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A new homojunction is developed by in situ decorating g-C3N4 (CN) nanosheets with a C–N compound broken by s-triazine units (BST). The BST fragments rapidly transfer photogenerated electrons from the CN conduction band to generate hydrogen.

By virtue of complexing Ni/Co/Mn ions with glucose under solvothermal conditions, well-defined spherical Ni/Co/Mn-gluconate with tunable size and elemental composition is prepared and readily converted into yolk–shelled Li(NixCoyMn1−x−y)O2.

TiNb2O7 (TNO) as a promising candidate anode for lithium-ion batteries (LIBs) shows obvious advantages in terms of specific capacity and safety, but which undergoes the intrinsic poor electrical and ionic conductivity. Herein, we propose a simple synthesis strategy of mesoporous TNO via a polymeric surfactant-mediated evaporation-induced sol-gel method, using polyvinylpyrrolidone (PVP) with different molecular weights (average Mw: 10000/58000/1300000) as the regulating agent, which greatly affects the lithium storage performance of the as-prepared TNO. The optimized TNO (i.e., PVP of 58000) delivers a high reversible capacity of 303.1 mAh/g at 1 C, with a retention rate of 73.4% (222.5 mAh/g) after 300 cycles. Even at 5 C, a high reversible capacity of 185.6 mAh/g can be achieved, with a retention rate of 72.3% after 1000 cycles. The superior lithium storage behavior is attributed to the fine mesoporous framework consisting of interconnected TNO nanocrystallites with high specific surface area and high mesoporosity, which greatly increases the active sites, improves the Li+ diffusion kinetics and alleviates volume fluctuation induced by the repetitive Li+ insertion-extraction processes.

Metal oxides are prospective alternative anode materials to the commercial graphite for lithium ion batteries (LIBs), while their practical application is seriously hampered by their poor conductivities and large volume changes. Herein, we report the controllable synthesis of amorphous/crystalline MnCo2Ox nanoparticles within porous carbon nanofibers (marked as MCO@CNFs) through a facile electrospinning strategy and subsequent annealing reactions. The phase structures from Co/MnOX to amorphous MnCo2Ox and crystalline MnCo2O4.5 can be readily tuned by thermal reduction/oxidation under controlled atmosphere and temperature. When examined as anode for LIBs, the optimized MCO@CNFs delivers a high stable capacity of 780.3 mA h g−1 at 200 mA g−1 after 250 cycles, which is attributed to the synergistic effect of the distinctive amorphous structure and defective carbon nanofiber matrices. Specifically, the amorphous structure with rich defects offers more reactive sites and multiple pathways for the Li+ diffusion, while carbon hybridization sufficiently improves the electrode conductivities as well as buffers the volume changes. More importantly, we demonstrate a convenient synthesis strategy to control the metal-to-oxide structure evolution within carbon matrices, which is of great importance in exploring high-performance electrodes for next generation LIBs.

Few-layered graphene-like MoS2/carbon composite with porous hierarchical nanostructures was prepared via a template-assisted pyrolysis method, which demonstrated excellent sodium storage performance with high pseudocapacitance contribution.

Titanium dioxide (TiO2) as a potential anode material for sodium-ion batteries (SIBs) suffers from the intrinsic poor electronic conductivity and sluggish ionic diffusivity, thus usually leading to the inferior electrochemical performance. Herein, we demonstrate a facile strategy to enhance the sodium storage performance of TiO2 via vanadium (V) doping, using the pre-synthesized V-doped Ti-based metal–organic framework (MOF, MIL-125) as the precursor, which can be converted into the V-doped TiO2 with simultaneous carbon hybridization and controlled V-doping amount (denote as VxTiO2@C, where × represents the V/Ti molar ratio (RV/Ti)). V-doping not only affects the morphology of the MIL-125 changing from thick to thin nanotablets, but also greatly enhances the electrochemical performance of the VxTiO2@C. When used as an anode for SIBs, the V0.1TiO2@C exhibits a much higher reversible capacity of 211 mAh/g than that for the undoped TiO2@C (only 156 mAh/g) after 150 cycles at 100 mA/g. Even after high-rate long-term cycling, the V0.1TiO2@C can still display a capacity of 180 mAh/g with a high capacity retention of 137% at 1000 mA/g after 4500 cycles. Structural/electrochemical measurements reveal that V-doping induces the formation of oxygen vacancies as well as Ti3+ species, which efficiently improve the electric conductivity and the ion diffusivity of the electrode. Meanwhile, the thinner V0.1TiO2@C nanotablets with porous structure and carbon hybridization could facilitate the ion/electron transfer with shortened diffusion pathways.

Dissolution of intermediate sodium polysulfides (Na2Sx; 4≤x≤8) is a crucial obstacle for the development of room-temperature sodium-sulfur (Na-S) batteries. One promising strategy to avoid this issue is to load short-chain sulfur (S2-4), which could prohibit the generation of soluble polysulfides during the sodiation process. Herein, unlike in the previous reported cases where short-chain sulfur was stored by confinement within a small-pore-size (≤0.5 nm) carbon host, we report a new strategy to generate short-chain sulfur in larger pores (>0.5 nm) by the synergistic catalytic effect of CoS2 and appropriate pore size. Based on density functional theory calculations, we predict that CoS2 can serve as a catalyst to weaken the S-S bond in the S8 ring structure, facilitating the formation of short-chain sulfur molecules. By experimentally tuning the pore size of the CoS2-based hosts and comparing their performances as cathodes in Na-S and Li-S batteries, we conclude that such a catalytic effect depends on the proximity of sulfur to CoS2. This avoids the generation of soluble polysulfides and results in superior electrochemical properties of the composite materials introduced here for Na-S batteries. As a result, the optimized CoS2/N-doped carbon/S electrode showed excellent electrochemical performance with high reversible specific capacities of 488 mA h g-1 (962 mA h g(s)-1) after 100 cycles (0.1 A g-1) and 403 mA h g-1 after 1000 cycles (1 A g-1) with a superior rate performance (262 mA h g-1 at 5.0 A g-1).

Transition metal oxides/selenides as anodes for sodium-ion batteries (SIBs) suffer from the insufficient conductivity and large volumetric expansion, which leads to the poor electrochemical performance. To address these issues, we herein demonstrate a facile selenization method to enhance the sodium storage capability of CoMoO4 nanoparticles which are encapsulated into the electrospun carbon nanofibers (CMO@carbon for short). The partially and fully selenized CoMoO4 within carbon nanofibers (denote as CMOS@carbon and CMS@carbon, respectively) can be readily obtained by controlling the annealing temperature (at 400 and 600 °C, correspondingly). When examined as anode materials for SIBs, the CMOS@carbon nanofibers display an outstanding electrochemical performance with a higher reversible capacity of 396 mA h g−1 after 200 cycles at 0.2 A g−1 and a high-rate capacity of 365 mA h g−1 at 2 A g−1, as compared with the CMO@carbon and CMS@carbon counterparts. The enhanced sodium storage performance of the CMOS@carbon can be owing to the partial selenization of the CoMoO4 nanoparticles which are rooted into the porous electrospun carbon nanofibers, thus endowing them with superior ionic/electronic charge transfer efficiencies and a cushion against the electrode pulverization during cycling. Moreover, this work proposed a useful strategy to enhance the sodium storage performance of metal oxides via controlled selenization, which is promising for exploiting the advanced anode materials for SIBs.

Iron-based anodes for lithium-ion batteries (LIBs) with higher theoretical capacity, natural abundance and cheapness have received considerable attention, but they still suffer from the fast capacity fading. To address this issue, we report a facile synthesis of plate-like carbon-supported Fe3C nanoparticles through chemical blowing/carbonization under calcination. The ultrafine Fe3C nanoparticles are prone to be oxidized when exposing in air; thus, Fe3C/C with mild oxidization and the fully oxidized product of Fe2O3/C are successfully prepared by controlling the oxidization condition. When applied as an anode material in LIB, the Fe3C/C electrode demonstrates excellent cycle stability (826 mAh·g−1 after 120 cycles under 500 mA·g−1) and rate performance (410.6 mAh·g−1 under 2 A·g−1), compared with the Fe2O3/C counterpart. The enhanced electrochemical performance can be ascribed to the synergetic effect of the Fe3C with mild oxidation and the unique hierarchical structure of plate-like carbon decorated with Fe3C catalyst. More importantly, this work may offer new approaches to synthesize other transition metal (e.g., Co, Ni)-based anode material by replacing the precursor ingredient.

We report a facile solvothermal synthesis of hollow TiO2 nanospheres using phenolic resin nanospheres as templates under magnetic stirring conditions, followed by annealing. The as-prepared hollow TiO2 nanospheres show an inner diameter of ∼400 nm, a shell thickness of ∼45 nm, and a high specific surface area of 33.8 m2 g−1. When used as anode materials for lithium-ion batteries and sodium-ion batteries, the hollow TiO2 demonstrates excellent cycling stability and rate capability, delivering high lithium storage capacities of 178/138 mA h g−1 at 0.2/1.0 A g−1 after 200/1000 cycles, and high sodium storage capacities of 213/177/115 mA h g−1 after 200/1000/4000 cycles at 0.2/1.0/5.0 A g−1. The outstanding electrochemical performance is related to the robust structural stability of the hollow nanostructured TiO2, which can be expected as a promising anode material for next generation alkali metal ion batteries.

Transition-metal oxides/sulfides have been widely applied for energy storage because of their high-theoretical capacity and natural abundance with low prices, but they suffer from the volume change...

Transition metal oxides with spinel AB2O4 phases are deemed as potential anode materials for lithium-ion batteries (LIBs), attributing to high specific capacities, low cost, and environmental frien...

SnO2 suffers from the severe pulverization problem when used as an anode material for lithium ion batteries (LIBs). To overcome its drawbacks, hybridizing nanosized SnO2 with carbon-based materials is very impactful, and we herein successfully synthesize ultrasmall SnO2 nanodots (average size of around 5 nm) within the channels of the commercial ordered mesoporous carbon (CMK-3), in which the tin precursor is prefilled under a vacuum and then is easily converted into SnO2 by annealing at 350 °C in air. The as-prepared SnO2@CMK-3 composite demonstrates good lithium storage properties, displaying a discharge capacity of 898.8 mA h/g at the 150th cycle at 500 mA/g, apparently higher than that for the bare SnO2 and CMK-3 electrodes. The superior electrochemical performance of SnO2@CMK-3 can be due to the high conductivity and vast pore volume of the CMK-3 carbon matrices, which efficiently alleviate the volume change induced pulverization and enhance the electrode conductivity. Besides, the uniform distribution of the ultrasmall SnO2 nanodots within CMK-3 maximally enlarges the lithium storage sites and minimizes the effect of the volume variation.

We report the fabrication of well-defined phase-pure Mn

Alloy-/conversion-type metal oxides usually exhibit high theoretical lithium storage capacities but suffer from the large volume change induced electrode pulverization and the poor electric conductivity, which limit their practical applications. Hybrid/mixed metal oxides with different working mechanisms/potentials can display advantageous synergistic enhancement effect if delicate structure engineering is performed. Herein, atomically hybridized SnO2/Co3O4 nanocomposites with amorphous nature are successfully cast onto the porous N-doped carbon (denoted as NC) nanoflakes through facile pyrolysis of the tin (II) 2-ethylhexanoate (C16H30O4Sn) and cobalt (II) 2-ethylhexanoate (C16H30O4Co) mixture within NC nanoflakes in air at 300 °C for 1 h. The Sn/Co atomic ratio and the loading amount of SnO2/Co3O4 can be readily controlled, whose effect on lithium storage are investigated as anodes for lithium ion batteries (LIBs). Notably, SnO2/Co3O4@NC (RSn/Co = 1.25) nanoflakes exhibit the most excellent lithium storage properties, delivering a reversible capacity of 1450.3 mA h g−1 after 300 cycles at 200 mA g−1, which is much higher than that of the single metal oxide SnO2@NC and Co3O4@NC electrodes.

CoMoO4 nanoparticles have been successfully in-situ formed and simultaneously embedded within the porous carbon nanofibers (CoMoO4/CNFs) via a facile electrospinning-annealing strategy. The porous CoMoO4/CNFs exhibit a specific surface area of 255.3 m2/g and a pore volume of 0.52 cc/g with average pore diameter of 43.5 nm. The carbon content in the CoMoO4/CNFs can be readily controlled by adjusting the annealing temperature. When examined as anode materials for lithium ion batteries (LIBs), the CoMoO4/CNFs demonstrate superior electrochemical performance, delivering a high reversible capacity of 802 mA h/g after 200 cycles at 200 mA/g and a high-rate capacity of 574 mA h/g at 2000 mA/g. The excellent lithium storage behavior can be attributed to the incorporation of CoMoO4 nanoparticles into the porous N-doped graphitic carbon nanofibers, which efficiently buffer the volume changes of CoMoO4 upon lithiation/delithiation and maintain the overall electrode conductivity/integrity.

Lithium–sulfur (Li–S) batteries as among the most promising energy storage devices possess high theoretical capacity and energy density but suffer from the polysulfide dissolution, which hinders th...

We report the facile synthesis of molybdenum disulfide (MoS2) nanosheets on graphene nanosheets (MoS2@GNSs) via simple thermal decomposition of ammonium tetrathiomolybdate in Ar-H2 atmosphere. When used as anode materials for sodium-ion batteries (SIBs), the as-prepared MoS2@GNSs electrode delivers reversible capacities of 389 and 383 mA h g−1 at current densities of 200 mA g−1 and 500 mA g−1 after 200 cycles, respectively, which is much higher than that of the MoS2 electrode (253 mA h g−1 after 171 cycles at 200 mA g−1). The superior sodium storage performance of MoS2@GNSs including excellent cycle stability and rate performance can be attributed to the introduction of graphene materials, which not only buffer the volume changes of MoS2 upon sodiation/desodiation but also improve the electrical conductivity.

We report an amorphorization-hybridization strategy to enhance lithium storage by casting atomically mixed amorphorized SnO2/MoO3 into porous foam-like carbon nanoflakes (denote as SnO2/MoO3@CNFs, or SMC in short), which are simply prepared by annealing tin(II)/molybdenum(IV) 2-ethylhexanoate within CNFs under ambient atmosphere at a low temperature (300 °C). The SnO2/MoO3 loading amount within CNFs can be easily adjusted by controlling the Sn/Mo/C precursors. When examined as lithium ion battery (LIB) anode materials, the amorphorized SnO2/MoO3@CNFs with carbon content of 32 wt% (also denote as SMC-32, in which the number represents the carbon content) deliver a high reversible capacity of 1120.5 mA h/g after 200 cycles at 200 mA/g and then 651.5 mA h/g after another 300 cycles at 2000 mA/g, which is much better than that of the crystalline SnO2/CNFs (carbon content of 34 wt%), MoO3/CNFs (carbon content of 22.7 wt%), or SnO2/MoO3@CNFs (with lower carbon contents of 11 and 25 wt%). The electrochemical measurements as well as the ex situ structure characterization clearly suggest that combination of amorphorization and hybridization of SnO2/MoO3 with CNFs synergistically contributes to the superior lithium storage performance with high pseudocapacitive contribution.

Metal oxides are prospective alternative anode materials to the commercial graphite for lithium ion batteries (LIBs), while their practical application is seriously hampered by their poor conductivities and large volume changes. Herein, we report the controllable synthesis of amorphous/crystalline MnCo

Titanium dioxide (TiO

Dissolution of intermediate sodium polysulfides (Na

High-yield rice cultivation is an effective way to address the increasing food demand worldwide. Correct classification of high-yield rice is a key step of breeding. However, manual measurements within breeding programs are time consuming and have high cost and low throughput, which limit the application in large-scale field phenotyping. In this study, we developed an accurate large-scale approach and presented the potential usage of hyperspectral data for rice yield measurement using the XGBoost algorithm to speed up the rice breeding process for many breeders. In total, 13 japonica rice lines in regional trials in northern China were divided into different categories according to the manual measurement of yield. Using an Unmanned Aerial Vehicle (UAV) platform equipped with a hyperspectral camera to capture images over multiple time series, a rice yield classification model based on the XGBoost algorithm was proposed. Four comparison experiments were carried out through the intraline test and the interline test considering lodging characteristics at the midmature stage or not. The result revealed that the degree of lodging in the midmature stage was an important feature affecting the classification accuracy of rice. Thus, we developed a low-cost, high-throughput phenotyping and nondestructive method by combining UAV-based hyperspectral measurements and machine learning for estimation of rice yield to improve rice breeding efficiency.

We investigate how sell-side analysts adjust their earnings forecasts following ESG incidents. We find that following negative ESG news, analysts significantly downgrade their earnings forecasts at all horizons, including long-term. Forecast revisions account for all the negative impact of ESG incidents on firm values, implying no change in the discount rate. The negative revision of earnings forecasts reflects lower expectations on future sales (rather than higher future costs). In Europe, analysts who exhibit a stronger sensitivity to ESG news provide significantly more precise forecasts than their peers.

We study product differentiation in the mutual fund industry. We design a model in which funds with heterogeneous perceived quality can choose their level of product differentiation. In equilibrium, high quality funds choose broad market designs (i.e., low differentiation) appealing to many investors, while low quality funds adopt niche designs (i.e., high differentiation) that investors either love or loath. Using as a measure of fund differentiation the degree of textual uniqueness of investment strategy description in fund prospectuses, we confirm empirically that funds with lower expected performance tend to differentiate more. We use the issuance of Morningstar rating to previously unrated funds as an exogenous shock to perceived quality to identify the economic mechanism. We find that funds receiving a low rating increase their product differentiation. The effect is mainly concentrated on funds run by small management companies, a feature associated with lower performance. This increase in product differentiation makes funds more likely to survive. It also has a market-level impact on the menu of funds available to investors.

Transition metal oxides/selenides as anodes for sodium-ion batteries (SIBs) suffer from the insufficient conductivity and large volumetric expansion, which leads to the poor electrochemical performance. To address these issues, we herein demonstrate a facile selenization method to enhance the sodium storage capability of CoMoO

Sodium-ion batteries (SIBs) have been recognized as the promising alternatives to lithium-ion batteries for large-scale applications owing to their abundant sodium resource. Currently, one significant challenge for SIBs is to explore feasible anodes with high specific capacity and reversible pulverization-free Na

We design and fabricate a novel hybrid with amorphous lithium vanadate (LiV3Ox, LVO for short) uniformly encapsulated into carbon nanofibers (denoted as LVO@CNFs) via an easy electrospinning strategy followed by proper postannealing. When examined for use as anode materials for lithium-ion batteries (LIBs), the optimized LVO@CNFs present a high discharge capacity of 603 mAh g-1 with a capacity retention as high as 90% after 200 cycles at 0.5 A g-1 and a high rate capacity of 326 mAh g-1 after 400 cycles even at a high rate of 5 A g-1. The superior electrochemical performance with excellent cycling stability and rate capability is attributed to the full encapsulation of the amorphous LVO into the conductive carbon nanofibers, which hold enlarged electrochemically active sites for lithium storage, facilitate the charge transfer, and efficiently alleviate the volume changes upon lithium insertion/extraction. More importantly, the current synthesis can be a general strategy to fabricate various alkaline earth metal vanadates, which is promising for developing advanced electrochemical energy storage devices.

Na-Se batteries have their drawbacks such as large volumetric expansion and shuttle effect related to generation of soluble sodium polyselenides. To address these issues, a nitrogen and oxygen codoped flower-like porous carbon host is derived from a Ni-based metal–organic framework (MOF) for Se storage. The use of 4,4′-oxybisbenzoic acid and 4,4′-dimethyl-2,2′-bipyridyl ligands ensure the in-situ doping of the carbon host with oxygen and nitrogen upon carbonization of MOF, which increases its polarity and restricts the diffusion of selenium. Highly porous microflower-like carbon morphology provides sufficient space for Se storage. To avoid undesirable aggregation of Se particles which happens when using conventional melt-diffusion method, we employed a vapor-infiltration method for Se loading, which ensures the homogeneous dispersion of selenium and high utilization of pores in the carbon host. Density functional theory calculations confirmed that the increased polarity of the carbon host due to N,O codoping promotes the adsorption of polyselenides. When tested as a cathode for sodium-selenium battery, the optimized carbon/selenium composite shows an excellent electrochemical performance.