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Solar photocatalysis is the key to resolve many environmental challenges but is usually hard to achieve over a metal oxide semiconductor. Therefore, assembling π-conjugated molecules onto semiconductors becomes an efficient approach to solar conversion via ligand-to-metal charge transfer. Here, a rational design of ligands for titanium dioxide (TiO2) is presented to produce robust visible light photocatalysts. Three hydroxynaphthoic acids (HNAs) were selected as ligands by extending an extra benzene ring of salicylic acid (SA) at 3,4 or 4,5 or 5,6 positions. These ligands could regulate the performance of TiO2 in which 2-hydroxy-1-naphthoic acid (2H1NA) endows the best outcome. In detail, blue light-powered cooperative photocatalysis of 2H1NA-TiO2 with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO, 5 mol%) inaugurates the expeditious formation of imines by oxidation of amines with atmospheric oxygen (O2). Interestingly, the increase of the O2 pressure from 1 atm to 0.4 MPa promoted the selective oxidation of benzylamine but thereafter declined with a further boost to 0.6 MPa. Notably, an electron transfer between the oxidatively quenched 2H1NA-TiO2 and TEMPO is established, offering a new pathway for environmental applications. This work presents a strategy in designing cutting-edge visible light photocatalysts via altering semiconductors with surface ligands.

Selective sorting of semiconducting single-walled carbon nanotubes (SWNTs) of single chirality is critical for constructing electronic nanodevices with high performance. Nevertheless, trade-off bet...

Oxidative etching possesses an enriched flexibility and atomic-level accuracy in tailoring the size, morphology, surface structure, and composition of colloidal nanocrystals toward their catalytic ...

Nb2O5 is a colourless metal oxide that is very promising in areas such as energy storage and optical glasses. These applications depend on the superior redox properties of Nb2O5 compared to those of other metal oxides, which in turn endow it with great potential in semiconductor photocatalysis. Herein, a hierarchical Nb2O5 was synthesized by the L-arginine-assisted hydrothermal method. Thereafter, visible light photocatalysis was bridged over hierarchical Nb2O5 with a common organic dye, namely alizarin red S (ARS), significantly renovating Nb2O5-based photocatalysis from ultraviolet (UV) into the green light region. The surface of hierarchical Nb2O5 was chemically modified with ARS to harvest 520 nm green light and facilitate the oxidation of organic sulfides with aerial O2. The O-atom transfer from O2 into sulfoxides with very high selectivity occurs via an intermediate of superoxide radical anions (O2˙−). Importantly, the electron transfer from activated ARS to sulfides is mediated by an electron transfer mediator, namely (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), to deter the attack of quenched ARS by reactive oxygen species (ROS). This study represents the first foray of dye-semiconductor assemblies based on a semiconductor other than TiO2 for the selective aerobic oxidation, affirming the generality of cooperative photocatalysis and implying the great potential of hierarchical Nb2O5 in platforming the visible-light-induced selective transformation of organic molecules.

Until now, the green and facile synthesis of highly fluorescent silicon nanoparticles (SiNPs) with robust luminescent stability and favorable biocompatibility for cellular imaging is still a challe...

MnBi2Te4 is an antiferromagnetic topological insulator that has stimulated intense interest due to its exotic quantum phenomena and promising device applications. The surface structure is a determinant factor to understand the magnetic and topological behavior of MnBi2Te4, yet its precise atomic structure remains elusive. Here we discovered a surface collapse and reconstruction of few-layer MnBi2Te4 exfoliated under delicate protection. Instead of the ideal septuple-layer structure in the bulk, the collapsed surface is shown to reconstruct as a Mn-doped Bi2Te3 quintuple layer and a MnxBiyTe double layer with a clear van der Waals gap in between. Combined with first-principles calculations, such surface collapse is attributed to the abundant intrinsic Mn-Bi antisite defects and the tellurium vacancy in the exfoliated surface, which is further supported by in situ annealing and electron irradiation experiments. Our results shed light on the understanding of the intricate surface-bulk correspondence of MnBi2Te4 and provide an insightful perspective on the surface-related quantum measurements in MnBi2Te4 few-layer devices.

A mechanistic understanding of the growth of multiply twinned nanoparticles (MTPs), such as decahedra (Dh) and icosahedra (Ih), is crucial for precisely controlled syntheses and applications. Despite previous successes, no consensus has been reached regarding the multiple competing growth pathways for MTPs proposed thus far, in part due to the lack of information about their nucleation and growth dynamics. Here, we used decahedral and icosahedral gold nanoparticles as a model system in conjunction with in situ liquid cell transmission electron microscopy (LCTEM) to investigate the nucleation and growth dynamics of MTPs in aqueous solution; two growth pathways were successfully identified: (A) nucleation-based layer-by-layer growth from a rounded multiply twinned seed and (B) the successive twinning and growth of tetrahedra. The LCTEM results enabled us to directly and conclusively identify the growth behaviors of intermediate products. The internal strain relaxation mechanisms and growth kinetics differ for the two pathways: in pathway A, a MTP grew by the opening and closing of re-entrant grooves at the twin boundaries, which was not found in pathway B. We also analyzed different MTP growth pathways from an energetic perspective and discussed how the preferred pathway (A or B) is related to factors, such as the initial seed yield and the size- and morphology-dependent formation of MTPs. Our results contextualize the current understanding of MTP formation mechanisms and provide insightful guidance for the precisely controlled synthesis of MTPs for practical applications.

Iridium(III) porphycene complex was synthesized and structurally characterized for the first time. The introduction of the posttransition iridium(III) ion not only significantly enhances the absorption intensity at the end of visible region, but also displays efficient singlet oxygen quantum yield (76%), which is applicable for photodynamic therapy in living cells.

Selective conversion of carbon dioxide (CO2) to a reusable form of carbon via electrochemical reduction has attracted intensive interest for the storage of renewable energy. However, the achievement of efficient bulk monolithic electrocatalysts still remains a challenge. Herein, a facile oxidative etching of the Au20Cu80 alloy was developed for the synthesis of a monolithic nanoporous core–shell structured AuCu3@Au electrode, which showed a faradaic efficiency (FE) of 97.27% with a partial current density of 5.3 mA cm−2 at −0.6 V vs. RHE for the production of CO. The FE value is about 1.45 times higher than that over the Au nanocatalyst. Unlike single nanoporous Au, AuCu3@Au maintained an excellent performance in a broad potential window. Furthermore, a 23 cm long nanoporous AuCu3@Au bulk electrode with good ductility was prepared, over which the active current reached up to 37.2 mA with a current density of 10.78 mA cm−2 at −0.7 V vs. RHE, pushing the reduction of CO2 to industrialization. The unsaturated coordination environment with a coordination number of 8.2 over the shell gold and curved interface determined this high electrocatalytic performance. Density functional theory calculations suggested that the double-dentate adsorption structure in the AuCu3@Au catalyst effectively improves the stability of the *COOH intermediate. The density of states indicates that the introduction of Cu causes the d-band-centre of AuCu3@Au to move toward the Fermi level, directly bonding with *COOH. Therefore, the adsorption of *COOH on the surface of the AuCu3@Au catalyst is strengthened, facilitating the formation of CO. This work opens an avenue to achieve self-supported porous electrodes for various useful catalytic conversions.

An AIEgen decorated porphyrin (TPETPyP) was easily obtained through a one-step reaction. The bulky TPE in TPETPyP greatly impeded the intermolecular π-π stacking of the porphyrin core, which significantly suppressed aggregation-caused quenching (ACQ) effect of TPETPyP in aqueous solution. The four pyridinium salts formed in TPETPyP also render the whole molecule water solubility, which eliminated its aggregation. TPETPyP exhibited 1O2 quantum yield as high as 0.85 in PBS. Moreover, it also showed high binding affinity to proteins, the major biotarget of 1O2. The high 1O2 quantum yield plus the great binding ability of TPETPyP toward proteins makes it a highly-efficient protein photocleaving agent. Protein electrophoresis experiments demonstrated that TPETPyP can photocleave BSA upon visible light irradiation, indicating that TPETPyP can act as a promising photosensitizer (PS) in PDT. The work here will provide a facile strategy to utilize AIEgens modified traditional PSs for photodynamic therapy (PDT).

In this work, Bi2S3/BiOBr hybrid structure has been prepared via ion exchange method. The hybrid structure has enhanced light harvesting ability and improved transfer efficiency of photogenerated carriers thanks to the narrow bandgap of Bi2S3 and staggered band structure of Bi2S3/BiOBr hybrid structure. As a result, Bi2S3/BiOBr hybrid structure exhibits improved photocatalytic N2 fixation performance compared with BiOBr and excellent stability after 4 cycles of photocatalytic nitrogen fixation under visible light irradiation.

The crystallographic shapes of nanocrystals play critical roles in determining their physical and chemical properties. Liquid phase synthesis serves as one of the most important approaches for preparing shape-controlled nanocrystals, therefore, understanding the formation mechanisms of the thermodynamic equilibrium structures of nanocrystals in liquid solution is important. Using in situ liquid cell transmission electron microscopy (TEM), we observe for the first time the shape transformation of individual palladium nanocrystals from energy unfavored spherical shapes into equilibrium truncated octahedrons in aqueous solution. Via quantitative analysis of the shape evolution dynamics of an individual Pd nanocrystal, we find that about 10% of nanocrystal atoms were relocated during the shape transformation. The mass transport is attributed to the synergetic effect of electron beam irradiation and water environment.

In this work, we reported the synthesis of two-dimensional spinel structure of ultrathin Co2AlO4 nanosheets via dealloying and subsequent annealing processes. Oxygen vacancy defects were further introduced into Co2AlO4 nanosheets by a mild solvothermal reduction method, resulting in large electrochemical surface area and high active site densities, making the related Co atoms get electrons, and producing more empty orbitals. The positive charge of Co and Al atoms adjacent to the O vacancies in VO-rich Co2AlO4 reduced significantly, that is, more electrons are concentrated on the Co and Al atoms. Those electrons closed to the Fermi level have a promoting effect during the H2O activation. As a result, the obtained ultrathin Co2AlO4 nanosheets with oxygen vacancies show a low overpotential of 280 mV at the current density of 10 mA cm−2 and a small Tafel slope of 70.98 mV dec−1. Moreover, it also displays a remarkable stability in alkaline solution, which is superior to most of the reported Co3O4 electrocatalysts. The present work paves a new way to achieve efficient new energetic materials for sustainable community.

Thermometers, one of the most commonly used instruments at home, are normally adapted to measure temperature directly with high accuracy but rarely adopted to act as readout in the biosensors. It is necessary to find some ways to establish a relationship between the concentration of the target and the temperature change. In this study, a common thermometer was used as readout to develop a convenient immunosensor. The designed immunosensor comprises three components, including target recognition area, water flow system, and exothermic reaction bottle. The capture antibody for the target [carcinoembryonic antigen (CEA) was selected as a model target] was preloaded on the bottom of the recognition area. In the presence of CEA, a sandwich-type structure was formed between the capture antibody, CEA, and biotinylated detection antibody. Then, the streptavidin-functionalized platinum nanoparticles were labeled on the detection antibody due to biotin-avidin interaction. The captured platinum nanoparticles can effectively catalyze the decomposition of H2O2 into O2. The continuous production of gas resulted in pressure increment inside the reaction bottle and further pushed the water flow into the exothermic reaction bottle. Finally, the water reacted with calcium oxide to generate a large amount of heat in the exothermic reaction bottle; thereby the temperature inside the bottle was enhanced and recorded by a common thermometer easily. The temperature enhancement has a linear relationship with the CEA concentration in the range of 7.81-500 pg/mL with a detection limit of 0.6 pg/mL. Furthermore, by taking advantage of simplicity, compatibility, stability, and high sensitivity, our temperature-based immunoassay has been applied to detect CEA in human serum samples with satisfactory results.

Bi2S3/2D-Bi2WO6 composite materials which combined 2D-Bi2WO6 with Bi2S3 nanoparticles were prepared via ion exchange method. The mass ratio of Bi2S3 nanoparticle could be modulated by changing the quantity of thioacetamide (TAA). For Bi2S3/2D-Bi2WO6 composite materials, Bi2S3 nanoparticles dispersed on the surface of Bi2WO6 nanosheets. The photocatalytic activity was evaluated by photodegradation rhodamine B (RhB) under visible light. RhB was photodegraded nearly completely by BWS-2, while only 67% was photodegraded by Bi2WO6 nanosheet after 5 h' visible light irradiation. Based on the optical and electrochemical measurements, Bi2S3/2D-Bi2WO6 composite materials have prolonged carriers' lifetime, improved carriers' separation efficiency and decreased carriers' recombination efficiency. These results endow Bi2S3/2D-Bi2WO6 composite materials with high photocatalytic activities.

The application of nanoscale zero-valent iron (nZVI) for the degradation of contaminants has been extensively investigated, however, few studies have focused on degradation in high salinity environments. In this study, the ability of bare and carboxymethyl cellulose (CMC)-coated bimetallic Pd-nZVI particles to degrade 33′44′-tetrachlorobiphenyl in high saline water (SW) is examined with particular attention given to the effects of ethylenediaminetetraacetic acid (EDTA) on the rate of degradation. EDTA enhances the reactivity of Pd-nZVI in SW, with evidence provided to link this to the removal of the passivating layer. Additionally, a conceptual model is proposed which provides a quantitative description of the removal of these iron oxide layers in the presence of EDTA. An optimum EDTA to bare Pd-nZVI molar ratio of 0.1 exists, with insufficient EDTA unable to remove the passivating layer whilst excess EDTA results in Fe loss and enhanced agglomeration due to magnetic attraction of the bare Fe(0) particles. In contrast, CMC-coating of Pd-nZVI assemblages actually impedes degradation, despite the coated particles displaying a smaller average size compared to uncoated particles, with even the presence of EDTA in this case not significantly improving degradation. The reduced reactivity in the presence of CMC is primarily attributed to the effect of CMC on the association of Pd with nZVI particles. In particular, the presence of CMC reduced the total amount of Pd incorporated with the stabilized particles compared to the non-stabilized particles. Additionally, the presence of CMC results in less Pd present in its reactive zero-valent oxidation state.

Trifunctional catalysts show a great potential for use in a power-to-gas water-splitting devices for hydrogen gas production, powered by an integrated rechargeable zinc-air battery. None of the currently available commercial electrocatalysts is low cost, and they do not possess excellent catalytic activity and durability at the same time, which is the main barrier to the broad implementation of these technologies. Herein, we design and develop a novel nanostructured trifunctional electrocatalyst that is capable of catalyzing oxygen/hydrogen evolution and oxygen reduction reactions. The combination of non-precious Co, Co9S8, and S, N co-doped graphitic carbon synergistically provides highly active sites for efficient catalytic reactions, while the unique tubular morphology and hierarchically porous microstructure not only benefit fast access to active sites but also ensure a robust composite structure for durability. When applied to zinc-air batteries and water splitting, these systems exhibit performance superior to those of commercial precious electrocatalysts (e.g., Pt/C and Ir/C).

A [4 + 2] annulation involving cascade Knoevenagel, aza-Wittig and dehydrofluorination reactions is developed for the synthesis of substituted quinolin-4-ols including analogs bearing CF2H, CF3, and C2F5 groups. This simple and highly efficient method is also applicable for the synthesis of substituted quinolines. A number of reported biologically active compounds can be readily prepared by this one-pot synthesis. Green chemistry metrics analysis of the new reaction processes provided favorable results.

Sulfidation of silver nanoparticles (Ag-NPs) readily occurs in both urban sewage systems and sulfur-rich natural environments with formation of silver sulfide nanoparticles (Ag2S-NPs). It is essential to understand the transformation and fate of Ag2S-NPs in order to fully evaluate environmental impact of Ag-NPs. The review focuses on the formation and transformation of Ag2S-NPs from both thermodynamic and kinetic perspectives, particularly (i) the formation mechanism of Ag2S in various environmental scenarios, (ii) redox transformation of Ag2S caused by oxidation of S(−II) and (iii) effects of environmental matrices on the formation and transformation processes. In most cases, sulfidation of Ag-NPs causes a dramatic decrease in their toxicity due to the extremely low solubility of Ag2S, potentially restraining their short-term environmental impact. However, the transformation of Ag2S-NPs with potential release of Ag+ and in situ formation of Ag0 and Ag0/Ag2S-NPs hetero-nanostructures may possibly increase the toxicity. Mechanistically-based kinetic modeling has been proposed here to quantitatively describe the rate and extent of the transformation of Ag2S-NPs, with such models of value, at least, in validating proposed transformation mechanisms of Ag2S-NPs and, at best, in predicting their transformation behaviors under realistic environmental conditions.

A new synthetic method for diastereoselective synthesis of tetrahydro-pyrrolo[1,2-d][1,4]benzodiazepines and tetrahydro-pyrrolo[1,2-d][1,4]diazepinones is developed which involves 1,3-dipolar cycloaddition, N-alkylation or N-acylation and Staudinger/aza-Wittig reactions. This one-pot and three-step synthesis of four components gave two different heterocyclic scaffolds. Green chemistry metrics analysis of the reaction process provided favorable results.

Hierarchical ellipsoid-shaped TiO2 porous nanostructures with a high specific surface area and abundant pores are fabricated by the hierarchical assembly of TiO2 nanoparticles via a simple one-pot hydrothermal process. The as-synthesized ellipsoid-shaped TiO2 exhibits significantly enhanced photocatalytic activity for MB degradation compared to P25 under ultraviolet light and sunlight irradiation, respectively.

Multicomponent reactions (MCRs) involving a minimum of three reactants or reaction centers are conducted in one pot and with a single operational step. This synthetic method has a good pot, atom and step economy in the preparation of diverse and complex molecular scaffolds. Consecutive MCRs, also known as sequential or multiple MCRs, by combining two or more MCRs, exhibit even higher synthetic efficiency, product structural diversity, and molecular complexity. This review article highlights the Ugi, Groebke-Blackburn-Bienaymé, Biginelli, Huisgen, Petasis, Gewald, and Asinger reaction-initiated consecutive MCRs.

Multicomponent reactions (MCRs) have inherent advantages in pot, atom, and step economy (PASE). This important green synthetic approach has gained increasing attention due to high efficiency, minimal waste, saving resources, and straightforward procedures. Presented in this review article are the recent development on 5-compoment reactions (5CRs) of the following six types: (I) five different molecules A + B + C + D + E; pseudo-5CRs including (II) 2A + B + C + D, (III) 2A + 2B + C, (IV) 3A + B + C, (V) 3A + 2B, and (VI) 4A + B. 5CRs with more than five-reaction centers are also included.

Layered honeycomb lattice antiferromagnetic $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Ru}{\mathrm{Cl}}_{3}$ has been studied intensively recently as a Kitaev spin liquid candidate. Here we present strong evidence that this material host realistic Weyl fermions derived from Cl $2p$ electrons. Our theoretical analysis suggests the existence of quadratic Weyl fermions without spin-orbit coupling and linear Weyl fermion with spin-orbit coupling. Angle-resolved photoemission spectroscopy with systematic photon energy-dependent measurements demonstrates that this Weyl cone possesses linear dispersion at bulk Brillouin zone center along all the three reciprocal directions and hyperbolic dispersion off center. Our work reveals the rich topological physics lying in the band structure of Kitaev QSL candidates and will stimulate further investigation not only limited to $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Ru}{\mathrm{Cl}}_{3}$ but also honeycomb iridate family of materials.

Here, a fully integrated multicolor immunosensor was developed for sensitive and reliable semiquantitative analysis of HIV-1 p24, which integrates the multistep reactions of horseradish peroxidase (HRP)-linked immunoassay and gold nanorod (AuNR)-based multicolor assay into a single microfluidic chip. The HRP-linked immunoassay functions by moving magnetic beads bound to a capture antibody through different aqueous phases containing immunoassay reagents. HRP-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) is used to mediate AuNRs etching for producing various color changes. Multiple etching processes can be activated by simple mixing of the reagents from the reagent storage reservoir. The fully integrated strategy with sample-in answer-out capability is initiated by simple chip manipulation and finally concluded by converting recognition of antigen-antibody into a vivid color variation for direct visualization and semiquantitative analysis. By bare eye observation, our integrated multicolor immunosensor allows sensitive and reliable semiquantitative analysis of HIV-1 p24 within 1 h. The microfluidic chip device demonstrated here simplifies the operation significantly and thus allows broader application of a multicolor immunosensor for point of care (POC) testing in low-resource settings.

A three-dimensional notched-elliptical microdisk with a wavelength-size notch on the boundary is proposed as a multi-wavelength and unidirectional emission lasing source. The device contains multiple properly designed two-dimensional whispering gallery mode-based polymer notched microdisks with different dimensions for use as a multi-wavelength source. It can have a relatively high optical quality factor of 4000, unidirectional emission with low far-field divergence ∼4°, and the efficiency of emission is as high as 84.2%. The effect of the notch size on the far-field divergence is analyzed, and the multi-wavelength lasing performance is characterized, demonstrating that the resonator is robust and reliable. This work paves a unique but generic way for the design of compact multi-wavelength microlasers.

Experiments reveal that unusual surface behavior at the terminations of a recently discovered magnetic topological insulator depends on the interplay between different building blocks within the material.

As electric vehicles (EVs) have been widely discussed as a promising way to mitigate the effect of climate change, various policies have been implemented across the world to promote the uptake of EVs. Policymakers also paid attention to the density of public charging points. In this paper, we examined the impact of policies on EV markets in the post subsidy era with multiple linear regression analysis using panel data on 13 countries from 2015 to 2018. Five of the independent variables showed significantly positive effects on the 1% level in different regression models: fast/slow charger density, mandate, purchasing restriction and waiver. Subsidies showed significance only on 5% level for battery electric vehicles (BEVs). Financial stimulates have experienced a declining marginal effect, whereas a high density of fast chargers has the most significantly positive effect on EV uptake. This paper suggests policymakers can invest more in completing the public infrastructures of EVs, especially on fast charging points.

The North China Grid has the highest proportion of fossil fuel-based electricity generation in China and also suffers from severe water scarcity issues. This study uses a multi-objective optimization model to explore future configurations of generating and cooling technologies of the electric power sector in the North China Grid subject to constraints imposed by existing policies on water conservation and carbon reduction in 2030. Our findings highlight that the current carbon reduction commitments of China do not have significant impacts on the North China Grid's electric power sector development while policies in the water sector generate much larger impacts. Imposing water constraint according to the ‘Three Red Line’ Policy requires increasing utilization of wind power and air cooling systems, which simultaneously increases economic cost and carbon emissions compared to the business as usual scenario. Imposing enhanced carbon emission and water consumption constraints reap the co-benefits of carbon reduction and water conservation by increasing the proportion of solar PV generation to 8.21%, which increases the unit electricity cost from RMB 0.82 per kWh to RMB 1.37 per kWh. In 2030, electricity generation in the North China Grid generates 1599.88 to 1690.89 million tons (Mt) of carbon emissions under different scenarios whereas imposing water constraint reduces water consumption from 3.34 billion m3 to 1.94 billion m3.

Electric vehicles (EVs) are promoted in recent years as an effective way in alleviating the air pollution caused by tailpipe emissions. However, the pollutants derived from EVs are unheeded. EVs rely on electricity to provide power, and thus their related pollution is transferred to the power plants, which gives rise to the environmental and health pressure to the adjacent regions. In this paper, the transfer of EV-attributed PM2.5, SO2, and NOx inhalations in China are studied. Then by comparing the inhalations versus traffic accessibility among the impacted municipalities, this study sheds light on the environmental injustice lying in the mismatch between pollutant inhalations and traffic accessibility. The results reveal that compared with Shanghai and Shenzhen, the promotion of EVs in Beijing triggers higher pollutant inhalations to its surrounding municipalities. North China Power Grid undertakes 715.62 g PM2.5 inhalation in total, which is 2.51 and 3.20 times higher than the East China Power Grid and the China Southern Power Grid, respectively. The number of municipalities with lower traffic accessibility while higher pollutant inhalation is 8,8, and 17 in North China Power Grid, East China Power Grid, and China Southern Power Grid respectively, indicating conspicuous environmental injustice resulted from the promotion of EVs.

Recently, the layered transition metal dichalcogenide 1T′-MoTe2 has generated considerable interest due to their superconducting and non-trivial topological properties. Here, we present a systematic study on 1T′-MoTe2 single-crystal and exfoliated thin-flakes by means of electrical transport, scanning tunnelling microscope (STM) measurements and band structure calculations. For a bulk sample, it exhibits large magneto-resistance (MR) and Shubnikov–de Hass oscillations in ρxx and a series of Hall plateaus in ρxy at low temperatures. Meanwhile, the MoTe2 thin films were intensively investigated with thickness dependence. For samples, without encapsulation, an apparent transition from the intrinsic metallic to insulating state is observed by reducing thickness. In such thin films, we also observed a suppression of the MR and weak anti-localization (WAL) effects. We attributed these effects to disorders originated from the extrinsic surface chemical reaction, which is consistent with the density functional theory (DFT) calculations and in-situ STM results. In contrast to samples without encapsulated protection, we discovered an interesting superconducting transition for those samples with hexagonal Boron Nitride (h-BN) film protection. Our results indicate that the metallic or superconducting behavior is its intrinsic state, and the insulating behavior is likely caused by surface oxidation in few layer 1T’-MoTe2 flakes.

Sequential inter- and intramolecular [3 + 2] cycloadditions of azomethine ylides are developed for the one-pot and diastereoselective synthesis of highly condensed heterocyclic systems containing pyrrolidine and up to seven stereocenters. It has high synthetic efficiency and operational simplicity, and only water was generated as a byproduct.

The layered MnBi2nTe3n+1 family represents the first intrinsic antiferromagnetic topological insulator (AFM TI, protected by a combination symmetry ) ever discovered, providing an ideal platform to explore novel physics such as quantum anomalous Hall effect at elevated temperature and axion electrodynamics. Recent angle-resolved photoemission spectroscopy (ARPES) experiments on this family have revealed that all terminations exhibit (nearly) gapless topological surface states (TSSs) within the AFM state, violating the definition of the AFM TI, as the surfaces being studied should be -breaking and opening a gap. Here we explain this curious paradox using a surface-bulk band hybridization picture. Combining ARPES and first-principles calculations, we prove that only an apparent gap is opened by hybridization between TSSs and bulk bands. The observed (nearly) gapless features are consistently reproduced by tight-binding simulations where TSSs are coupled to a Rashba-split bulk band. The Dirac-cone-like spectral features are actually of bulk origin, thus not sensitive to the-breaking at the AFM surfaces. This picture explains the (nearly) gapless behaviour found in both Bi2Te3- and MnBi2Te4-terminated surfaces and is applicable to all terminations of MnBi2nTe3n+1 family. Our findings highlight the role of band hybridization, superior to magnetism in this case, in shaping the general surface band structure in magnetic topological materials for the first time., 18 pages, 4 figures

A miniature resonator sensor based on a hybrid plasmonic nanoring with a gold layer coated uniformly on the outer boundary is described and investigated. By using the Lumerical finite-difference-time-domain (FDTD) method, the optimized sizes of the plasmonic layer thickness and the central hole are given and insight into the dependence of spectral displacements, Q factors, sensitivity and detection limits on the ambient refractive index is presented. Simulation results reveal that the miniature resonator sensor featuring high sensitivity of 339.8 nm/RIU can be realized. The highest Q factor can reach ∼60,000 with this nanoring and the minimum detection limit is as low as 1.5 × 10−4 RIU. The effects on the resonance shifts and Q factors due to geometric shapes of the inner boundary of the nanoring are discussed as well. This miniature resonator sensor has good potential for highly sensitive ultracompact sensing applications.

Manufacturing is the foundation of China's economy and accounts for a large proportion of China's CO2 emissions. In this study, the structural path decomposition (SPD) methodology, based on an environmental input-output model, was used to find critical supply chain paths that drive changes in CO2 life cycle in China's manufacturing industry from 1992 to 2012. The changes in CO2 emissions were decomposed into three main factors: carbon emissions intensity, input-output structure, and final demand. In this study, the “weighted average decompositions” method of structural decomposition analysis and the non-comparable input-output table were first applied to the SPD method to obtain accurate results. The results indicate that higher-order paths, especially the paths that started from the “Smelting and Rolling of Metals” and the “Production and Supply of Electricity and Steam” sectors, led to an increase in carbon emissions. This was mainly due to the extension of the industrial chain as well as policy priorities. Moreover, CO2 emissions from the “Chemical Industry”, “Manufacture of Nonmetallic Mineral Products”, and “Smelting and Rolling of Metals” sectors were mainly induced by the increase of final export demands. Based on the results of this study, relevant policy changes have also been recommended.

A unique mineralized cell-based functional platform with biogenic intracellular hydroxyapatite nanoscaffolds (nHAP@yeasts) has been intelligently constructed using a biomimetic mineralization approach. Such a platform not only preserves the nature and functions of cells but also possesses intracellular nanoscaffolds, which endow the mineralized cells with novel functions in biological and nanotechnological applications. Benefiting from their unique organism shell and inorganic core, the nHAP@yeasts are biocompatible and have a large loading capacity for drugs. Such anaerobic microorganisms could be beneficial as drug carriers for the effective delivery and release of loaded drugs in tumors because they prefer to locate and grow in reduced oxygen surroundings. A functional investigation indicated that the nHAP@yeasts, functionalized with folic acid (nHAP@yeasts-FA) as cell-based carriers, showed dual responsive release profiles based on the FA dependency of tumors and the pH-sensitivity of the HAP nanoparticles, and they significantly inhibited tumor growth while displaying low toxicity. This study for the first time provides a bio-friendly strategy to biosynthesize a mineralized cell-based functional platform with biogenic intracellular nanominerals (carbonate, sulfides, selenides, metals, etc.) for biological and nanotechnological application.

Visible light photocatalysis could offer an eco-friendly alternative for selective transformation of organic molecules. Herein, a cooperative system is created with alizarin red S (ARS), TiO2 nanotubes (TNTs), and an extra redox mediator. The electron transfer between oxidatively quenched ARS-TNTs and the redox mediator is the key to secure cooperative photocatalysis. The selective aerobic oxidation of primary and secondary amines was constructed by cooperative photocatalysis of ARS-TNTs with 2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (TEMPO+BF4−) driven by green light. Specifically, the activity of anatase TNTs could reach about 2.2 times that of the P25 (Aeroxide P25) TiO2 precursor. Due to increased polarity, TEMPO+BF4− serves more efficiently for electron transfer than (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO), conferring above 1.5 times of activity that of TEMPO for the selective aerobic conversion of amines. This work features the potential of designing redox mediators in amplifying cooperative photocatalysis driven by visible light.

The nitrogen self-doped porous carbons (NPCs) were prepared using alfalfa as raw material by pyrolysis method without additional nitrogen sources at various pyrolysis temperatures. The NPC supported CuFeO2 (CuFeO2/NPC) composites with large BET surface area (113.18 - 517.56 m2 g−1) were successfully prepared by hydrothermal method without reductant. The NPC prepared at 600 °C (NPC-600) supported CuFeO2 (CuFeO2/NPC-600) possessed the highest catalytic performance for activating peroxydisulfate (PDS) to degrade nimesulide compared to other CuFeO2/NPC composites. The OH, SO4 - and 1O2 were the main reactive species for nimesulide degradation. The oxygen-containing functional groups, pyridinic N, graphitic N, and Fe3+/Fe2+ and Cu2+/Cu+ redox cycles were demonstrated to be extremely important in activating PDS to produce reactive species. The degradation pathway of nimesulide was proposed combined with the HPLC/MS spectra and DFT calculation, and the overall toxicity of nimesulide were effectively alleviated in CuFeO2/NPC-600+PDS system according to toxicity prediction.

Multi-shelled nanomaterials, especially with hierarchically porous structures, are very promising for a variety of potential applications. Herein, the multi-shelled hollow La2O3 nanospheres (MHLN) with high specific surface areas and numerous active sites are first fabricated via a facile and universal synthetic strategy characterized by step-by-step thermal removal of templates. The shell numbers can be easily controlled by adjusting the precursor amount adsorbed into the template. The formation mechanism of the MHLN reveals that the hierarchical assembly of the La2O3 nanoparticles generates the smaller mesoporous of the shells, which providing a complicated but ordered three dimensional network for the MHLN. Notably, the combination of the multi-shelled hollow structure and the special hierarchical pores endows La2O3 nanospheres not only with a large specific surface area but also with good porosity and permeability. Further functional investigation shows that MHLN exhibit a higher removal capacity (192.68 mg P g−1) for phosphate than the reported previously, a fast sorption and exhibit a good stability in wide pH range and excellent reusability.

We introduce a real-time quantitative analytical method for universal silver ions (Ag(I)) and silver nanoparticles (AgNPs) analysis based on a portable nanozyme catalysis-powered portable mini-drainage device. The device is composed of three main glass containers with different specifications. The catalase mimic of ascorbic acid-coated platinum nanoparticles (AA-PtNPs) was used to provide the pumping power to drain water by catalyzing a gas-generation reaction, and the inhibition effect of Ag(I) on the catalytic activity of AA-PtNPs is adopted to connect the target detection event with the mini-drainage device. Experimental results reveal that the mass of the overflowed water is inversely proportional to the concentration of Ag(I) and AgNPs so that their quantitation can be accomplished via real-time weighing of the overflowed water. The importance is that without requiring advanced instruments, this device can quantify Ag(I) and AgNPs with a limit of detection (LOD) of 2.0 nM for Ag(I), and 3.8 pM for AgNPs within 30 min, respectively. The reliability and accuracy are comparable with the inductively coupled plasma optical emission spectrometer (ICP-OES). All these appealing features provide us a remarkable insight into the design of versatile portable devices with potential applications in in-situ environmental monitoring under remote areas and resource-limited settings.

The fast recombination of photogenerated charges, low utilization of visible light and difficult recyclability of photocatalysts limit the practical application of photocatalysis technology. Therefore, ternary reduced graphene oxide/BiOBr/TiO2 nanotube arrays (GB/TNAs) photoelectrodes were prepared for the photoelectrocatalytic (PEC) degradation of p-chloronitrobenzene (p-CNB) under visible light irradiation. The internal interaction among different semiconductors demonstrated that the successful fabrication of ternary heterojunction. The photoelectrochemical properties showed that GB/TNAs exhibited higher visible-light absorption property and lower charges recombination than bare TNAs. The p-CNB degradation rate by GB/TNAs reached 0.0055 min−1, which was 3.93 times than that by TNAs (0.0014 min−1). The GB/TNAs effectively solved the recovery of powdered catalysts, and had excellent PEC stability for p-CNB. The coexistence of dissolved anions and humic acid could decline the p-CNB degradation owing to the competition for active sites or behave as the active radical scavengers. The radical quenching experiments and electron spin resonance spectra revealed that the hydroxyl radical and photogenerated holes were the main active species responsible for the degradation, dechlorination and mineralization of p-CNB. The as-prepared GB/TNAs photoelectrodes display a great potential for the degradation of emerging organic contaminants in wastewater.

Fish product is one of the main seafood with the disadvantage of easy to perish. Various indexes and diverse methods have been developed to evaluate the fish freshness, but most of them are complex and cannot be applied for on-field detection. In this study, we reported a simple, visual and economical multicolor biosensor based on the etching of gold nanorods (GNRs) to evaluate the fish freshness with the naked eye. Hypoxanthine (Hx) is chosen as the index of fish freshness and it react with the dissolved oxygen to produce H 2 O 2 at the presence of xanthine oxidase (XOD). Then GNRs are etched quickly by the H 2 O 2 in the presence of Fe 2+ . Correspondingly, the GNRs surface plasmon resonance (SPR) is regulated and results in a distinctly color change of the system, which can be easily distinguished with the naked eye. Therefore, the concentration of Hx in the fish samples can be semi-quantitatively analyzed with the naked eye. The proposed multicolor Hx sensor has been successfully applied to the detection of Hx in fish samples.

Silica is one of the most abundant materials on the earth, and promises a high potential application in lithium ion battery (LIB). The crucial challenge for SiO2 materials is the huge volume change and poor electrical conductivity during the lithiation and delithiation process which result into the rapid capacity fading and bad cyclability. Herein, we successfully synthesized the multi-shell hollow silica microspheres (MHSM) with hierarchically porous structure via a simple sacrificial template method. The numbers of shell could be simply controlled by the precursor (Na2SiO3) loading. The multi-shell and hierarchically porous structure could endow SiO2 with large volume, good porosity and permeability. These advantages could offer not only the plentiful electrode-electrolyte reaction sites but also a “buffer” to hinder the volume expansion of silica in the Li+ charge-discharge process. The research results showed that LIB assembled with the MHSM exhibited high capacity and long cycle life. The multi-shell and hierarchically porous structures provide a novel morphology of anode materials to enhance rate capability and structural stability of high-capacity electrode materials.

This paper aims to examine the greenhouse gas (GHG) emission profit of the multi-crystalline (multi-Si) photovoltaic installations by conducting life cycle assessments (LCA) for both the traditional coal-fired power plants and the PV-based power plants. The GHG emission rates for both systems are 975.2 g CO 2 -eq./kWh and 36.75 g CO 2 -eq./kWh respectively, and the difference, which represents the unit GHG emission rate profit, is 938.45 g CO2-eq./kWh. The application of a 1MW PV-based power plant was followed, and the annual GHG emission profit for such a system was 2.08 x 10 9 g CO2-eq. Some further discussion was also made, indicating the sources of the data as well as the reasons for the method adoption.

A one-pot and diastereoselective synthesis of quinazoline-2(1H)-thione-containing polycyclic compounds is introduced. The reaction process includes [3 + 2] cycloaddition of azomethine ylides for pyrrolidines, Staudinger-aza-Wittig reaction of azides for iminophosphoranes, formation of isothiocyanates, and finally cyclization of amines to isothiocyanates for dihydroquinazolinethiones.

Sibu yak is famous for its excellent breed in Tibet and has become a magic way for local herdsmen to get rich. The Sibu yak, however, has been identified as an endangered bovine species. In this st...

A topological insulator with magnetic elements shows surprising conductive behavior on its surface, presenting either a hurdle to realizing exotic quantum phenomena or a boon to devices with new charge transport mechanisms.

A fluorescent probe is described for detection of mercury(II) ion by using L-cysteine-modified gold nanoparticles (Cys-AuNP). These were fabricated by a tube-based redox reaction where Cys acts as both the reducing reagent and capping ligand. The Cys-AuNP display red fluorescence, with excitation/emission peaks at 373/625 nm. Owing to the high-affinity of the Hg(II)-Au(I) interaction and the Hg(II)/carboxy or amino group interaction, the presence of Hg(II) cause selective quenching the fluorescence, while other metal ions do not give such an effect. Based on these findings, a method was designed for the determination of Hg(II) that has attractive figures of merit. These include a low limit of detection (1.3 nM), a wide detection range (from 2 nM to 30µM), and excellent specificity. The method was applied to Hg(II) screening in (spiked) tap and river water, and it gave satisfactory results. Graphical abstract Schematic representation of the application of L-cysteine modified gold nanoparticles (Cys-AuNP) for qualitative and quantitative detection of mercury(II) ions. Based on the interaction between Cys-AuNP and mercury(II) ion to quench the red fluorescence of Cys-AuNP, the target mercury(II) can in turn be determined by a fluorometric method.

This study investigated the coupled dynamics of the redox transformation of arsenic-containing ferrihydrite, and arsenate desorption and re-adsorption in presence of sulfide. Batch experiments, various microscopic and spectroscopic analyses collectively revealed that electrons from sulfide competitively transferred to ferrihydrite and no arsenate was reduced. The reductive dissolution of ferrihydrite by sulfide led to the quick formation of FeS that competitively decreased the availability of sulfide for its subsequent reduction of ferrihydrite. The quick formation of FeS was followed by a relatively slow transformation of ferrihydrite to magnetite and other Fe(II)-Fe(III) minerals that were primarily bound to the residual ferrihydrite surfaces. As a result of the preservation of As-containing ferrihydrite and surface covering by the secondary minerals, the majority (> 90%)of sorbed arsenate resided in the solid phase, and

Noble metal nanoparticle-based colorimetric sensors have become powerful tools for the detection of different targets with convenient readout. Among the many types of nanomaterials, noble metal nanoparticles exhibit extraordinary optical responses mainly due to their excellent localized surface plasmon resonance (LSPR) properties. The absorption spectrum of the noble metal nanoparticles was mostly in the visible range. This property enables the visual detection of various analytes with the naked eye. Among numerous color change modes, the way that different concentrations of targets represent vivid color changes has been brought to the forefront because the color distinction capability of normal human eyes is usually better than the intensity change capability. We review the state of the art in noble metal nanoparticle-based multicolor colorimetric strategies adopted for visual quantification by the naked eye. These multicolor strategies based on different means of morphology transformation are classified into two categories, namely, the etching of nanoparticles and the growth of nanoparticles. We highlight recent progress on the different means by which biocatalytic reactions mediated LSPR modulation signal generation and their applications in the construction of multicolor immunoassays. We also discuss the current challenges associated with multicolor colorimetric sensors during actual sample detection and propose the future development of next-generation multicolor qualification strategies.