Lithium–sulfur (Li–S) batteries have attracted considerable attention over the last two decades because of a high energy density and low cost. However, the wide application of Li–S batteries has been ...severely impeded due to the poor electrical conductivity of S, shuttling effect of soluble lithium polysulfides (LiPSs), and sluggish redox kinetics of S species, especially under high S loading. To address all these issues, a Ni–CeO2 heterostructure‐doped carbon nanofiber (Ni‐CeO2‐CNF) is developed as an S host that combines the strong adsorption with the high catalytic activity and the good electrical conductivity, where the LiPSs anchored on the heterostructure surface can directly gain electrons from the current collector and realize a fast conversion between S8 and Li2S. Therefore, Li–S batteries with S@Ni‐CeO2‐CNF cathodes exhibit superior long‐term cycling stability, with a capacity decay of 0.046% per cycle over 1000 cycles, even at 2 C. Noteworthy, under a sulfur loading up to 6 mg cm−2, a high reversible areal capacity of 5.3 mAh cm−2 can be achieved after 50 cycles at 0.1 C. The heterostructure‐modified S cathode effectively reconciles the thermodynamic and kinetic characteristics of LiPSs for adsorption and conversion, furthering the development of high‐performance Li–S batteries.
Experimental measurements and theoretical calculations show that the Ni‐CeO2 heterostructure combines the strong adoption of LiPSs with excellent catalytic activity for accelerating the redox kinetics between S8 and Li2S. The present study provides an effective strategy for accommodating the thermodynamic and kinetic characteristics of LiPSs adsorption and conversion.The material prepared in this study has considerable application potential in high‐performance Li‐S batteries.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Cubic phase garnet-type Li7La3Zr2O12 (LLZO) is a promising solid electrolyte for highly safe Li-ion batteries. Al-doped LLZO (Al-LLZO) has been widely studied due to the low cost of Al2O3. The ...reported ionic conductivities were variable due to the complicated Al3+-Li+ substitution and LixAlOy segregation in Al-LLZO ceramics. This work prepared Li7−3xAlxLa3Zr2O12 (x = 0.00~0.40) ceramics via a conventional solid-state reaction method. The AC impedance and corresponding distribution of relaxation times (DRT) were analyzed combined with phase transformation, cross-sectional microstructure evolution, and grain boundary element mapping results for these Al-LLZO ceramics to understand the various ionic transportation levels in LLZO with different Al-doping amounts. The low conductivity in low Al-doped (0.12~0.28) LLZO originates from the slow Li+ ion migration (1.4~0.25 μs) in the cubic-tetragonal mixed phase. On the other hand, LiAlO2 and LaAlO3 segregation occur at the grain boundaries of high Al-doped (0.40) LLZO, resulting in a gradual Li+ ion jump (6.5 μs) over grain boundaries and low ionic conductivity. The Li6.04Al0.32La3Zr2O12 ceramic delivers the optimum Li+ ion conductivity of 1.7 × 10−4 S cm−1 at 25 °C.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A novel and efficient 3D biohybrid photocatalyst, defective MoS2 nanosheets encapsulated carbonized rape pollen, was fabricated and applied to water disinfection. The rape pollen-MoS2 (PM) biohybrid ...showed excellent dispersibility, high stability, and efficient charge-carrier separation and migration ability, resulting in the highly enhanced photocatalytic inactivation performance toward various waterborne bacteria under different light sources. The inactivation mechanisms were systematically investigated. Reactive species (RSs), including electrons, holes, and reactive oxygen species (•O2 – and •OH), played major roles in inactivating bacteria. The antioxidant system of bacteria exhibited a self-protection capacity by eliminating the photogenerated RSs from PM biohybrid at the early stage of inactivation. With the accumulation of RSs, the cell membrane and membrane-associated functions were destroyed, as suggested by the collapse of cell envelope and subsequent loss of cell respiration and ATP synthesis capacity. The microscopic images further confirmed the destruction of the bacterial membrane. After losing the membrane barrier, the oxidation of cytoplasmic proteins and lipids caused by invaded RSs occurred readily. Finally, the leakage of DNA and RNA announced the irreversible death of bacteria. These results indicated that the bacterial inactivation began with the membrane rupture, followed by the oxidation and leakage of intracellular substances. This work not only provided a new insight into the combination of semiconductors with earth-abundant biomaterials for fabricating high-performance photocatalysts, but also revealed the underlying mechanisms of photocatalytic bacterial inactivation in depth.
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IJS, KILJ, NUK, PNG, UL, UM
To bridge the gap between laboratory research and commercial applications, it is vital to develop scalable methods to produce large quantities of high-quality and solution-processable few-layer ...phosphorene (FLBP). Here, we report an ultrafast cathodic expansion (in minutes) of bulk black phosphorus in the nonaqueous electrolyte of tetraalkylammonium salts that allows for the high-yield (>80%) synthesis of nonoxidative few-layer BP flakes with high crystallinity in ambient conditions. Our detailed mechanistic studies reveal that cathodic intercalation and subsequent decomposition of solvated cations result in the ultrafast expansion of BP toward the high-yield production of FLBP. The FLBPs thus obtained show negligible structural deterioration, excellent electronic properties, great solution processability, and high air stability, which allows us to prepare stable BP inks (2 mg/mL) in low-boiling point solvents for large-area inkjet printing and fabrication of optoelectronic devices.
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IJS, KILJ, NUK, PNG, UL, UM
Molybdenum trioxide (MoO3) suffers from poor conductivity, a low rate capability, and unsatisfactory cycling stability in lithium‐ion batteries. The aliovalent ion doping may present an effective way ...to improve the electrochemical performances of MoO3. Here, it is shown, by first‐principle calculations, that doping MoO3 with V by 12.5% can modulate significantly electronic structure and provide a small diffusion barrier for enhancing the electrochemical performance of MoO3. The ultralong Mo0.88V0.12O2.94 nanostructures, which retain the h‐MoO3 structure and present an exceptionally high conductivity and fast ionic diffusion due to the substitution of V, facilitating lithiation/delithiation behavior, and induce a fine nanosized structure with a reduced volume change are prepared. As a result, the stress and strain are alleviated during the Li‐ion intercalation/deintercalation processes, improving the cycling stability and rate capability. Such a large improvement in the electrochemical properties can be ascribed to the stabilizing effect of V, the small migration energy barrier, and short diffusion path, which arise from the introduction of V into MoO3. The unique engineering strategy and facile synthesis route open up a new avenue in modifying and developing other species of electrode materials.
The fabrication of mixed Mo‐V oxides, according to theoretical calculations and experimental approaches, has a unique electronic structure and small diffusion barrier, leading to a more superior electrochemical performance compared to that of molybdenum oxides. In addition, the unique engineering strategy and facile synthesis route establish new avenues for the modification and construction of other electrode materials.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Highlights
Divalent magnesium ions as electrolyte additives are first used to improve the performance of vanadium-based cathodes for aqueous ZIBs.
Pre-adding magnesium ions into electrolytes provide ...an appropriate equilibrium balance between the dissolution and recombination of magnesium vanadates, thus suppress the continuous dissolution of active materials, and lead to a higher stability of the electrode.
The hybrid aqueous electrolytes with cost-effective ZnSO
4
and MgSO
4
salts show a better competitive prospective for the stationary grid-scale applications.
MgSO
4
is chosen as an additive to address the capacity fading issue in the rechargeable zinc-ion battery system of Mg
x
V
2
O
5
·nH
2
O//ZnSO
4
//zinc. Electrolytes with different concentration ratios of ZnSO
4
and MgSO
4
are investigated. The batteries measured in the 1 M ZnSO
4
−1
M MgSO
4
electrolyte outplay other competitors, which deliver a high specific capacity of 374 mAh g
−1
at a current density of 100 mA g
−1
and exhibit a competitive rate performance with the reversible capacity of 175 mAh g
−1
at 5 A g
−1
. This study provides a promising route to improve the performance of vanadium-based cathodes for aqueous zinc-ion batteries with electrolyte optimization in cost-effective electrolytes.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
One key challenge facing room temperature Na-ion batteries lies in identifying earth-abundant, environmentally friendly and safe materials that can provide efficient Na+ storage sites in Na-ion ...batteries. Herein, we report such a material, polyoxometalate Na2H8MnV13O38 (NMV), with entirely different composition and structure from those cathode compounds reported before. Ex-situ XPS and FTIR analyses reveal that NMV cathode behaves like an “electron/Na-ion sponge”, with 11 electrons/Na+ acceptability per mole, which has a decisive contribution to the high capacity. The extraordinary structural features, evidenced by X-ray crystallographic analysis, of Na2H8MnV13O38 with a flexible 2D lamellar network and 1D open channels provide diverse Na ion migration pathways, yielding good rate capability. First-principle calculations demonstrate that a super-reduced state, MnV13O3820−, is formed with slightly expanded size (ca. 7.5%) upon Na+ insertion compared to the original MnV13O389–. This “ion sponge” feature ensures the good cycling stability. Consequently, benefiting from the combinations of “electron/ion sponge” with diverse Na+ diffusion channels, when revealed as the cathode materials for Na-ion batteries, Na2H8MnV13O38/G exhibits a high specific capacity (ca. 190 mA h/g at 0.1 C), associates with a good rate capability (130 mA h/g at 1 C), and a good capacity retention (81% at 0.2 C). Our results promote better understanding of the storage mechanism in polyoxometalate host, enrich the existing rechargeable SIBs cathode chemistry, and enlighten an exciting direction for exploring promising cathode materials for Na-ion batteries.
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IJS, KILJ, NUK, PNG, UL, UM
A novel efficient method is proposed to synthesize a large amount of Li
PS
Cl
precursor in only 5 minutes with a conductivity of 20 mS cm
after sintering, which can replace the common ball-milling ...method. The ASSBs show excellent electrochemical performance with high loading (20 mg cm
) and great capacity retention (80% after 200 cycles). This is important for the industrial production of sulfide solid electrolytes for fabricating Ah-level ASSBs.
Abstract
Deuterium labeling is of great value in organic synthesis and the pharmaceutical industry. However, the state-of-the-art C–H/C–D exchange using noble metal catalysts or strong bases/acids ...suffers from poor functional group tolerances, poor selectivity and lack of scope for generating molecular complexity. Herein, we demonstrate the deuteration of halides using heavy water as the deuteration reagent and porous CdSe nanosheets as the catalyst. The deuteration mechanism involves the generation of highly active carbon and deuterium radicals via photoinduced electron transfer from CdSe to the substrates, followed by tandem radicals coupling process, which is mechanistically distinct from the traditional methods involving deuterium cations or anions. Our deuteration strategy shows better selectivity and functional group tolerances than current C–H/C–D exchange methods. Extending the synthetic scope, deuterated boronic acids, halides, alkynes, and aldehydes can be used as synthons in Suzuki coupling, Click reaction, C–H bond insertion reaction etc. for the synthesis of complex deuterated molecules.
The development of organic molecule-based batteries is hampered by stability issues caused by the dissolution of the active organic materials in electrolytes. Herein, phenazine (PNZ) and ...2,3-diaminophenazine (DAP) are investigated as organic electrode materials. The presence of amino functional groups in DAP dramatically enhances its electrochemical performances due to suppressed dissolution in the electrolyte.
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