Boosted Lithium-Ion Transport Kinetics in n-Type Siloxene Anodes Enabled by Selective Nucleophilic Substitution of Phosphorus

Doped two-dimensional(2D)materials hold significant promise for advancing many technologies,such as microelectronics,optoelectronics,and energy storage.Herein,n-type 2D oxidized Si nanosheets,namely n-type siloxene(n-SX),are employed as Li-ion battery anodes.Via thermal evaporation of sodium hypophosphite at 275℃,P atoms are effectively incorporated into siloxene(SX)without compromising its 2D layered morphology and unique Kautsky-type crystal structure.Further,selective nucleophilic substitution occurs,with only Si atoms being replaced by P atoms in the O_(3)≡Si-H tetrahedra.The resulting n-SX possesses two delocalized electrons arising from the presence of two electron donor types:(i)P atoms residing in Si sites and(ii)H vacancies.The doping concentrations are varied by controlling the amount of precursors or their mean free paths.Even at 2000 mA g^(-1),the n-SX electrode with the optimized doping concentration(6.7×10^(19) atoms cm^(-3))delivers a capacity of 594 mAh g^(-1) with a 73%capacity retention after 500 cycles.These improvements originate from the enhanced kinetics of charge transport processes,including electronic conduction,charge transfer,and solid-state diffusion.The approach proposed herein offers an unprecedented route for engineering SX anodes to boost Li-ion storage.

In situ infrared, Raman and X-ray spectroscopy for the mechanistic understanding of hydrogen evolution reaction

Hydrogen production by water reduction reactions has received considerable attention because hydrogen is considered a clean-energy carrier,key for a sustainable energy future.Computational methods have been widely used to study the reaction mechanism of the hydrogen evolution reaction(HER),but the calculation results need to be supported by experimental results and direct evidence to confirm the mechanistic insights.In this review,we discuss the fundamental principles of the in situ spectroscopic strategy and a theoretical model for a mechanistic understanding of the HER.In addition,we investigate recent studies by in situ Fourier transform infrared(FTIR),Raman spectroscopy,and X-ray absorption spectroscopy(XAS) and cover new findings that occur at the catalyst-electrolyte interface during HER.These spectroscopic strategies provide practical ways to elucidate catalyst phase,reaction intermediate,catalyst-electrolyte interface,intermediate binding energy,metal valency state,and coordination environment during HER.

Optimally arranged TiO_(2)@MoS_(2) heterostructures with effectively induced built-in electric field for high-performance lithium-sulfur batteries

To overcome the serious technological issues affecting lithium-sulfur(Li-S) batteries,such as sluggish sulfur redox kinetics and the detrimental shuttle effect,heterostructure engineering has been investigated as a strategy to effectively capture soluble lithium polysulfide intermediates and promote their conversion reaction by integrating highly polar metal oxides with catalytically active metals sulfides.However,to fully exploit the outstanding properties of heterostructure-based composites,their detailed structure and interfacial contacts should be designed rationally.Herein,optimally arranged TiO_(2)and MoS_(2)-based heterostructures(TiO_(2)@MoS_(2)) are fabricated on carbon cloth as a multifunctional interlayer to efficiently trap polysulfide intermediates and accelerate their redox kinetics.Owing to the synergistic effects between TiO_(2)and MoS_(2)and the uniform heterointerface distribution that induces the ideally oriented built-in electric field,Li-S batteries with TiO_(2)@MoS_(2)interlayers exhibit high rate capability(601 mA h g^(-1)at 5 C),good cycling stability(capacity-fade rate of 0.067% per cycle over 500 cycles at2 C),and satisfactory areal capacity(5.2 mA h cm^(-2)) under an increased sulfur loading of 5.2 mg cm^(-2).Moreover,by comparing with a MoS_(2)@TiO_(2)interlayer composed of reversely arranged heterostructures,the effect of the built-in electric field’s direction on the electrocatalytic reactions of polysulfide intermediates is thoroughly investigated for the first time.The superior electrocatalytic activities of the rationally arranged TiO_(2)@MoS_(2)interlayer demonstrate the importance of optimizing the built-in electric field of heterostructures for producing high-performance Li-S batteries.

Programmed death ligand-1 expression and its prognostic role in esophageal squamous cell carcinoma

AIM To investigate the expression and prognostic role of programmed death ligand-1(PD-L1) in locally advanced esophageal squamous cell carcinoma(ESCC).METHODS A total of 200 patients with ESCC who underwent radical esophagectomy with standard lymphadenectomy as the initial definitive treatment in Seoul National University Hospital from December 2000 to April 2013 were eligible for this analysis. Tissue microarrays were constructed by collecting tissue cores from surgical specimens, and immunostained with antibodies directed against PD-L1, p16, and c-Met. Medical records were reviewed retrospectively to assess clinical outcomes. Patients were divided into two groups by PD-L1 status, and significant differences in clinicopathologic characteristics between the two groups were assessed. RESULTS Tumor tissues from 67 ESCC patients(33.5%) were PDL1-positive. Positive p16 expression was observed in 21 specimens(10.5%). The H-score for c-Met expression was ≥ 50 in 42 specimens(21.0%). Although PDL1-positivity was not significantly correlated with any clinical characteristics including age, sex, smoking/alcoholic history, stage, or differentiation, H-scores for c-Met expression were significantly associated with PDL1-positivity(OR = 2.34, 95%CI: 1.16-4.72, P = 0.017). PD-L1 expression was not significantly associated with a change in overall survival(P = 0.656). In contrast, the locoregional relapse rate tended to increase(P = 0.134), and the distant metastasis rate was significantly increased(HR = 1.72, 95%CI: 1.01-2.79, P = 0.028) in patients with PD-L1-positive ESCC compared to those with PD-L1-negative ESCC.CONCLUSION PD-L1 expression is positively correlated with c-Met expression in ESCC. PD-L1 may play a critical role in distant failure and progression of ESCC.

Proportion and clinical features of never-smokers with non-small cell lung cancer

Background: The proportion of never?smokers with non?small cell lung cancer(NSCLC) is increasing, but that in Korea has not been well addressed in a large population. We aimed to evaluate the proportion and clinical features of never?smokers with NSCLC in a large single institution.Methods: We analyzed clinical data of 1860 consecutive patients who were newly diagnosed with NSCLC between June 2011 and December 2014.Results: Of the 1860 NSCLC patients, 707(38.0%) were never?smokers. The proportions of women(83.7% vs. 5.6%) and adenocarcinoma(89.8% vs. 44.9%) were higher among never?smokers than among ever?smokers. Significantly more never?smokers were diagnosed at a younger median age(65 vs. 68 years, P < 0.001) and earlier stage(stage I–II, 44.5% vs. 38.9%, P < 0.001) a= 0.015) compared with ever?smokers. Epidermal growth factor receptor mutations(57.8% vs. 24.4%, Pnd anaplastic lymphoma kinase rearrangements(7.8% vs. 2.8%, P < 0.001) were more common in never?smokers, whereas Kirsten rat sarcoma viral oncogene homolog mutations(5.8% vs. 9.6%, P ntly encountered in never?smokers than in ever?smokers. Never?smokers showed longer su= 0.021) were less frequervival after adjust?ing for the favorable effects of younger age, female sex, adenocarcinoma histology, better performance status, early stage disease, being asymptomatic at diagnosis, received antitumor treatment, and the presence of driver mutations(hazard ratio, 0.624; 95% confidence interval, 0.460–0.848; P = 0.003).Conclusions: More than one?third of the Korean patients with NSCLC were never?smokers. NSCLC in never?smokers had different clinical characteristics and major driver mutations and resulted in longer overall survival compared with NSCLC in ever?smokers.

非吸烟非小细胞肺癌患者的比例和临床特征研究

背景与目的非小细胞肺癌(non?small cell lung cancer, NSCLC)患者中非吸烟患者的比例正在增加,但在韩国,这个人数众多的群体并没有得到很好的治疗。本研究旨对NSCLC非吸烟患者的比例和临床特征进行一个单中心评估。方法我们分析了从2011年6月到2014年12月所有新诊断为NSCLC的1860例患者的临床数据。结果在1860例NSCLC患者中,707例(38%)从不吸烟。非吸烟患者中女性(83.7%vs.5.6%)和腺癌(89.8%vs. 44.9%)的比例均高于吸烟患者。非吸烟患者与吸烟患者相比,中位年龄明显更低(65 vs. 68岁,P<0.001),早期肿瘤比例更高(I–II期,44.5%vs. 38.9%,P=0.015)。与吸烟患者相比,表皮生长因子受体突变(57.8%vs. 24.4%,P<0.001)和间变性淋巴瘤激酶重排(7.8%vs. 2.8%,P<0.001)在非吸烟患者中更常见,而Kirsten大鼠肉瘤病毒癌基因同源染色体的基因突变(5.8%vs. 9.6%,P=0.021)出现频率则较低。在对年龄低、女性、腺癌、体能更好、疾病早期、诊断时无症状、曾接受抗肿瘤治疗以及存在驱动基因突变等的有利影响进行校正后,非吸烟患者的生存期比吸烟患者更长(hazard ratio,0.624,95%CI:0.460–0.848; P=0.003)。结论韩国超过三分之一的NSCLC患者是非吸烟者。NSCLC非吸烟患者与吸烟患者相比,有着不同的临床特征和主要驱动基因突变,总生存期更长。

Heteroepitaxial growth of ZnO nanosheet bands on ZnCo204 submicron rods toward high-performance Li ion battery electrodes

We report the direct synthesis of ZnC0204 and ZnO/ZnC0204 submicron rod arrays grown on Ni foil current collectors via an ammonia-evaporation-induced method by controlling the ratio of Zn to Co. These three-dimensional （3D） hierar- chical self-supported nanostructures are composed of one-dimensional （1D） ZnCo204 rods and two-dimensional （2D） ZnO nanosheet bands perpendicular to the axis of the each ZnCo204 rod. We carefully deal with the heteroepitaxial growth mechanisms of hexagonal ZnO nanosheets from a crystallographic point of view. Furthermore, we demonstrate the ability of these high-surface-area ZnO/ZnCo204 heterostructured rods to enable improved electrolyte permeability and Li ion transfer, thereby enhancing their Li storage capability （-900 mA.h.g-1 at a rate of 45 mA.h.g-1） for Li ion battery electrodes.

Cobalt phosphide nanoarrays with crystalline-amorphous hybrid phase for hydrogen production in universal-pH

To accomplish mass hydrogen production by electrochemical water-splitting,it is a necessary to develop robust,highly active,stable,and cost-effective hydrogen evolution reaction(HER)electrocatalysts that perform comparably to Pt in the universal pH range.In this work,cobalt phosphide hybrid nanosheets supported on carbon felt(CoP HNS/CF)are presented,which exhibit the superior electrocatalytic hydrogen production under a universal-pH.In these nanosheets,a single CoP HNS is composed of polycrystalline CoP and oxygen-enriched amorphous Co-O-P phase.Benefiting from its unique nanoarchitecture,as-fabricated CoP HNS/CF exhibits a tremendous electrocatalytic HER activity and outperforms Pt/C as well as state-of-the-art CoP electrocatalysts in universal-pH.In acidic and neutral media,the CoP HNS/CF shows superior electrocatalytic activity while maintaining its original hybrid crystalline-amorphous phase and morphology.In alkaline medium,the unexpected phase and morphological reorganization of CoP HNS/CF results in outstanding electrocatalytic operation.CoP HNS/CF not only achieves high electrocatalytic activity and kinetics,but also a stable and long operating lifetime even under a high current density of 500 mA cm'2.Furthermore,the fabrication of CoP HNS/CF can be scaled up easily,and the large CoP HNS/CF electrode also exhibits similar electrocatalytic activity and stability.

Tailoring uniform γ-MnO2 nanosheets on highly conductive three-dimensional current collectors for high-performance supercapacitor electrodes

Recent efforts have focused on the fabrication and application of three- dimensional （3-D） nanoarchitecture electrodes, which can exhibit excellent electrochemical performance. Herein, a novel strategy towards the design and synthesis of size- and thickness-tunable two-dimensional （2-D） MnO2 nanosheets on highly conductive one-dimensional （l-D） backbone arrays has been developed via a facile, one-step enhanced chemical bath deposition （ECBD） method at a low temperature （-50 ℃）. Inclusion of an oxidizing agent, BrO3-, in the solution was crucial in controlling the heterogeneous nucleation and growth of the nanosheets, and in inducing the formation of the tailored and uniformly arranged nanosheet arrays. We fabricated supercapacitor devices based on 3-D MnO2 nanosheets with conductive Sb-doped SnO2 nanobelts as the backbone. They achieved a specific capacitance of 162 F·g-1 at an extremely high current density of 20 A·g% and good cycling stability that shows a capacitance retention of -92% of its initial value, along with a coulombic efficiency of almost 100% after 5,000 cycles in an aqueous solution of I M Na2SO4. The results were attributed to the unique hierarchical structures, which provided a short diffusion path of electrolyte ions by means of the 2-D sheets and direct electrical connections to the current collector by 1-D arrays as well as the prevention of aggregation by virtue of the well-aligned 3-D structure.

Surface-area-tuned, quantum-dot-sensitized heterostructured nanoarchitectures for highly efficient photoelectrodes

Harvesting solar energy to produce clean hydrogen from photoelectrolysis of water presents a valuable opportunity to find alternatives for fossil fuels. Three- dimensional nanoarchitecturing techniques can afford enhanced photoelectrochemical properties by improving geometrical and structural effects. Here, we report quantum-dot sensitized TiO2-Sb：SnO2 heterostructures as a model electrode to enable the optimization of the structural effects through the creation of a highly conductive pathway using a transparent conducting oxide （TCO）, coupled with a high surface area, by introducing branching and low interfacial resistance via an epitaxial relationship. An examination of various morphologies （dot, rod, and lamella shape） of TiO2 reveals that the rod-shaped TiO2-Sb：SnO2 is a more effective structure than the others. A photoelectrode fabricated using optimized CdS--TiO2-Sb：SnO2 produces a photocurrent density of 7.75 mA/cm2 at 0.4 V versus a reversible hydrogen electrode. These results demonstrate that constructing a branched heterostructure based on TCO can realize highperformance photoelectrochemical devices.

High-power and long-life supercapacitive performance of hierarchical, 3-D urchin-like W18049 nanostructure electrodes

We report the facile, one-pot synthesis of 3-D urchin-like W18O49 nanostructures （U-WO） via a simple solvothermal approach. An excellent supercapacitive performance was achieved by the U-WO because of its large Brunauer-Emmett- Teller （BET） specific surface area （ca. 123 m2.g-1） and unique morphological and structural features. The U-WO electrodes not only exhibit a high rate-capability with a specific capacitance （Csp） of -235 F·g-1 at a current density of 20 A.g-1, but also superior long-life performance for 1,000 cycles, and even up to 7,000 cycles, showing -176 F·g-1 at a high current density of 40 A.g-1.

Kinetic insight into perovskite La_(0.8)Sr_(0.2)VO_(3) nanofibers as an efficient electrocatalytic cathode for high-rate Li-O_(2) batteries

Efficient electrocatalysis at the cathode is essential for overcoming the limitations of Li-O_(2) batteries such as poor stability and low rate capability.Herein,we systematically studied the kinetic behavior of a Li-O_(2) battery comprising perovskite La_(0.8)Sr_(0.2)VO_(3) nanofibers formed by partial Sr-cation doping and V cations with multiple oxidation states.Compared with undoped LaVO_(3) and La_(0.8)Sr_(0.2)VO_(4) nanofibers,perovskite La_(0.8)Sr_(0.2)VO_(3) nanofibers exhibited an improved capacity of 2000 mA g^(-1),and a 20-times-longer cycle life in Li-O_(2) batteries.X-ray photoelectron spectroscopy,electron paramagnetic resonance spectroscopy,and photoluminescence analyses revealed that the performance variations mainly originated from crystal defects,which modulate oxygen reduction/evolution kinetics.Through in situ Raman analysis,we showed that these structural defects are closely related to the oxygen reduction/evolution behavior of La_(0.8)Sr_(0.2)VO_(3) nanofibers and result in fewer parasitic reactions.This study offers insights into the potential rate capability of Li-O_(2) batteries and related devices.