Time-dependent Kohn-Sham electron dynamics coupled with nonequilibrium plasmonic response via atomistic electromagnetic model.

Computational modeling of plasmon-mediated molecular photophysical and photochemical behaviors can help us better understand and tune the bound molecular properties and reactivity and make better decisions to design and control nanostructures. However, computational investigations of coupled plasmon-molecule systems are challenging due to the lack of accurate and efficient protocols to simulate these systems. Here, we present a hybrid scheme by combining the real-time time-dependent density functional theory (RT-TDDFT) approach with the time-domain frequency dependent fluctuating charge (TD-ωFQ) model. At first, we transform ωFQ in the frequency-domain, an atomistic electromagnetic model for the plasmonic response of plasmonic metal nanoparticles (PMNPs), into the time-domain and derive its equation-of-motion formulation. The TD-ωFQ introduces the nonequilibrium plasmonic response of PMNPs and atomistic interactions to the electronic excitation of the quantum mechanical (QM) region. Then, we combine TD-ωFQ with RT-TDDFT. The derived RT-TDDFT/TD-ωFQ scheme allows us to effectively simulate the plasmon-mediated "real-time" electronic dynamics and even the coupled electron-nuclear dynamics by combining them with the nuclear dynamics approaches. As a first application of the RT-TDDFT/TD-ωFQ method, we study the nonradiative decay rate and plasmon-enhanced absorption spectra of two small molecules in the proximity of sodium MNPs. Thanks to the atomistic nature of the ωFQ model, the edge effect of MNP on absorption enhancement has also been investigated and unveiled.

Single-cell SERS imaging of dual cell membrane receptors expression influenced by extracellular matrix stiffness.

Membrane receptors perform a diverse range of cellular functions, accounting for more than half of all drug targets. The mechanical microenvironment regulates cell behaviors and phenotype. However, conventional analysis methods of membrane receptors often ignore the effects of the extracellular matrix stiffness, failing to reveal the heterogeneity of cell membrane receptors expression. Herein, we developed an in-situ surface-enhanced Raman scattering (SERS) imaging method to visualize single-cell membrane receptors on substrates with different stiffness. Two SERS substrates, Au@4-mercaptobenzonitrile@Ag@Sgc8c and Au@4-pethynylaniline@Ag@SYL3c, were employed to specifically target protein tyrosine kinase-7 (PTK7) and epithelial cell adhesion molecule (EpCAM), respectively. The polyacrylamide (PA) gels with tunable stiffness (2.5-25 kPa) were constructed to mimic extracellular matrix. The simultaneous SERS imaging of dual membrane receptors on single cancer cells on substrates with different stiffness was achieved. Our findings reveal decreased expression of PTK7 and EpCAM on cells cultured on stiffer substrates and higher migration ability of the cells. The results elucidate the heterogeneity of membrane receptors expression of cells cultured on the substrates with different stiffness. This single-cell analysis method offers an in-situ platform for investigating the impacts of extracellular matrix stiffness on the expression of membrane receptors, providing insights into the role of cell membrane receptors in cancer metastasis.

Assembled RhRuFe Trimetallene for Water Electrolysis.

Industrializing water electrolyzers demands better electrocatalysts, especially for the anodic oxygen evolution reaction (OER). The prevailing OER catalysts are Ir or Ru-based nanomaterials, however, they still suffer from insufficient stability. An alternative yet considerably less explored approach is to upgrade Rh, a known stable but moderately active element for OER electrocatalysis, via rational structural engineering. Herein, a precise synthesis of assembled RhRuFe trimetallenes (RhRuFe TMs) with an average thickness of 1 nm for boosting overall water splitting catalysis is reported. Favorable mass transport and optimized electronic structure collectively render RhRuFe TMs with an improved OER activity of an overpotential of 330 mV to deliver 10 mA cm-2, which is significantly lower than the Rh/C control (by 601 mV) and reported Rh-based OER electrocatalysts. In particular, the RhRuFe TMs-based water splitting devices can achieve the current density of 10 mA cm-2 at a low voltage of 1.63 V, which is among the best in the Rh-based bifunctional catalysts for electrolyzers. The addition of Fe in RhRuFe TMs can modulate the strain/electron distribution of the multi-alloy, which regulates the binding energies of H* and OH* in hydrogen and oxygen evolution reactions for achieving the enhanced bifunctional OER and HER catalysis is further demonstrated.

SERS-based detection of the antibiotic ceftriaxone in spiked fresh plasma and microdialysate matrix by using silver-functionalized silicon nanowire substrates.

Therapeutic drug monitoring (TDM) is an important tool in precision medicine as it allows estimating pharmacodynamic and pharmacokinetic effects of drugs in clinical settings. An accurate, fast and real-time determination of the drug concentrations in patients ensures fast decision-making processes at the bedside to optimize the clinical treatment. Surface-enhanced Raman spectroscopy (SERS), which is based on the application of metallic nanostructured substrates to amplify the inherent weak Raman signal, is a promising technique in medical research due to its molecular specificity and trace sensitivity accompanied with short detection times. Therefore, we developed a SERS-based detection scheme using silicon nanowires decorated with silver nanoparticles, fabricated by means of top-down etching combined with chemical deposition, to detect the antibiotic ceftriaxone (CRO) in spiked fresh plasma and microdialysis samples. We successfully detected CRO in both matrices with an LOD of 94 µM in protein-depleted fresh plasma and 1.4 µM in microdialysate.

Cell Membrane-Anchored SERS Biosensor for the Monitoring of Cell-Secreted MMP-9 during Cell-Cell Communication.

Matrix metalloproteinase-9 (MMP-9), a proteolytic enzyme, degrades the extracellular matrix and plays a key role in cell communication. However, the real-time monitoring of cell-secreted MMP-9 during cell-cell communication remains a challenge. Herein, we developed a cell-based membrane-anchored surface-enhanced Raman scattering (SERS) biosensor using a Au@4-mercaptobenzonitrile (4-MBN) @Ag@peptide nanoprobe for the monitoring of cell-secreted MMP-9 during cell communication. The multifunctional nanoprobe was created with Au@4-MBN@Ag acting as an interference-free SERS substrate with high enhancement in which the peptide not only serves to anchor the cell membrane but also provides MMP-9-activatable cleaved peptide chains. MMP-9-mediated cleavage resulted in the detachment of the Au@4-MBN@Ag nanoparticles from the cell membrane, thereby decreasing the SERS signals of cancer cells. The cell membrane-anchored SERS biosensor enables the real-time monitoring of cell-secreted MMP-9 during the interaction of MCF-7 and HUVEC cells. This study successfully demonstrates the dynamic change of cell-secreted MMP-9 during the communication between MCF-7 cells and HUVEC cells. The proposed nanoprobe was also utilized to precisely evaluate the breast and hepatoma cancer cell aggressiveness. This study provides a novel strategy for real-time monitoring of MMP-9 secretion during cell communication, which is promising for the investigation of the mechanisms underlying different tumor processes.

Precise Strain Tuning Boosts Electrocatalytic Hydrogen Generation.

Strain engineering has been utilized as an effective approach to regulate the binding of reaction intermediates and modify catalytic behavior on noble metal nanocatalysts. However, the continuous, precise control of strain for a depiction of strain-activity correlation remains a challenge. Herein, Pd-based nanooctahedrons coated with two Ir overlayers are constructed, and subject to different postsynthetic treatments to alter the amount of H intercalated into Pd core for achieving three different surface strains (o-Pd/Ir-1.2%, o-Pd/Ir-1.7%, and o-Pd/Ir-2.1% NPs). It is demonstrated that the catalytic performances of o-Pd/Ir NPs display a volcano-shaped curve against strains toward the hydrogen evolution reaction (HER). Specifically, o-Pd/Ir-1.7% NPs exhibit superior catalytic performance with a mass activity of 9.38 A mgIr -1 at -0.02 V versus reversible hydrogen electrode, 10.8- and 18.8-fold higher than those of commercial Pt/C and Ir/C, respectively, making it one of the most active HER electrocatalysts reported to date. Density function theory calculations verify that the moderate tensile strain on Ir(111) surfaces plays a pivotal role in optimizing the H binding energy. This work highlights a new strategy for precise control over the surface strain of nanocrystals for more efficient electrocatalysis.

Cotton peroxisome-localized lysophospholipase counteracts the toxic effects of Verticillium dahliae NLP1 and confers wilt resistance.

Plasma membrane represents a critical battleground between plants and attacking microbes. Necrosis-and-ethylene-inducing peptide 1 (Nep1)-like proteins (NLPs), cytolytic toxins produced by some bacterial, fungal and oomycete species, are able to target on lipid membranes by binding eudicot plant-specific sphingolipids (glycosylinositol phosphorylceramide) and form transient small pores, causing membrane leakage and subsequent cell death. NLP-producing phytopathogens are a big threat to agriculture worldwide. However, whether there are R proteins/enzymes that counteract the toxicity of NLPs in plants remains largely unknown. Here we show that cotton produces a peroxisome-localized enzyme lysophospholipase, GhLPL2. Upon Verticillium dahliae attack, GhLPL2 accumulates on the membrane and binds to V. dahliae secreted NLP, VdNLP1, to block its contribution to virulence. A higher level of lysophospholipase in cells is required to neutralize VdNLP1 toxicity and induce immunity-related genes expression, meanwhile maintaining normal growth of cotton plants, revealing the role of GhLPL2 protein in balancing resistance to V. dahliae and growth. Intriguingly, GhLPL2 silencing cotton plants also display high resistance to V. dahliae, but show severe dwarfing phenotype and developmental defects, suggesting GhLPL2 is an essential gene in cotton. GhLPL2 silencing results in lysophosphatidylinositol over-accumulation and decreased glycometabolism, leading to a lack of carbon sources required for plants and pathogens to survive. Furthermore, lysophospholipases from several other crops also interact with VdNLP1, implying that blocking NLP virulence by lysophospholipase may be a common strategy in plants. Our work demonstrates that overexpressing lysophospholipase encoding genes have great potential for breeding crops with high resistance against NLP-producing microbial pathogens.

Amorphous MoOx with High Oxophilicity Interfaced with PtMo Alloy Nanoparticles Boosts Anti-CO Hydrogen Electrocatalysis.

Advancing electrocatalysts for alkaline hydrogen oxidation/evolution reaction (HOR/HER) is essential for anion exchange membrane-based devices. The state-of-the-art Pt-based electrocatalysts for alkaline HOR suffer from low intrinsic activities and severe CO poisoning due to the challenge of simultaneously optimizing surface adsorption toward different adsorbates. Herein, this challenge is overcome by tuning an atomic MoOx layer with high oxophilicity onto PtMo nanoparticles (NPs) with optimized Had , OHad , and COad adsorption for boosting anti-CO-poisoning hydrogen-cycle electrocatalysis in alkaline media. For alkaline HOR, this catalyst exhibits high kinetics and an exchange current density of 3.19 mA µgPt -1 at 50 mV versus reversible hydrogen electrode and 0.83 mA cmPt -2 , 10.3- and 3.8-fold higher than those of commercial Pt/C, respectively. For alkaline HER, it achieves an unprecedented overpotential of 37 mV at 10 mA cm-2 . Experimental and theoretical studies show that the orchestrated electronic and oxophilic regulation of the PtMo/MoOx interface NPs simultaneously optimizes Had and OHad adsorption for boosting alkaline hydrogen electrocatalysis, whereas reactive oxygen from the amorphous MoOx atomic layer lowers the CO oxidation reaction barrier, leading to superior anti-poisoning ability even at 100 ppm CO.

In-situ and amplification-free imaging of hERG ion channels at single-cell level using a unique core-molecule-shell-secondary antibody SERS nanoprobe.

Research on ion channels and their monoclonal antibodies plays a critical role in drug development and disease diagnosis. The current ion channel researches are often not conducted in the microenvironment for cells survival, which restricts the mechanism study of the links between the cell structure and the ion channel function. In this work, we synthesized gold core-4-mercaptobenzonitrile-sliver shell-goat anti-rabbit immunoglobulin G (Au@4-MBN@Ag@IgG) nanoparticles as surface-enhanced Raman scattering (SERS) nanoprobes for investigating the human ether-a-go-go related gene (hERG) potassium ion channel in cell membranes. This is the first attempt to study ion channels using SERS. Due to the unique core-molecule-shell structure and the silver shell of nanoprobes, strong and stable SERS signal was obtained. With the help of antibodies, the Au@4-MBN@Ag@IgG nanoprobes were captured by hERG antibodies and then bonded with hERG ion channels based on the sandwich immune response. The reporter molecule, 4-MBN, displayed a strong and sharp characteristic peak at 2233 cm-1 in the Raman silent region. The intensity of this peak denoted the concentration of antibodies and the expression of ion channel proteins. We successfully applied this amplification-free method for in-situ imaging the distribution of the hERG ion channel on the transfected HEK293 cell surface at the single-cell level. This hERG ion channel profiling strategy promises a maneuverable tool for ion channel research.

DNase inhibits early biofilm formation in Pseudomonas aeruginosa- or Staphylococcus aureus-induced empyema models.

Anti-infection strategies against pleural empyema include the use of antibiotics and drainage treatments, but bacterial eradication rates remain low. A major challenge is the formation of biofilms in the pleural cavity. DNase has antibiofilm efficacy in vitro, and intrapleural therapy with DNase is recommended to treat pleural empyema, but the relevant mechanisms remain limited. Our aim was to investigate whether DNase I inhibit the early biofilm formation in Pseudomonas aeruginosa- or Staphylococcus aureus-induced empyema models. We used various assays, such as crystal violet staining, confocal laser scanning microscopy (CLSM) analysis, peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH), and scanning electron microscopy (SEM) analysis. Our results suggested that DNase I significantly inhibited early biofilm formation in a dose-dependent manner, without affecting the growth of P. aeruginosa or S. aureus in vitro. CLSM analysis confirmed that DNase I decreased the biomass and thickness of both bacterial biofilms. The PNA-FISH and SEM analyses also revealed that DNase I inhibited early (24h) biofilm formation in two empyema models. Thus, the results indicated that DNase inhibited early (24h) biofilm formation in P. aeruginosa- or S. aureus-induced rabbit empyema models and showed its therapeutic potential against empyema biofilms.

Performance investigation of TixNx-1O2MXene (x= 2, 3, 4) as anode materials for Na-ion batteries by first-principles calculation.

The number of MXene layers plays a crucial role in their performance when they are used as anode materials for sodium-ion batteries. Herein, Ti-based nitride MXenes with different layers, TixNx-1O2MXene (x= 2, 3, 4) structures, were constructed to calculate the structural stability of their precursor, electronic properties after etching, and sodium storage behavior compared with the common Ti2CO2and Ti3C2O2MXene. First-principles calculations indicate that nitride MXenes possess a better rate capability than carbide MXenes of the same thickness. Moreover, the barrier for Na diffusion on the Ti2NO2MXene surface (0.114 eV) is lowest. Meanwhile, comparing the properties of three nitride MXenes with different thicknesses, Ti2NO2MXene performs relatively well with a high theoretical capacity with 756 mAh g-1and a lower open circuit voltage of 1.1 V. In conclusion, the performance improvement of nitride MXene is not linear with thickness, because that of Ti3N2O2MXene is relatively weaker. This work lays the foundation for the feasibility of Ti3N2Txexperimental preparation and provides corresponding evidence on the choice of MXene thickness. More attention should be paid to the etching method for Ti2NTxMXene.

Local Coordination Regulation through Tuning Atomic-Scale Cavities of Pd Metallene toward Efficient Oxygen Reduction Electrocatalysis.

Moderate adsorption of oxygenated intermediates takes a significant role in rational design of high-efficiency oxygen reduction reaction (ORR) electrocatalysts. Long-serving as a reliable strategy to tune geometric structure of nanomaterials, defect engineering enjoys the great ability of adjusting the coordination environment of catalytic active sites, which enables dominant regulation of adsorption energy and kinetics of ORR catalysis. However, limited to controllable nanocrystals fabrication, inducing uniformly dispersed high-coordinated defects into ultrathin 2D nanosheets remains challenging. Herein, atomic-scale cavities (ASCs) are proposed as a new kind of high-coordinated active site and successfully introduced into suprathin Pd (111)-exposed metallene. Due to its atomic concave architecture, leading to elevated CN and moderately downshifted d-band center, the as-made Pd metallene with ASCs (c-Pd M) exhibits excellent ORR performance with mass activity of 2.76 A mgPd -1 at 0.9 V versus reversible hydrogen electrode (RHE) and half-wave potential as high as 0.947 V, which is 18.9 (2.7) times higher and 104 (46) mV larger than that of commercial Pt/C (Pd metallene without ASCs). Besides, the durability of c-Pd M exceeds its commercial counterpart with ≈30% loss after 5000 cycles. This work highlights a new-style mentality of designing fancy active sites toward efficient ORR electrocatalysis.

A nanohybrid of Prussian blue supported by boracic acid-modified g-C3N4 for Raman recognition of cell surface sialic acid and photothermal/photodynamic therapy.

Theranostic nanoplatforms with accurate diagnosis and effective therapy show a bright prospect for tumor treatments. Herein, a novel boracic acid-modified graphite carbon nitride and Prussian blue nanohybrid (PB@B-g-C3N4) was developed, which provides sialic acid-targeted Raman recognition and synergistic photothermal/photodynamic therapy in the near-infrared region. Owing to the specific interaction between boracic acid and sialic acid and Raman response at 2157 cm-1 of PB, the nanohybrids exhibit high specificity and Raman sensitivity for detection of the overexpressed sialic acid on tumor cells. Moreover, the photothermal conversion efficiency of PB@B-g-C3N4 is as high as 47.0% with 808 nm laser irradiation due to the enhanced absorbance of PB@B-g-C3N4. PB@B-g-C3N4 also possesses excellent photodynamic activity, which is attributed to the energy transfer of PB (type I) and electron transfer between PB and B-g-C3N4 (type II). This nanotheranostic agent for Raman recognition of cancer markers and synergistic photothermal/photodynamic therapy holds great potential for the development of efficient theranostic nanoplatforms.

Chemical fingerprinting and characterization of spilled oils and burnt soot particles - A case study on the Sanchi oil tanker collision in the East China Sea.

The condensate spill accident from the Sanchi oil tanker collision in the East China Sea is unique in world history. To date, the spilled and burnt amounts of condensate remain unknown. The present study demonstrates the chemical fingerprints of a surrogate condensate (SC) from the same source, and of the carried heavy fuel oil (HFO) of the Sanchi accident. The evaporative features of the condensate are demonstrated by allowing the SC to naturally volatilize in a dark fume hood. In addition, the combustion emission of the SC is characterized by conducting a laboratory-scale combustion experiment. The evaporation experiment suggests that the volatilization process plays a significant role in the weathering of the condensate. The results show that the SC and HFO can be clearly distinguished based on their chemical fingerprints of C27-C35 hopanes and C9-C36 n-alkanes, along with priority polycyclic aromatic hydrocarbons (PAHs) and their alkylated derivatives. The compositional data reveal that the lighter component is predominant in the SC, thereby supporting its high volatility and flammability. The greater amounts of heavier components in the HFO indicate its long-term degradation and potential ecological risks to the environment. Further, the trisnorhopane thermal indicator (Ts/Tm) and C29/C30 ratio of hopanes are validated for identification of the SC and the HFO. More importantly, the changes in the hopane ratios of the soot particles are analyzed for the first time in this study, and the results demonstrate the validity of using hopane ratios to fingerprint the condensate soot particles. The diagnostic ratios of 2-MP/1-MP, 9/4-MP/1-MP, and InP/(InP+BghiP) also show decent performance on source identification after the condensate evaporation and combustion processes.

Judgment of benign and early malignant colorectal tumors from ultrasound images with deep multi-View fusion.

BACKGROUND AND OBJECTIVE: Colorectal cancer (CRC) is currently one of the main cancers world-wide, with a high incidence in the elderly. In the diagnosis of CRC, endorectal ultrasound plays an important role in judging benign and early malignant tumors. However, malignant tumors in the early-stage are not easy to identify visually and experts usually seek help from multi-view images, which increases the workload and also exists a certain probability of misdiagnosis. In recent years, with the widespread use of deep learning methods in the analysis of medical images, it becomes necessary to design an effective computer-aided diagnosis (CAD) system of CRC based on multi-view endorectal ultrasound images. METHOD: In this study, we proposed a CAD system for judging benign and early malignant colorectal tumors, and constructed the first multi-view ultrasound image dataset of CRC to validate our algorithm. Our system is an end-to-end model based on a deep neural network (DNN) which includes a feature extraction module based on dense blocks, a multi-view fusion module, and a Multi-Layer Perception-based classifier. A center loss was used for the first time in CAD tasks, to optimize our model. RESULT: On the constructed dataset, the proposed system surpasses expert diagnosis in accuracy, sensitivity, specificity, and F1-score. Compared with the popular deep classification networks and other CAD methods, the algorithm has reached the best performance. Comparative experiments using different feature extraction methods, different view fusion strategies, and different classifiers verify the effectiveness of each part of the algorithm. CONCLUSION: We propose a CAD system for judging benign and early malignant colorectal tumors based on DNN, which combines information of ultrasound images from different views for comprehension. On the first CRC multi-view ultrasound image dataset which we constructed, our method outperforms expert diagnosis results and all other methods, and the effectiveness of each part of the system has been verified. Our system has application value in future medical practice on early diagnosis of CRC.

In situ monitoring PUVA therapy by using a cell-array chip-based SERS platform.

Psoralen ultraviolet A (PUVA) therapy has thrived as a promising treatment for psoriasis. However, overdose of PUVA treatment will cause side-effects, such as melanoma formation. And these side-effects are often ignored during PUVA therapy. Hence, in situ monitoring therapeutic response of PUVA therapy is important to minimize side-effects. Aberrant expression of tyrosinase (TYR) has been proved to be associated with melanoma, indicating that TYR is a potential target for evaluation of PUVA therapy. Herein, we reported a strategy for in situ monitoring TYR activity during PUVA therapy by using a cell-array chip-based SERS platform. The cell-array chip was used to simulate cell survival environment for cell culture. Capture of single cells and living cell analysis were realized in the isolated microchambers. An enzyme-induced core-shell self-assembly substrate was used to evaluate TYR activity in living cells during PUVA therapy. The gold nanoparticle modified with a SERS reporter, 4-mercaptobenzonitrile (4-MBN), was used as the core. In the presence of oxygen and TYR, hydroxylation of l-tyrosine occurred, leading to the reduction of silver ion on the surface of gold cores. The growth of silver shells was accompanied by the increased SERS intensity of the reporter, which is related directly to TYR activity. The detection limit for TYR activity is 0.45 U/mL. Upregulation of TYR activity was successfully monitored after PUVA therapy. Notably, real-time and in situ information of therapeutic response can be obtained through monitoring PUVA therapy by using a cell-array chip-based SERS platform, which has great potential to guide the clinical application of PUVA therapy.

[Multi-omics analysis of regulating effects of hyperoside on lipid metabolism in high-fat diet mice].

The aim of this study was to explore the regulating effects of hyperoside (Hyp) on lipid metabolism in high-fat diet mice. The high-fat diet mouse model was established by high-fat diet induction. After 5 weeks of Hyp intragastric administration in high-fat diet mice, the serum lipid levels before and after Hyp administration were measured by the corresponding kits. The tissue structure of mouse liver was observed by HE staining before and after Hyp administration. The changes of intestinal flora and transcriptome were measured by Illumina platforms. Liquid chromatography-mass spectrometry (LC-MS) was used to determine non-targeted metabolites. The results showed that Hyp significantly reduced lipid levels in the high-fat diet mice and effectively restored the external morphology and internal structure of liver tissue. Hyp changed the species composition of the intestinal flora in high-fat diet mice, increased the abundance of beneficial flora such as Ruminococcus, and decreased the abundance of harmful flora such as Sutterella. Combined multi-omics analysis revealed that the effect of retinoic acid on lipid metabolism was significant in the high-fat diet mice treated with Hyp, while the increase of retinoic acid content was significantly negatively correlated with the expression of genes such as cyp1a2 and ugt1a6b, positively correlated with AF12 abundance, and significantly negatively correlated with unidentified_Desulfovibrionaceae abundance. These results suggest that Hyp may modulate the abundance of AF12, unidentified_Desulfovibrionaceae and inhibit the expression of genes such as cyp1a2 and ugt1a6b, thus increasing the content of retinoic acid and regulating lipid metabolism in the high-fat diet mice.

Lewis-Acidic PtIr Multipods Enable High-Performance Li-O2 Batteries.

The sluggish oxygen reaction kinetics concomitant with the high overpotentials and parasitic reactions from cathodes and solvents is the major challenge in aprotic lithium-oxygen (Li-O2 ) batteries. Herein, PtIr multipods with a low Lewis acidity of the Pt atoms are reported as an advanced cathode for improving overpotentials and stabilities. DFT calculations disclose that electrons have a strong disposition to transfer from Ir to Pt, since Pt has a higher electronegativity than Ir, resulting in a lower Lewis acidity of the Pt atoms than that on the pure Pt surface. The low Lewis acidity of Pt atoms on the PtIr surface entails a high electron density and a down-shifting of the d-band center, thereby weakening the binding energy towards intermediates (LiO2 ), which is the key in achieving low oxygen-reduction-reaction (ORR) and oxygen-evolution-reaction (OER) overpotentials. The Li-O2 cell based on PtIr electrodes exhibits a very low overall discharge/charge overpotential (0.44 V) and an excellent cycle life (180 cycles), outperforming the bulk of reported noble-metal-based cathodes.

Emerging Dual-Atomic-Site Catalysts for Efficient Energy Catalysis.

Atomically dispersed metal catalysts with well-defined structures have been the research hotspot in heterogeneous catalysis because of their high atomic utilization efficiency, outstanding activity, and selectivity. Dual-atomic-site catalysts (DASCs), as an extension of single-atom catalysts (SACs), have recently drawn surging attention. The DASCs possess higher metal loading, more sophisticated and flexible active sites, offering more chance for achieving better catalytic performance, compared with SACs. In this review, recent advances on how to design new DASCs for enhancing energy catalysis will be highlighted. It will start with the classification of marriage of two kinds of single-atom active sites, homonuclear DASCs and heteronuclear DASCs according to the configuration of active sites. Then, the state-of-the-art characterization techniques for DASCs will be discussed. Different synthetic methods and catalytic applications of the DASCs in various reactions, including oxygen reduction reaction, carbon dioxide reduction reaction, carbon monoxide oxidation reaction, and others will be followed. Finally, the major challenges and perspectives of DASCs will be provided.

Exploring the Potentials of Ti3CiN2-iTx (i = 0, 1, 2)-MXene for Anode Materials of High-Performance Sodium-Ion Batteries.

Two-dimensional (2D) MXenes, including carbides, nitrides, and carbonitrides MXene, have been proved to be a possible candidate as anode materials of sodium-ion batteries. This paper focuses on the electronic properties and the electrochemical performance of nitrides MXene. First, density functional theory simulations were utilized to disclose the geometric structure and electronic properties, Na diffusion path, and storage behaviors of titanium carbonitrides Ti3CNTx, nitrides MXene Ti3N2Tx, and carbides MXene Ti3C2Tx with oxygen terminations, predicting the more excellent performance of Ti3N2O2 than Ti3C2O2. Also, then the structure characterization and electrochemical performance experiments of Ti3C2Tx and Ti3CNTx were conducted to verify the theoretical predictions and test the cycling performances. The superior performance of Ti3N2O2 originates from the stronger connection of O-Ti-N than that of O-Ti-C, resulting in the stackings of Ti3N2O2 being tighter and the interlayer spacings being larger than that of Ti3C2O2, which is advantageous to sodiation and desodiation. The capacity of Ti3CNTx increased again to 145 mAh/g after 35 cycles at a current density of 20 mA/g, which demonstrated a better rate performance than Ti3C2Tx corroborated by the diffusion barriers of the theoretical calculation results. Ti3CNTx exhibits a good cycling performance of 110 mAh/g (≈60% of the initial value) after 200 cycles, which is better than that of 87 mAh/g (≈51% of the initial value) of Ti3C2Tx. It is worth noting that all these performances ensure that nitride MXene is more suitable as the anode material of Na-ion batteries than carbide MXene. These findings are conducive to expanding the MXene family and promoting their application in energy storage applications.