs2AgBiBr6 and significantly extends the absorption to ≈1400 nm. Pd2+ ions are partially doped in the host lattice, most probably replacing Ag atoms and introducing a sub-bandgap state within the host bandgap, as indicated by the combination of spectroscopical measurements and theoretical calculations. Importantly, this sub-bandgap state extends the photoresponse of Cs2AgBiBr6 up to the NIR-II region of 1300 nm, setting a new record for HDPs. This work demonstrates a novel and efficient dopant for HDPs and highlights the effectiveness of employing a sub-bandgap to broaden the absorption of HDPs, shedding new light on tailoring large bandgap HDPs for NIR optoelectronic applications.

Anchoring Carbon Spheres on Titanium Dioxide Modified Commercial Polyethylene (PE) Separator to Suppress Lithium Dendrites for Lithium Metal Batteries.

Lithium dendrites are easily generated for excessively-solved lithium ions (Li+) inside the lithium metal batteries, which will lead serious safety issues. In this experiment, carbon spheres (CS) are successfully anchored on TiO2 (CS@TiO2) in the hydrothermal polymerization, which is filtrated on the commercial PE separator (CS@TiO2@PE). The negative charge in CS can suppress random diffusion of anions through electrostatic interactions. Density functional theory (DFT) calculations show that CS contributes to the desolvation of Li+, thereby increasing the migration rate of Li+. Furthermore, TiO2 exhibits high affinity to liquid electrolytes and acts as a physical barrier to lithium dendrite formation. CS@TiO2 is a combination of the advantages of CS and TiO2. As results, the Li+ transference number of the CS@TiO2@PE separator can be promoted to 0.63. The Li||Li cell with the CS@TiO2@PE separator exhibits a stable cycle performance for more than 600 h and lower polarization voltage (17 mV) at 1 mA cm-2. The coulombic efficiency (CE) of the Li||Cu cells employe the CS@TiO2@PE separator is 81.63% over 130 cycles. The discharge capacity of LiFePO4||Li cells based on the CS@TiO2@PE separator is 1.73 mAh (capacity retention = 91.53% after 260 cycles). Thus, the CS@TiO2 layer inhibits lithium dendrite formation.

In Situ Formation of SnSe2/SnSe Vertical Heterostructures toward Polarization Selectable Band Alignments.

2D van der Waals (vdW) layered semiconductor vertical heterostructures with controllable band alignment are highly desired for nanodevice applications including photodetection and photovoltaics. However, current 2D vdW heterostructures are mainly obtained via mechanical exfoliation and stacking process, intrinsically limiting the yield and reproducibility, hardly achieving large-area with specific orientation. Here, large-area vdW-epitaxial SnSe2/SnSe heterostructures are obtained by annealing layered SnSe. These in situ Raman analyses reveal the optimized annealing conditions for the phase transition of SnSe to SnSe2. The spherical aberration-corrected transmission electron microscopy investigations demonstrate that layered SnSe2 epitaxially forms on SnSe surface with atomically sharp interface and specific orientation. Optical characterizations and theoretical calculations reveal valley polarization of the heterostructures that originate from SnSe, suggesting a naturally adjustable band alignment between type-II and type-III, only relying on the polarization angle of incident lights. This work not only offers a unique and accessible approach to obtaining large-area SnSe2/SnSe heterostructures with new insight into the formation mechanism of vdW heterostructures, but also opens the intriguing optical applications based on valleytronic nanoheterostructures.