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The 3D (three-dimensional) oriented nanosheet array FeNi2P electrocatalyst grown on carbon cloth (FeNi2P/CC) is explored in this work. This unique 3D oriented nanosheet array structure can expose more catalytic active sites, promote the penetration of electrolyte solution on the catalyst surface, and facilitate the transfer of ions, thus speeding up the kinetic process of Hydrogen evolution reaction (HER) and Oxygen evolution reaction (OER). At the current densities of 10 mA/cm2 in 1 M KOH solution, the HER overpotential (71 mV) of the FeNi2P/CC self-supporting electrode is very close to that of noble metal HER catalyst of 20% Pt/C (54 mV), and its OER overpotential (210 mV) is 34% lower than that of the precious metal OER catalyst of RuO2 (318 mV), demonstrating the excellent electrocatalytic performance of the FeNi2P/CC catalyst. Moreover, the cell voltage for full water splitting (at 10 mA/cm2 current densities) of the FeNi2P/CC bifunctional electrode cell is 1.52 V, which is 3.8% lower than that of the full noble-metal electrode reference cell (RuO2 || Pt/C, 1.58 V), suggesting that this FeNi2P/CC bifunctional catalyst is likely to replace precious metals to reduce the costs in full water splitting application. According to density functional theory (DFT) calculation results, the introduction of iron atom can change the electronic structure of the Ni2P, so it can reduce the adsorption energy of hydrogen and oxygen, and facilitate the adsorption and desorption of hydrogen and oxygen on the surface of the catalyst, improving its performance of HER and OER.

The Li metal anode is considered one of the most potential anodes due to its highest theoretical specific capacity and the lowest redox potential. However, the scalable preparation of safe Li anodes remains a challenge. In the present study, a LiF-rich protection layer has been developed using self-driven chemical reactions between the Li

The exploration for low-cost bifunctional materials for highly efficient overall water splitting has drawn profound research attention. Here, we present a facile preparation of Mo–P dual-doped Co/o...

TiO2 nanostructures have been one of the most explored metal oxides photocatalysts to apply for environmental remediation. However, its wide band gap results in the underutilization of sunlight for degradation of pollutants. In order to overcome this handicap, the synthesis of TiO2-based composite has brought extraordinary materials. In this study, we design and prepare TiO2/Nb2O5 heterostructures with different molar ratios by using peroxotitanium and peroxoniobium complex as precursors in aqueous solution. The TiO2 exists in the form of anatase while Nb2O5 is amorphous in the composite, leading to a special crystalline TiO2/amorphous Nb2O5 heterostructures. In particular, Nb element is also doped and Ti3+ ions are formed in the TiO2 lattice, leading to a reduced band gap. The unique TiO2/0.25Nb2O5 (Ti:Nb = 2:1) heterostructures can effectively suppress the recombination of photogenerated electrons and holes, and facilitate the charge transfer, resulting in the optimum photocatalytic performance. The nitrogen oxide removal efficiency by TiO2/0.25Nb2O5 is 77.23% in visible light, which is 3.8-folds and 7.0-folds higher than pure TiO2 and Nb2O5. Photocatalytic degradation of acetaminophen by TiO2/0.25Nb2O5 is 90.6% in visible light, which is approximately 2.5-folds higher than pure TiO2 and Nb2O5.

B atoms and cyano groups co-doped graphite carbon nitride with nitrogen vacancies (VN-BC-CN) was explored via one-step in-situ route. A series of comprehensive experiments confirmed that B atoms and cyano groups had been doped into the framework of graphite carbon nitride, forming VN-BC-CN catalyst sample with a large number of nitrogen-vacancy defects. As electron acceptors, B and cyano groups could be used as active sites for nitrogen conversion. The defect level caused by nitrogen vacancy led to red shift of the light absorption edge, which resulted in higher separation efficiency of photo-induced carriers and faster transfer rate of photo-induced electrons for the VN-BC-CN catalyst. This VN-BC-CN catalyst had good photocatalytic nitrogen fixation performance in the ultrapure water without any hole-scavengers. The nitrogen photofixation rate of VN-BC-CN (115.53 μmol g−1 h−1) was 25.5 times that of pure carbon nitride (GCN, 4.53 μmol g−1 h−1). Moreover, NH4+ generation rate hardly decreased after 10 h reaction, and the NH4+ generation rate could reach 79.56 μmol g−1 h−1 in the fifth cycle, showing the good photocatalytic stability of the VN-BC-CN catalyst.

Large-size flexible biomass carbon membranes have been prepared by using inexhaustible chitosan (CS) as carbon source. The microstructure of carbon membranes depends on the pyrolysis temperature, and the resulting membrane has a porous honeycomb-like architecture with N-doping content of 6.3% after the pyrolysis at 1000 °C. The flexible carbon membranes can be directly used as self-standing electrodes for various batteries, that is, with no current collectors, organic binders, or additional conductive agents. The carbon membranes as anodes for potassium-ion batteries exhibit excellent rate performance and a stable reversible capacity of 146 mAh g−1 at 2 A g−1 after 500 cycles, and its sodium-ion storage remains 236 mAh g−1 after 70 cycles. The kinetic analysis of carbon membranes in batteries shows that the surface-controlled mechanism plays a decisive role in the potassium/sodium storage because the honeycomb structure and high proportion of pyridine N-doping can improve the adsorption of K+/Na+ ions and the conductivity. In addition, the main reasons for the capacity degradation of the carbon membrane under long cycle and different current densities are discussed. The CS-derived flexible carbon membranes show a promising application as cost-effective, binder-free electrodes in flexible batteries.

Lithium-sulfur battery is one of the most promising candidates for next-generation energy storage systems, but the serious shuttle effect and sluggish reaction kinetics of polysulfides impair its practical applications. Herein, sulfur-deficient MoS

Transition metal nanostructures are widely regarded as important catalysts to replace the precious metal Pt for hydrogen evolution reaction (HER) in water splitting. However, it is difficult to obtain uniform-sized and ultrafine metal nanograins through general high-temperature reduction and sintering processes. Herein, a novel method of chemical energy-driven lithiation is introduced to synthesize transition metal nanostructures. By taking advantage of the slow crystallization kinetics at room temperature, more surface and boundary defects can be generated and remained, which reduce the atomic coordination number and tune the electronic structure and adsorption free energy of the metals. The obtained Ni nanostructures therein exhibit excellent HER performance. In addition, the bimetal of Co and Ni shows better electrocatalytic kinetics than individual Ni and Co nanostructures, reaching 100 mA cm

Lithium-oxygen batteries (LOBs) have been extensively studied as an attractive secondary battery due to their ultra-high energy density. However, its high charging voltage, poor cycle stability, and low rate performance make its practical applications very limited. Since the positive electrode is the main reaction site of LOBs, improving the structure and catalytic activity of the cathode catalyst is the key method to improve the electrochemical performance. In this work, colored titanium dioxide nanoparticles were synthesized by calcination in argon. Raman and XPS confirmed the existence of more oxygen vacancies and Ti3+ in black TiO2 than gray one. HRTEM analysis also reveals the defective layers of 2–3 nm on the TiO2 surface. Due to the high electrical conductivity and good catalytic activity promoted by oxygen vacancies and Ti3+ ions, the black TiO2-based cathodes have good electrochemical activity and enhanced cycling stability for LOBs. Compared with the gray TiO2 (4.3 V), the black TiO2 nanoparticles show a low overpotential with the charge voltage of 3.7 V. The charging voltage significantly reduced approximately 600 mV, which reduces the battery's side reactions and polarization, and thus enhances the cycling performance of the battery. When the cut-off capacity is 500 mAh g−1, it can run for 108 cycles without significant change in terminal voltage, indicating that black TiO2 is an efficient catalyst for LOBs.

In this work, a kind of three-dimensional (3D) needle branch-like array nanostructured PANI/CoNiP hybrid electrode self-supported on nickle foam (NF) is explored. This 3D needle branch-like array n...

Transition metal oxides have shown an extraordinary potential for lithium-storage capability to date. However, it remains enormous challenge to gain high capacities, good rate performance and cyclability due to their inferior conductivity. To address this issue, oxygen vacancies (VOs) implanted ultrathin WO3 nanorods (the diameter around 5 nm and the length less than 100 nm) composed with reduced graphene oxide (namely WO3-x/rGO), were synthesized by proposing a logical design. For the sake of better showing the outcome of such configuration, holy nanosheets of pure WO3 anode were proposed to compare with nanorods WO3-x/rGO one in terms of electrochemical properties, and they were obtained via annealing H2WO4/rGO precursor in air and argon atmosphere with the same annealing ramp, respectively. By contrast, both electron paramagnetic resonance and X-ray photoelectron spectroscopic characterizations demonstrate the existence of VOs in WO3-x/rGO composite. The generation of VOs together with the reserve of rGO, the conductivity of WO3-x/rGO anode is distinctly enhanced, which is then verified by the compared electrochemical performance in this work. It is clearly shown that the WO3-x/rGO nanocomposite displays a capacity of 745 mAh g−1 at a current density of 0.1 A g−1 after 200 cycles and excellent cycling stability up to 1000 cycles with capacity of 428 mAh g−1 at 1 A g−1. These findings exhibit that nanorods WO3-x/rGO nanocomposite is a promising candidate for high-performance Li-ion battery anode.

The introduction of a dual-functional interlayer into lithium-sulfur batteries (LSBs) provides many opportunities for restraining the "shuttle effect" and enhancing sluggish sulfur conversion kinetics. Tuning the band structure of the metal sulfide provides an opportunity to enhance its catalytic activity, which plays an important role in suppressing the "shuttle effect" of lithium polysulfides (LiPSs) in LSBs. Here were present a Co9S8@MoS2 core-shell heterostructure anchored to a carbon nanofiber (Co9S8@MoS2/CNF), developed as an interlayer for suppressing the shuttle effect of LiPSs. The fabricated composite heterostructure is determined to be an effective alternative material that combines the synergistic relationship between chemisorption and electrochemical catalysis. We find that the band structure of the MoS2 shell can be effectively tuned by the Co9S8 core and that the Co9S8@MoS2/CNF can capture the LiPSs, providing excellent catalytic ability to convert LiPSs into Li2S2, with subsequent transformation from Li2S2 to Li2S. Importantly, high capacities of 1002 and 986 mAh g-1 can be retained after 50 cycles with high-sulfur loadings of 6 and 10 mg cm-2. Our results highlight the design of an atomic-scale heterostructure as a multifunctional interlayer providing a synergistic relationship between adsorption and catalysis. The net result is an effective retardation of the shuttling of LiPSs and an enhancement of the electrochemical redox reactions of LiPSs. This work shows great promise toward the development of practical applications of LSBs.

Application of the graphene-based composites in practice was hampered due to the lack of the controllable synthesis strategy. To solve the problem, we envisaged the organic nanodroplets as a nano-reaction environment to obtain the organic nanoframes by photo-polymerization, then to directly graphitize for the graphene-based materials. In such strategy, two-dimensional laminar matrix of graphene nanosheets (2DLMG) was obtained with millimeter-scale surface, which rendered the matrix high electron conductivity. Thanks to the confinement effect of the nanodroplets, the composited materials were homogeneously dispersed in the organic nanoframes. Then, the organic nanoframes converted directly to 2DLMG-based composites after calcination. In this paper, the transformation from organic nanoframes to 2DLMG has been revealed in detail by comprehensive analyses from SEM, XRD and XPS. To demonstrate the versatility of 2DLMG, the superiority in lithium ion battery has been indicated by the high specific capacity (565 mA h g−1), high cycling performance after 500 cycles and the 100% retention capacity in rate measurement. For the synthesis of the composites, Sn nanoparticles and γ-Fe2O3 nanoparticles were distributed in 2DLMG without the aggregation with high loading. The proposed organic molecule confinement reaction strategy was expected to point out a promising direction for the preparation of graphene-based materials.

The exploration for low-cost bifunctional materials for highly efficient overall water splitting has drawn profound research attention. Here, we present a facile preparation of Mo-P dual-doped Co/oxygen-deficient Co

We present a precipitation-strengthening strategy to produce a strong and ductile alloy at a broad range of temperatures., High-entropy alloys (HEAs), as an emerging class of materials, have pointed a pathway in developing alloys with interesting property combinations. Although they are not exempted from the strength-ductility trade-off, they present a standing chance in overcoming this challenge. Here, we report results for a precipitation-strengthening strategy, by tuning composition to design a CoNiV-based face-centered cubic/B2 duplex HEA. This alloy sustains ultrahigh gigapascal-level tensile yield strengths and excellent ductility from cryogenic to elevated temperatures. The highest specific yield strength (~150.2 MPa·cm3/g) among reported ductile HEAs is obtained. The ability of the alloy presented here to sustain this excellent strength-ductility synergy over a wide temperature range is aided by multiple deformation mechanisms i.e., twins, stacking faults, dynamic strain aging, and dynamic recrystallization. Our results open the avenue for designing precipitation-strengthened lightweight HEAs with advanced strength-ductility combinations over a wide service temperature range.

The 3D (three-dimensional) oriented nanosheet array FeNi

Using polymer electrolytes with relatively high mechanical strength, enhanced safety, and excellent flexibility to replace the conventional liquid electrolytes is an effective strategy to curb the Li-dendrite growth in Li-metal batteries (LMBs). However, low ionic conductivity, unsatisfactory thermal stability, and narrow electrochemical window still hinder their applications. Here, we fabricate Li0.35La0.55TiO3 (LLTO) nanofiber-enabled poly(vinylidene fluoride) (PVDF)-based composite polymer electrolytes (CPEs) with enhanced mechanical property and wide electrochemical window. The results show that 15 wt % of LLTO nanofibers synergize with PVDF, giving a flexible electrolyte membrane with significantly improved performance, such as high ionic conductivity (5.3 × 10-4 S cm-1), wide electrochemical window (5.1 V), high mechanical strength (stress 9.5 MPa, strain 341%), and good thermal stability (thermal degradation 410 °C). In addition, an all-solid-state Li-metal battery of sandwich-type LiFePO4/PVDF-CPE (15 wt % of LLTO)/Li delivers satisfactory cycling stability and outstanding rate performance. A reversible capacity of 121 mA h g-1 is delivered at 1 C after 100 cycles. This work exemplifies that the introduction of LLTO nanofibers can improve the electrochemical performances of PVDF-based CPEs used as electrolytes for all-solid-state LMBs.

A novel nitrogen and oxygen dual-doped porous carbon (NOPC) has been prepared from the aerial roots of ficus microcarpas through a facile carbonization and activation approach using KOH as the chemical activating agent. The obtained NOPC has very large specific surface area of 2294 m2 g−1 and high pore volume of 1.15 cm3 g−1. Thanks to the high specific surface area and the doping of nitrogen and oxygen, the prepared NOPC/S cathode with a sulfur content of 55.9% shows a high initial discharge capacity of 1338 mA h g−1 at 0.1 C and retains 1047 mA h g-1 after 200 cycles. What is more, the NOPC/S-62.9% cathode also remains high capacity of 1036 mA h g-1 and the coulomb efficiency remains 98.3% after 200 cycles. Taking into account of the low cost, green and sustainable development, NOPC/S composites show good prospects in the application of lithium-sulfur batteries.

Layered two-dimensional MoSe2 has raised much interest in lithium/sodium ion batteries (LIBs/SIBs) due to its unique structure and high theoretical capacity. In this work, we have fabricated MoSe2@carbon cloth (MoSe2@CC) composites through an in situ hydrothermal approach followed by an annealing treatment. The as-synthesized MoSe2@CC composites are constructed by MoSe2 nanoflowers anchored on CC network, which can be directly used as binder-free anodes for LIBs and SIBs. As an anode for LIBs, the MoSe2@CC performs excellent rate capacity (1337, 1092, 952, 831 and 749 mAh g−1 at current densities of 0.1, 0.2, 0.5, 1.0, and 2.0 A g−1) and super long-life cycling stability (638 mAh g−1 remains after 1200 cycles at 5 A g−1). As for SIBs, the MoSe2@CC electrode delivers a high initial discharge capacity of 839 mAh g−1 and excellent long-life cycling stability, retaining 202 mAh g−1 after 1000 cycles. Kinetics results indicate that the Li+ and Na+ storages in MoSe2@CC are both dominated by surface-based pseudocapacitive process, which greatly improves the rate performance of LIBs/SIBs. The CC provides a conductive network and an excellent utilization rate of the active material MoSe2 to improve the electrochemical performance.

Lithium-sulfur (Li-S) battery is an appealing technology due to its conspicuous advantages in the area of energy storage. However, many challenges remain, such as the design of cathode with high sulfur loading, suppression of shuttle effects, enhanced performance and large scale preparation. Here, we report a novel 3D free-standing nitrogen-doped porous carbon foam (PCF) obtained by carbonization of the natural melaleuca bark, and apply it as a binder-free current collector to host sulfur for Li-S cells. This study shows that the obtained N-doped PCF possesses sheet-like porous carbon structures, high specific surface area, and large pore volume. Taking advantage of these properties, the resulting PCF/S electrodes exhibit an initial discharge capacity of 1330 mAh g−1, good reversible capacity of 880 mAh g−1 after 100 cycles at 0.2 C and deliver an excellent cycling stability (over 250 cycles at 0.5 C with 0.14% capacity fading per cycle). In addition, the PCF/S electrodes with large areal mass loading of 6 mg cm−2 show a high areal capacity of 4.14 mAh cm−2, revealing a great potential for high energy Li-S batteries.

Sn-based anode for lithium-ion batteries (LIBs) has been received extensive concern, due to its high theoretical specific capacity. However, its poor stability induced by serious volume changes during charge/discharge process limits its application. MoS 2 possesses a 2-dimisional (2D) graphene-like layered structure facilitates lithium ions insertion and extraction and can be served as the buffer to alleviate the volume variation. Unfortunately, 2D MoS2 nanosheets are highly susceptible to stacking/restacking during cycles, which is fatal to their capacity retention. Herein, a novel MoS2@SnO2-SnS2 composite has been designed and fabricated via a two-step simple hydrothermal route. Due to the synergistic effect between the ultrathin MoS2 nanosheets and the SnO2-SnS2 nanosheets, the MoS2@SnO2-SnS2 composite exhibits excellent electrochemical performance as anode for LIBs.

Ruthenium (Ru) single atoms were decorated on the surface of the graphitic carbon nitride (g-C3N4) successfully in this work. By varieties of characterization, the existence of Ru single atoms and the defects (cyano groups) caused in the process of synthesis have been confirmed. The catalyst decorated by Ru atoms (Ru-CCN-0.05) had better absorption capacity and a wider absorption range of light than the catalyst with no Ru atoms loading on (Ru-CCN-0). Without the help of hole-scavengers, the rate of photocatalytic nitrogen fixation of Ru-CCN-0.05 in ultra-pure water was 2.26 mg L−1 gcat −1 h−1, 1.5 times that of bare g-C3N4.

TiO

B atoms and cyano groups co-doped graphite carbon nitride with nitrogen vacancies (VN-BC-CN) was explored via one-step in-situ route. A series of comprehensive experiments confirmed that B atoms and cyano groups had been doped into the framework of graphite carbon nitride, forming VN-BC-CN catalyst sample with a large number of nitrogen-vacancy defects. As electron acceptors, B and cyano groups could be used as active sites for nitrogen conversion. The defect level caused by nitrogen vacancy led to red shift of the light absorption edge, which resulted in higher separation efficiency of photo-induced carriers and faster transfer rate of photo-induced electrons for the VN-BC-CN catalyst. This VN-BC-CN catalyst had good photocatalytic nitrogen fixation performance in the ultrapure water without any hole-scavengers. The nitrogen photofixation rate of VN-BC-CN (115.53 μmol g

The genetic improvement of nitrogen use efficiency (NUE) of crops is vital for grain productivity and sustainable agriculture. However, the regulatory mechanism of NUE remains largely elusive. Here, we report that the rice Grain number, plant height, and heading date7 (Ghd7) gene genetically acts upstream of ABC1 REPRESSOR1 (ARE1), a negative regulator of NUE, to positively regulate nitrogen utilization. As a transcriptional repressor, Ghd7 directly binds to two Evening Element-like motifs in the promoter and intron 1 of ARE1, likely in a cooperative manner, to repress its expression. Ghd7 and ARE1 display diurnal expression patterns in an inverse oscillation manner, mirroring a regulatory scheme based on these two loci. Analysis of a panel of 2656 rice varieties suggests that the elite alleles of Ghd7 and ARE1 have undergone diversifying selection during breeding. Moreover, the allelic distribution of Ghd7 and ARE1 is associated with the soil nitrogen deposition rate in East Asia and South Asia. Remarkably, the combination of the Ghd7 and ARE1 elite alleles substantially improves NUE and yield performance under nitrogen-limiting conditions. Collectively, these results define a Ghd7-ARE1-based regulatory mechanism of nitrogen utilization, providing useful targets for genetic improvement of rice NUE.

Developing zero-strain electrode materials with high capacity is crucial for lithium-ion batteries (LIBs). Here, a new zero-strain composite material made of ultrasmall Si nanodots (NDs) within metal organic framework-derived nanoreactors (Si NDs⊂MDN) through a novel space-confined catalytic strategy is reported. The unique Si NDs⊂MDN anode features a low strain (3%) and a high theoretical lithium storage capacity (1524 mAh g

The introduction of a dual-functional interlayer into lithium-sulfur batteries (LSBs) provides many opportunities for restraining the "shuttle effect" and enhancing sluggish sulfur conversion kinetics. Tuning the band structure of the metal sulfide provides an opportunity to enhance its catalytic activity, which plays an important role in suppressing the "shuttle effect" of lithium polysulfides (LiPSs) in LSBs. Here were present a Co

Sn@Graphene composites as anode materials in Lithium-ion batteries have attracted intensive interest due to the inherent high capacity. On the other side, the high atomic ratio (Li4.4Sn) induces the pulverization of the electrode with cycling. Thus, suppressing pulverization by designing the structure of the materials is an essential key for improving cyclability. Applying the nanotechnologies such as electrospinning, soft/hard nano template strategy, surface modification, multi-step chemical vapor deposition (CVD), and so on has demonstrated the huge advantage on this aspect. These strategies are generally used for homogeneous dispersing Sn nanomaterials in graphene matrix or constructing the voids in the inner of the materials to obtain the mechanical buffer effect. Unfortunately, these processes induce huge energy consumption and complicated operation. To solve the issue, new nanotechnology for the composites by the bottom-up strategy (Organic Molecule Confinement Reaction (OMCR)) was shown in this report. A 3D organic nanoframes was synthesized as a graphene precursor by low energy nano emulsification and photopolymerization. SnO2 nanoparticles@3D organic nanoframes as the composites precursor were in-situ formed in the hydrothermal reaction. After the redox process by the calcination, the Sn nanoparticles with nanovoids (~100 nm, uniform size) were homogeneously dispersed in a Two-Dimensional Laminar Matrix of graphene nanosheets (2DLMG) by the in-situ patterning and confinement effect from the 3D organic nanoframes. The pulverization and crack of the composites were effectively suppressed, which was proved by the electrochemical testing. The Sn nanoparticles@2DLMG not delivered just the high cyclability during 200 cycles, but also firstly achieved a high specific capacity (539 mAh g−1) at the low loading Sn (19.58 wt%).

Bramble-like NaVMoO6/C nanofibers with remarkable lithium-storage property are fabricated via a simple electrospinning method. The NaVMoO6 nanoparticles with average size of 84 nm are uniformly embedded into the carbon nanofibers at loading of 77.2 wt%. The unique architecture of the resulting nanocomposite has great advantages like enhanced surface-to-volume ratio, reduced ion transport lengths and strengthened electron transfer along the longitudinal direction. As a new-type anode for lithium-ion batteries (LIBs), NaVMoO6/C composite demonstrates a stable capacity of 1013 and 682 mAh g−1 at the current density of 0.1 and 1 A g−1, respectively. Furthermore, the structure evolution mechanism during the first discharge process is carefully researched by ex-situ X-ray diffraction and X-ray photoelectron spectroscopy. It is found that the NaVMoO6 crystals begin to change after being embedded with a few equivalent Li+ when discharging to 2.2 V. With the continuous intercalation of Li+ ions, the main crystal form of the electrode is V2O5 at the potential of about 2.0 V. At low potential (≈ 1.2 V vs. Li/Li+), the formed V2O5 is transformed into LiVO2. In addition, the volume expansion of the NaVMoO6 particles is alleviated due to the confining effect of carbon nanofibers. Consequently, NaVMoO6/C nanofibers demonstrate a high reversible capacity even at high rate.