Showing papers in "Chinese Science Bulletin in 2021"

Insights into photoluminescence mechanisms of carbon dots: advances and perspectives

Abstract: Carbon dots (CDs) are potentially useful in many areas such as bioimaging, light-emitting diodes, and sensing because of their excellent optical properties, high biocompatibility, and low toxicity. Knowledge of their photoluminescence (PL) mechanisms, which have been widely studied, is of significance in guiding the synthesis and promoting applications of CDs with tunable PL emissions. However, the intrinsic mechanism of PL emission remains unclear, and a unified mechanism has not been found because of differences in particle structures. This review generalizes the categories of CDs, noting their structural diversity. Three types of PL mechanism pertaining to structural differences are outlined: internal factors dominated emission (including the conjugation effect, the surface state, and the synergistic effect), external factors dominated emission (including the molecular state and the environment effect), and crosslink-enhanced emission. Optical applications of CDs are also briefly mentioned. Finally, the prospects for research into PL mechanisms are discussed, noting the remaining challenges and directions for future work.

Vertically-interlaced NiFeP/MXene electrocatalyst with tunable electronic structure for high-efficiency oxygen evolution reaction

Abstract: Layered double hydroxides (LDHs) with decent oxygen evolution reaction (OER) activity have been extensively studied in the fields of energy storage and conversion. However, their poor conductivity, ease of agglomeration, and low intrinsic activity limit their practical application. To date, improvement of the intrinsic activity and stability of NiFe-LDHs through the introduction of heteroatoms or its combination with other conductive substrates to enhance their water-splitting performance has drawn increasing attention. In this study, vertically interlaced ternary phosphatised nickel/iron hybrids grown on the surface of titanium carbide flakes (NiFeP/MXene) were successfully synthesised through a hydrothermal reaction and phosphating calcination process. The optimised NiFeP/MXene exhibited a low overpotential of 286 mV at 10 mA cm−2 and a Tafel slope of 35 mV dec−1 for the OER, which exceeded the performance of several existing NiFe-based catalysts. NiFeP/MXene was further used as a water-splitting anode in an alkaline electrolyte, exhibiting a cell voltage of only 1.61 V to achieve a current density of 10 mA cm−2. Density functional theory (DFT) calculations revealed that the combination of MXene acting as a conductive substrate and the phosphating process can effectively tune the electronic structure and density of the electrocatalyst surface to promote the energy level of the d-band centre, resulting in an enhanced OER performance. This study provides a valuable guideline for designing high-performance MXene-supported NiFe-based OER catalysts.

Electrolytes enriched by potassium perfluorinated sulfonates for lithium metal batteries

Abstract: Lithium (Li) metal is widely considered as a promising anode for next-generation lithium metal batteries (LMBs) due to its high theoretical capacity and lowest electrochemical potential. However, the uncontrollable formation of Li dendrites has prevented its practical application. Herein, we propose a kind of multi-functional electrolyte additives (potassium perfluorinated sulfonates) from the multi-factor principle for electrolyte additive molecular design (EDMD) view to suppress the Li dendrite growth. The effects of these additives are revealed through experimental results, molecular dynamics simulations and first-principles calculations. Firstly, K+ can form an electrostatic shield on the surface of Li anode to prevent the growth of Li dendrites. Secondly, potassium perfluorinated sulfonates can improve the activity of electrolytes as co-conductive salts, and lower the electro-potential of Li nucleation. Thirdly, perfluorinated sulfonate anions not only can change the Li+ solvation sheath structure to decrease the desolvation energy barrier and increase the ion migration rate, but also can be partly decomposed to form the superior solid electrolyte interphase (SEI). Benefited from the synergistic effects, an outstanding cycle life over 250 h at 1 mA cm−2 is achieved in symmetric Li||Li cells. In particular, potassium perfluorinated sulfonate additives (e.g., potassium perfluorohexyl sulfonate, denoted as K+PFHS) can also contribute to the formation of high-quality cathode electrolyte interphase (CEI). As a result, Li||LiNi0.6Mn0.2Co0.2O2 full cells exhibit significantly enhanced cycling stability. This multi-factor principle for EDMD offers a unique insight on understanding the electrochemical behavior of ion-type electrolyte additives on both the Li metal anode and high-voltage cathode.

Chiral flux phase in the Kagome superconductor AV3Sb5

Abstract: We argue that the topological charge density wave phase in the quasi-2D Kagome superconductor AV3Sb5 is a chiral flux phase. Considering the symmetry of the Kagome lattice, we show that the chiral flux phase has the lowest energy among those states which exhibit 2 × 2 charge orders observed experimentally. This state breaks the time-reversal symmetry and displays anomalous Hall effect. The explicit pattern of the density of state in real space is calculated. These results are supported by recent experiments and suggest that these materials are new platforms to investigate the interplay between topology, superconductivity and electron–electron correlations.

Extremely stable amidoxime functionalized covalent organic frameworks for uranium extraction from seawater with high efficiency and selectivity

Abstract: Uranium extraction from seawater is of strategic significance for nuclear power generation. Amidoxime-based functional adsorbents play indispensable roles in the recovery of seawater uranium with high efficiency. Nevertheless, balancing the adsorption capacity and selectivity is challenging in the presence of complicated interfering ions especially vanadium. Herein, a polyarylether-based covalent organic framework functionalized with open-chain amidoxime (COF-HHTF-AO) was synthesized with remarkable chemical stability and excellent crystallinity. Impressively, the adsorption capacity of COF-HHTF-AO towards uranium in natural seawater reached up to 5.12 mg/g, which is 1.61 times higher than that for vanadium. Detailed computational calculations revealed that the higher selectivity for uranium over vanadium originated from the specific bonding nature and coordination pattern with amidoxime. Combining enhanced adsorption capacity, excellent selectivity and ultrahigh stability, COF-HHTF-AO serves as a promising adsorbent for uranium extraction from the natural seawater.

Cationic intermediates assisted self-assembly two-dimensional Ti3C2T /rGO hybrid nanoflakes for advanced lithium-ion capacitors

Abstract: Two-dimensional (2D) material MXenes have been intensively concerned in energy-storage field due to these unique properties of metallic-like conductivity, good hydrophilicity and high volumetric capacity. However, the self-restocking of ultra-thin 2D materials seriously hinders these performances, which significantly inhibits the full exploitation of MXenes in the field of energy storage. To solve this issue, a strategy to prepare delaminated Ti3C2Tx (MXene) nanoflakes/reduced graphene oxide (rGO) composites is proposed using the electrostatic self-assembly between positively charged Ti3C2Tx with tetrabutylammonium ion (TBA+) modification and negatively charged graphene. The nanoflakes of Ti3C2Tx/rGO are well dispersed and arranged in a face-to-face structure to effectively alleviate the self-restacking and provide more electroactive sites for accessible of electrolyte ions. The prepared delaminated Ti3C2Tx/rGO anode shows a high reversible capacity up to 1394 mAh g−1 at a current density of 50 mA g−1. Moreover, a lithium-ion capacitor (LIC) was assembled with delaminated Ti3C2Tx/rGO anode and activated carbon (AC) cathode which can exhibit a specific capacity of 70.7 F g−1 at a current density of 0.1 A g−1 and deliver an ultrahigh energy density of 114 Wh kg−1 at a relatively high power density of 3125 W kg−1. These good electrochemical performances demonstrate the potential of delaminated Ti3C2Tx/rGO as an anode material for lithium-ion capacitors.

Ultrasensitive strain sensor based on superhydrophobic microcracked conductive Ti3C2Tx MXene/paper for human-motion monitoring and E-skin

Abstract: With the rapid development of wearable intelligent devices, low-cost wearable strain sensors with high sensitivity and low detection limit are urgently demanded. Meanwhile, sensing stability of sensor in wet or corrosive environments should also be considered in practical applications. Here, superhydrophobic microcracked conductive paper-based strain sensor was fabricated by coating conductive Ti3C2Tx MXene on printing paper via dip-coating process and followed by depositing superhydrophobic candle soot layer on its surface. Owing to the ultrasensitive microcrack structure in the conductive coating layer induced by the mismatch of elastic modulus and thermal expansion coefficient between conductive coating layer and paper substrate during the drying process, the prepared paper-based strain sensor exhibited a high sensitivity (gauge factor, GF = 17.4) in the strain range of 0–0.6%, ultralow detection limit (0.1% strain) and good fatigue resistance over 1000 cycles towards bending deformation. Interestingly, it was also applicable for torsion deformation detection, showing excellent torsion angle dependent, repeatable and stable sensing performances. Meanwhile, it displayed brilliant waterproof, self-cleaning and corrosion-resistant properties due to the existence of micro/nano-structured and the low surface energy candle soot layer. As a result, the prepared paper-based strain sensor can effectively monitor a series of large-scale and small-scale human motions even under water environment, showing the great promising in practical harsh outdoor environments. Importantly, it also demonstrated good applicability for spatial strain distribution detection of skin upon body movement when assembled into electronic-skin (E-skin). This study will provide great guidance for the design of next generation wearable strain sensor.

Evidence of a J/psi Lambda structure and observation of excited Xi(-) states in the Xi(-)(b) -> J/psi Lambda K- decay

Abstract: First evidence of a structure in the $J/\psi{\Lambda}$ invariant mass distribution is obtained from an amplitude analysis of$\Xi_b^-{\rightarrow}J/\psi{\Lambda}K^-$ decays. The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of $3.1\sigma$ including systematic uncertainties and look-elsewhere effect. Its mass and width are determined to be $4458.8\pm2.9^{+4.7}_{-1.1}$ MeV and $17.3\pm6.5^{+8.0}_{-5.7}$ MeV, respectively, where the quoted uncertainties are statistical and systematic. The structure is also consistent with being due to two resonances. In addition, the narrow excited $\Xi^-$ states, $\Xi(1690)^-$ and $\Xi(1820)^-$, are seen for the first time in a $\Xi^-_b$ decay, and their masses and widths are measured with improved precision. The analysis is performed using $pp$ collision data corresponding to a total integrated luminosity of 9 fb$^{-1}$, collected with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV.

Perovskite QLED with an external quantum efficiency of over 21% by modulating electronic transport

Abstract: Perovskite quantum-dot-based light-emitting diodes (QLEDs) are highly promising for future solid-state lightings and high-definition displays due to their excellent color purity. However, their device performance is easily affected by charge accumulation induced luminescence quenching due to imbalanced charge injection in the devices. Here we report green perovskite QLEDs with simultaneously improved efficiency and operational lifetime through balancing the charge injection with the employment of a bilayered electron transport structure. The charge-balanced QLEDs exhibit a color-saturated green emission with a full-width at half-maximum (FWHM) of 18 nm and a peak at 520 nm, a low turn-on voltage of 2.0 V and a champion external quantum efficiency (EQE) of 21.63%, representing one of the most efficient perovskite QLEDs so far. In addition, the devices with modulated charge balance demonstrate a nearly 20-fold improvement in the operational lifetime compared to the control device. Our results demonstrate the great potential of further improving the device performance of perovskite QLEDs toward practical applications in lightings and displays via rational device engineering.

Enhancing solar steam generation using a highly thermally conductive evaporator support

Abstract: Interfacial solar steam generation is an efficient water evaporation technology which has promising applications in desalination, sterilization, water purification and treatment. A common component of evaporator design is a thermal-insulation support placed between the photothermal evaporation surface and bulk water. This configuration, common in 2-dimensional (2D) evaporation systems, minimizes heat loss from evaporation surface to bulk water, thus localizing the heat on the evaporation surface for efficient evaporation. This design is subsequently directly adopted for 3-dimensional (3D) evaporators without any consideration if it is appropriate. However, unlike 2D solar evaporators, the 3D evaporators can also harvest additional energy (other than solar light) from the air and bulk water to enhance evaporation rate. In this scenario, the use of thermal insulator support is not proper since it will hinder energy extraction from water. Here, the traditional 3D evaporator configuration was completely redesigned by using a highly thermally conductive material, instead of a thermal insulator, to connect evaporation surfaces and the bulk water. Much higher evaporation rates were achieved by this strategy, owing to the rapid heat transfer from the bulk water to the evaporation surfaces. Indoor and outdoor tests both confirmed that evaporation performance could be significantly improved by substituting a thermal insulator with thermally conductive support. These findings will redirect the future design of 3D photothermal evaporators.

Recent advances in organic electrosynthesis employing transition metal complexes as electrocatalysts

Abstract: Organic electrosynthesis has been widely used as an environmentally conscious alternative to conventional methods for redox reactions because it utilizes electric current as a traceless redox agent instead of chemical redox agents. Indirect electrolysis employing a redox catalyst has received tremendous attention, since it provides various advantages compared to direct electrolysis. With indirect electrolysis, overpotential of electron transfer can be avoided, which is inherently milder, thus wide functional group tolerance can be achieved. Additionally, chemoselectivity, regioselectivity, and stereoselectivity can be tuned by the redox catalysts used in indirect electrolysis. Furthermore, electrode passivation can be avoided by preventing the formation of polymer films on the electrode surface. Common redox catalysts include N-oxyl radicals, hypervalent iodine species, halides, amines, benzoquinones (such as DDQ and tetrachlorobenzoquinone), and transition metals. In recent years, great progress has been made in the field of indirect organic electrosynthesis using transition metals as redox catalysts for reaction classes including C–H functionalization, radical cyclization, and cross-coupling of aryl halides-each owing to the diverse reactivity and accessible oxidation states of transition metals. Although various reviews of organic electrosynthesis are available, there is a lack of articles that focus on recent research progress in the area of indirect electrolysis using transition metals, which is the impetus for this review.

Interface engineering of heterostructured electrocatalysts towards efficient alkaline hydrogen electrocatalysis

Abstract: Boosting the alkaline hydrogen evolution and oxidation reaction (HER/HOR) kinetics is vital to practicing the renewable hydrogen cycle in alkaline media. Recently, intensive research has demonstrated that interface engineering is of critical significance for improving the performance of heterostructured electrocatalysts particularly toward the electrochemical reactions involving multiple reaction intermediates like alkaline hydrogen electrocatalysis, and the research advances also bring substantial non-trivial fundamental insights accordingly. Herein, we review the current status of interface engineering with respect to developing efficient heterostructured electrocatalysts for alkaline HER and HOR. Two major subjects—how interface engineering promotes the reaction kinetics and what fundamental insights interface engineering has brought into alkaline HER and HOR—are discussed. Specifically, heterostructured electrocatalysts with abundant interfaces have shown substantially accelerated alkaline hydrogen electrocatalysis kinetics owing to the synergistic effect from different components, which could balance the adsorption/desorption behaviors of the intermediates at the interfaces. Meanwhile, interface engineering can effectively tune the electronic structures of the active sites via electronic interaction, interfacial bonding, and lattice strain, which would appropriately optimize the binding energy of targeted intermediates like hydrogen. Furthermore, the confinement effect is critical for delivering high durability by sustaining high density of active sites. At last, our own perspectives on the challenges and opportunities toward developing efficient heterostructured electrocatalysts for alkaline hydrogen electrocatalysis are provided.

Engineering two-dimensional metal oxides and chalcogenides for enhanced electro- and photocatalysis

Abstract: Two-dimensional (2D) metal oxides and chalcogenides (MOs & MCs) have been regarded as a new class of promising electro- and photocatalysts for many important chemical reactions such as hydrogen evolution reaction, CO2 reduction reaction and N2 reduction reaction in virtue of their outstanding physicochemical properties However, pristine 2D MOs & MCs generally show the relatively poor catalytic performances due to the low electrical conductivity, few active sites and fast charge recombination Therefore, considerable efforts have been devoted to engineering 2D MOs & MCs by rational structural design and chemical modification to further improve the catalytic activities Herein, we comprehensively review the recent advances for engineering technologies of 2D MOs & MCs, which are mainly focused on the intercalation, doping, defects creation, facet design and compositing with functional materials Meanwhile, the relationship between morphological, physicochemical, electronic, and optical properties of 2D MOs & MCs and their electro- and photocatalytic performances is also systematically discussed Finally, we further give the prospect and challenge of the field and possible future research directions, aiming to inspire more research for achieving high-performance 2D MOs & MCs catalysts in energy storage and conversion fields

Encyclopedia of emergent particles in three-dimensional crystals

Abstract: The past decade has witnessed a surge of interest in exploring emergent particles in condensed matter systems. Novel particles, emerged as excitations around exotic band degeneracy points, continue to be reported in real materials and artificially engineered systems, but so far, we do not have a complete picture on all possible types of particles that can be achieved. Here, via systematic symmetry analysis and modeling, we accomplish a complete list of all possible particles in timereversal-invariant systems. This includes both spinful particles such as electron quasiparticles in solids, and spinless particles such as phonons or even excitations in electric-circuit and mechanical networks. We establish detailed correspondence between the particle, the symmetry condition, the effective model, and the topological character. This obtained encyclopedia concludes the search for novel emergent particles and provides concrete guidance to achieve them in physical systems.

Mapping high resolution National Soil Information Grids of China

Abstract: Soil spatial information has traditionally been presented as polygon maps at coarse scales. Solving global and local issues, including food security, water regulation, land degradation, and climate change requires higher quality, more consistent and detailed soil information. Accurate prediction of soil variation over large and complex areas with limited samples remains a challenge, which is especially significant for China due to its vast land area which contains the most diverse soil landscapes in the world. Here, we integrated predictive soil mapping paradigm with adaptive depth function fitting, state-of-the-art ensemble machine learning and high-resolution soil-forming environment characterization in a high-performance parallel computing environment to generate 90-m resolution national gridded maps of nine soil properties (pH, organic carbon, nitrogen, phosphorus, potassium, cation exchange capacity, bulk density, coarse fragments, and thickness) at multiple depths across China. This was based on approximately 5000 representative soil profiles collected in a recent national soil survey and a suite of detailed covariates to characterize soil-forming environments. The predictive accuracy ranged from very good to moderate (Model Efficiency Coefficients from 0.71 to 0.36) at 0–5 cm. The predictive accuracy for most soil properties declined with depth. Compared with previous soil maps, we achieved significantly more detailed and accurate predictions which could well represent soil variations across the territory and are a significant contribution to the GlobalSoilMap.net project. The relative importance of soil-forming factors in the predictions varied by specific soil property and depth, suggesting the complexity and non-stationarity of comprehensive multi-factor interactions in the process of soil development.

SARS-CoV-2 induced intestinal responses with a biomimetic human gut-on-chip.

Abstract: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a global pandemic. Clinical evidence suggests that the intestine is another high-risk organ for SARS-CoV-2 infection besides the lungs. However, a model that can accurately reflect the response of the human intestine to the virus is still lacking. Here, we created an intestinal infection model on a chip that allows the recapitulation of human relevant intestinal pathophysiology induced by SARS-CoV-2 at organ level. This microengineered gut-on-chip reconstitutes the key features of the intestinal epithelium-vascular endothelium barrier through the three-dimensional (3D) co-culture of human intestinal epithelial, mucin-secreting, and vascular endothelial cells under physiological fluid flow. The intestinal epithelium showed permissiveness for viral infection and obvious morphological changes with injury of intestinal villi, dispersed distribution of mucus-secreting cells, and reduced expression of tight junction (E-cadherin), indicating the destruction of the intestinal barrier integrity caused by virus. Moreover, the vascular endothelium exhibited abnormal cell morphology, with disrupted adherent junctions. Transcriptional analysis revealed abnormal RNA and protein metabolism, as well as activated immune responses in both epithelial and endothelial cells after viral infection (e.g., upregulated cytokine genes), which may contribute to the injury of the intestinal barrier associated with gastrointestinal symptoms. This human organ system can partially mirror intestinal barrier injury and the human response to viral infection, which is not possible in existing in vitro culture models. It provides a unique and rapid platform to accelerate COVID-19 research and develop novel therapies.

Iontronic pressure sensor with high sensitivity and linear response over a wide pressure range based on soft micropillared electrodes

Abstract: Electronic skins and flexible pressure sensors are important devices for advanced healthcare and intelligent robotics. Sensitivity is a key parameter of flexible pressure sensors. Whereas introducing surface microstructures in a capacitive-type sensor can significantly improve its sensitivity, the signal becomes nonlinear and the pressure response range gets much narrower, significantly limiting the applications of flexible pressure sensors. Here, we designed a pressure sensor that utilizes a nanoscale iontronic interface of an ionic gel layer and a micropillared electrode, for highly linear capacitance-to-pressure response and high sensitivity over a wide pressure range. The micropillars undergo three stages of deformation upon loading: initial contact (0–6 kPa) and structure buckling (6–12 kPa) that exhibit a low and nonlinear response, as well as a post-buckling stage that has a high signal linearity with high sensitivity (33.16 kPa−1) over a broad pressure range of 12–176 kPa. The high linearity lies in the subtle balance between the structure compression and mechanical matching of the two materials at the gel-electrode interface. Our sensor has been applied in pulse detection, plantar pressure mapping, and grasp task of an artificial limb. This work provides a physical insight in achieving linear response through the design of appropriate microstructures and selection of materials with suitable modulus in flexible pressure sensors, which are potentially useful in intelligent robots and health monitoring.

Structure development of carbon-based solar-driven water evaporation systems

Abstract: Pressing need goes ahead for accessing freshwater in insufficient supply countries and regions, which will become a restrictive factor for human development and production. In recent years, solar-driven water evaporation (SDWE) systems have attracted increasing attention for their specialty in no consume conventional energy, pollution-free, and the high purity of fresh water. In particular, carbon-based photothermal conversion materials are preferred light-absorbing material for SDWE systems because of their wide range of spectrum absorption and high photothermal conversion efficiency based on super-conjugate effect. Until now, many carbon-based SDWE systems have been reported, and various structures emerged and were designed to enhance light absorption, optimize heat management, and improve the efficient water transport path. In this review, we attempt to give a comprehensive summary and discussions of structure progress of the carbon-based SDWE systems and their working mechanisms, including carbon nanoparticles systems, single-layer photothermal membrane systems, bi-layer structural photothermal systems, porous carbon-based materials systems, and three dimensional (3D) systems. In these systems, the latest 3D systems can expand the light path by allowing light to be reflected multiple times in the microcavity to increase the light absorption rate, and its large heat exchange area can prompt more water to evaporate, which makes them the promising application foreground. We hope our review can spark the probing of underlying principles and inspiring design strategies of these carbon-based SDWE systems, and further guide device optimizations, eventually promoting in extensive practical applications in the future.

Quantum computational advantage via 60-qubit 24-cycle random circuit sampling

Abstract: To ensure a long-term quantum computational advantage, the quantum hardware should be upgraded to withstand the competition of continuously improved classical algorithms and hardwares. Here, we demonstrate a superconducting quantum computing systems Zuchongzhi 2.1, which has 66 qubits in a two-dimensional array in a tunable coupler architecture. The readout fidelity of Zuchongzhi 2.1 is considerably improved to an average of 97.74%. The more powerful quantum processor enables us to achieve larger-scale random quantum circuit sampling, with a system scale of up to 60 qubits and 24 cycles, and fidelity of F XEB = ( 3.66 ± 0.345 ) × 10 - 4 . The achieved sampling task is about 6 orders of magnitude more difficult than that of Sycamore [Nature 574, 505 (2019)] in the classic simulation, and 3 orders of magnitude more difficult than the sampling task on Zuchongzhi 2.0 [arXiv:2106.14734 (2021)]. The time consumption of classically simulating random circuit sampling experiment using state-of-the-art classical algorithm and supercomputer is extended to tens of thousands of years (about 4.8 × 10 4 years), while Zuchongzhi 2.1 only takes about 4.2 h, thereby significantly enhancing the quantum computational advantage.

Perovskite-based tandem solar cells

Abstract: The power conversion efficiency for single-junction solar cells is limited by the Shockley-Quiesser limit. An effective approach to realize high efficiency is to develop multi-junction cells. These years have witnessed the rapid development of organic–inorganic perovskite solar cells. The excellent optoelectronic properties and tunable bandgaps of perovskite materials make them potential candidates for developing tandem solar cells, by combining with silicon, Cu(In,Ga)Se2 and organic solar cells. In this review, we present the recent progress of perovskite-based tandem solar cells, including perovskite/silicon, perovskite/perovskite, perovskite/Cu(In,Ga)Se2, and perovskite/organic cells. Finally, the challenges and opportunities for perovskite-based tandem solar cells are discussed.

Confining ultrafine SnS nanoparticles in hollow multichannel carbon nanofibers for boosting potassium storage properties

Abstract: SnS has been extensively investigated as a potential anode material in potassium-ion batteries (PIBs) for its high theoretical capacity. Nonetheless, it suffers a limited cyclic lifespan owing to its poor electronic conductivity and huge volume expansion. This work proposed a facile approach where SnS nanocrystals are confined in the walls of hollow multichannel carbon nanofibers (denoted SnS@HMCFs) to tackle the issues above. In contrast to previous studies, impregnated ultrafine SnS nanocrystals in HMCFs compactly can increase the SnS loading number per unit area of the carbon matrix. Furthermore, the unique hollow multichannel carbon nanofibers are used as a robust carrier to uniformly distribute the SnS nanocrystals. This can significantly accelerate K+/electron transport, resulting in large specific capacity, outstanding rate performance, and steady cycling property for PIBs. High reversible capacities of 415.5 mAh g−1 at 0.1 A g−1 after 300 cycles and 245.5 mAh g−1 at 1 A g−1 after 1000 cycles are retained, suggesting great potential of SnS@HMCFs as a negative electrode material for PIBs. Additionally, when the SnS@HMCF anode is assembled with the KVPO4F cathode, the obtained full cell shows a large discharge capacity of 165.3 mAh g−1 after 200 cycles at 0.1 A g−1.

Conversion of bimetallic MOF to Ru-doped Cu electrocatalysts for efficient hydrogen evolution in alkaline media

Abstract: The rational design and construction of inexpensive and highly active electrocatalysts for hydrogen evolution reaction (HER) is of great importance for water splitting Herein, we develop a facile approach for preparation of porous carbon-confined Ru-doped Cu nanoparticles (denoted as [email protected]) by direct pyrolysis of the Ru-exchanged Cu-BTC metal–organic framework When served as the electrocatalyst for HER, strikingly, the obtained [email protected] catalyst exhibits an ultralow overpotential (only 20 mV at 10 mA cm−2) with a small Tafel slope of 37 mV dec−1 in alkaline electrolyte The excellent performance is comparable or even superior to that of commercial Pt/C catalyst Density functional theory (DFT) calculations confirm that introducing Ru atoms into Cu nanocrystals can significantly alter the desorption of H2 to achieve a close-to-zero hydrogen adsorption energy and thereby boost the HER process This strategy gives a fresh impetus to explore low-cost and high-performance catalysts for HER in alkaline media

High content anion (S/Se/P) doping assisted by defect engineering with fast charge transfer kinetics for high-performance sodium ion capacitors

Abstract: The rate-determining process for sodium storage in TiO2 is greatly depending on charge transfer happening in the electrode materials owing to its inferior diffusion coefficient and electronic conductivity. Apart from reducing the diffusion distance of ion/electron, the increasement of ionic/electronic mobility in the crystal lattice is also very important for charge transport. Here, an oxygen vacancy (OV) engineering assisted in high-content anion (S/Se/P) doping strategy to enhance charge transfer kinetics for ultrafast sodium-storage performance is proposed. Theoretical calculations indicate that OV-engineering evokes spontaneous S doping into the TiO2 phase and achieves high dopant concentration to bring about impurity state electron donor and electronic delocalization over S occupied sites, which can largely reduce the migration barrier of Na+. To realize the speculation, high-content anion doped anatase TiO2/C composites (9.82 at% for S in A-TiO2–x-S/C) are elaborately designed. The optimized A-TiO2–x-S/C anode exhibits extraordinarily high-rate capability with 209.6 mAh g−1 at 5000 mA g−1. The assembled sodium ion capacitors deliver an ultrahigh energy density of 150.1 Wh kg−1 at a power density of 150 W kg−1 when applied as anode materials. This work provides a new strategy to realize high content anion doping concentration, and enhances the charge transfer kinetics for TiO2, which delivers an efficient approach for the design of electrode materials with fast kinetic.

Triboelectric nanogenerators for human-health care

Abstract: This manuscript summarizes the progress and development status of TENG in health care.Based on the different types of applications subdirection, the TENG-based research work of this field in recent eight years is reviewed. This review is dedicated to provide reference and inspiration for the future development and innovation of TENG for health care.Since the world’s first triboelectric nanogenerator (TENG) was proposed in 2012, numerous TENG-based devices and equipment have sprung up in various fields. In particular, TENG has great potential in the field of human-health care due to its small size, self-powered and low cost. With the continuous deepening of TENG research, its structure, function and technical concept are becoming more and more abundant. In order to summarize the progress and development status of TENG in health care, based on the different types of applications subdirection, this paper reviews the TENG-based research work of this field in recent eight years. The characteristics of various types of TENG-based applications and their corresponding technologies are introduced and analyzed, under the comparison of their structure and performance. This review is dedicated to provide reference and inspiration for the future development and innovation of TENG for health care.

Polypeptide nanoformulation-induced immunogenic cell death and remission of immunosuppression for enhanced chemoimmunotherapy

Abstract: Many conventional chemotherapeutics play an immune-modulating effect by inducing immunogenic cell death (ICD) in tumor cells. However, they hardly arouse strong antitumor immune response because the immunosuppressive lymphocytes are present in the tumor microenvironment. These immunosuppressive lymphocytes include regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs). We used a low dose of doxorubicin (DOX) to induce ICD in combination with immune regulator 1-methyl-DL-tryptophan (1MT) to suppress indoleamine 2,3-dioxygenase and overcome Treg- and MDSC-associated immune suppression. By co-encapsulation of DOX and 1MT into a reduction-responsive polypeptide nanogel, the drugs were simultaneously released in the tumor cells and synergistically performed antitumor efficacy. After treatment, recruitment of Tregs and MDSCs was inhibited, and the frequency of tumor-infiltrating CD8+ T cells was remarkably enhanced. These results demonstrated that the chemoimmunotherapy strategy effectively suppressed tumor growth without causing evident adverse effects, indicating its great potential in clinical cancer therapy.

Holey platinum nanotubes for ethanol electrochemical reforming in aqueous solution

Abstract: The catalytic/electrocatalytic performance of platinum (Pt) nanostructures highly relates to their morphology. Herein, we propose a facile self-template pyrolysis strategy at high temperature to synthesize one-dimensionally holey Pt nanotubes (Pt-hNTs) using PtII-dimethylglyoxime complex (PtII-DMG) nanorods as the reaction precursor. The coordination capability of DMG results in the generation of PtII-DMG nanorods, whereas the reducibility of DMG at high temperature leads to the reduction of PtII species in PtII-DMG nanorods. During the reaction process, the inside-out Ostwald ripening phenomenon leads to the hollow morphology of Pt-hNTs. Benefiting from the physical characteristics of hollow and holey structure, Pt-hNTs with clean surface show superior electroactivity and durability for catalyzing ethanol electrooxidation as well as hydrogen evolution reaction in alkaline media. Under optimized experimental conditions, the constructed symmetric Pt-hNTs||Pt-hNTs ethanol electrolyzer only requires an electrolysis voltage of 0.40 V to achieve the electrochemical hydrogen production, demonstrating a highly energy saving strategy relative to traditional water electrolysis.

SARS-CoV-2 nucleocapsid protein phase separates with G3BPs to disassemble stress granules and facilitate viral production.

Abstract: A key to tackling the coronavirus disease 2019 (COVID-19) pandemic is to understand how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) manages to outsmart host antiviral defense mechanisms. Stress granules (SGs), which are assembled during viral infection and function to sequester host and viral mRNAs and proteins, are part of the antiviral responses. Here, we show that the SARS-CoV-2 nucleocapsid (N) protein, an RNA binding protein essential for viral production, interacted with Ras-GTPase-activating protein SH3-domain-binding protein (G3BP) and disrupted SG assembly, both of which require intrinsically disordered region1 (IDR1) in N protein. The N protein partitioned into SGs through liquid-liquid phase separation with G3BP, and blocked the interaction of G3BP1 with other SG-related proteins. Moreover, the N protein domains important for phase separation with G3BP and SG disassembly were required for SARS-CoV-2 viral production. We propose that N protein-mediated SG disassembly is crucial for SARS-CoV-2 production.

Projection of climate extremes in China, an incremental exercise from CMIP5 to CMIP6

Abstract: This paper presents projections of climate extremes over China under global warming of 1.5, 2, and 3 °C above pre-industrial (1861–1900), based on the latest Coupled Model Intercomparison Project phase 6 (CMIP6) simulations. Results are compared with what produced by the precedent phase of the project, CMIP5. Model evaluation for the reference period (1985–2005) indicates that CMIP6 models outperform their predecessors in CMIP5, especially in simulating precipitation extremes. Areal averages for changes of most indices are found larger in CMIP6 than in CMIP5. The emblematic annual mean temperature, when averaged over the whole of China in CMIP6, increases by 1.49, 2.21, and 3.53 °C (relative to 1985–2005) for 1.5, 2, and 3 °C above-preindustrial global warming levels, while the counterpart in CMIP5 is 1.20, 1.93 and 3.39 °C respectively. Similarly, total precipitation increases by 5.3%, 8.6%, and 16.3% in CMIP6 and by 4.4%, 7.0% and 12.8% in CMIP5, respectively. The spatial distribution of changes for extreme indices is generally consistent in both CMIP5 and CMIP6, but with significantly higher increases in CMIP6 over northeast and northwest China for the hottest day temperature, and south China for the coldest night temperature. In the south bank of the Yangtze River, and most regions around 40°N, CMIP6 shows higher increases for both total precipitation and heavy precipitation. The projected difference between CMIP6 and CMIP5 is mainly attributable to the physical upgrading of climate models and largely independent from their emission scenarios.

Mapping anthropogenic emissions in China at 1 km spatial resolution and its application in air quality modeling

Abstract: New challenges are emerging in fine-scale air quality modeling in China due to a lack of high-resolution emission maps. Currently, only a few emission sources have accurate geographic locations (point sources), while a large part of sources, including industrial plants, are estimated as provincial totals (area sources) and spatially disaggregated onto grid cells based on proxies; this approach is reasonable to some extent but is highly questionable at fine spatial resolutions. Here, we compile a new comprehensive point source database that includes nearly 100,000 industrial facilities in China. We couple it with the frame of Multi-resolution Emission Inventory for China (MEIC), estimate point source emissions, combine point and area sources, and finally map China’s anthropogenic emissions of 2013 at the spatial resolution of 30″×30″ (~1 km). Consequently, the percentages of point source emissions in the total emissions increase from less than 30% in the MEIC up to a maximum of 84% for SO2 in 2013. The new point source-based emission maps show the uncoupled distribution of emissions and populations in space at fine spatial scales, however, such a pattern cannot be reproduced by any spatial proxy used in the conventional emissions mapping. This new accurate high-resolution emission mapping approach reduces the modeled biases of air pollutant concentrations in the densely populated areas compared to the raw MEIC inventory, thus improving the assessment of population exposure.