Rechargeable Li/Cl2 Battery Down to -80 °C

Low temperature rechargeable batteries are important to life in cold climates, polar/deep-sea expeditions, and space explorations. Here, this work reports 3.5-4 V rechargeable lithium/chlorine (Li/Cl2 ) batteries operating down to -80 °C, employing Li metal negative electrode, a novel carbon dioxide (CO2 ) activated porous carbon (KJCO2 ) as the positive electrode, and a high ionic conductivity (≈5-20 mS cm-1 from -80 °C to room-temperature) electrolyte comprised of aluminum chloride (AlCl3 ), lithium chloride (LiCl), and lithium bis(fluorosulfonyl)imide (LiFSI) in low-melting-point (-104.5 °C) thionyl chloride (SOCl2 ). Between room-temperature and -80 °C, the Li/Cl2 battery delivers up to ≈29 100-4500 mAh g-1 first discharge capacity (based on carbon mass) and a 1200-5000 mAh g-1 reversible capacity over up to 130 charge-discharge cycles. Mass spectrometry and X-ray photoelectron spectroscopy probe Cl2 trapped in the porous carbon upon LiCl electro-oxidation during charging. At -80 °C, Cl2 /SCl2 /S2 Cl2 generated by electro-oxidation in the charging step are trapped in porous KJCO2 carbon, allowing for reversible reduction to afford a high discharge voltage plateau near ≈4 V with up to ≈1000 mAh g-1 capacity for SCl2 /S2 Cl2 reduction and up to ≈4000 mAh g-1 capacity at ≈3.1 V plateau for Cl2 reduction.

Copper nanoparticles embedded fungal chitosan as a rational and sustainable bionanozyme with robust laccase activity for catalytic oxidation of phenolic pollutants

Despite their potential for oxidation of persistent environmental pollutants, the development of rational and sustainable laccase nanozymes with efficient catalytic performance remains a challenge. Herein, fungal-produced chitosan-copper (CsCu) is proposed as a rational and sustainable bionanozyme with intrinsic laccase activity. The CsCu nanozyme was prepared by in situ reduction of copper on chitosan extracted from Irpex sp. isolate AWK2 a native fungus, from traditional fermented foods, yielding a low molecular weight chitosan with a 70% degree of deacetylation. Characterizations of the nanozyme using SEM-EDX, XRD, and XPS confirmed the presence of a multi-oxidation state copper on the chitosan matrix which is consistent with the composition of natural laccase. The laccase memetic activity was investigated using 2,4-DP as a substrate which oxidized to form a reddish-pink color with 4-AP (λmax = 510 nm). The CsCu nanozyme showed 38% higher laccase activity than the pristine Cu NPs at pH 9, indicating enhanced activity in the presence of chitosan structure. Further, CsCu showed significant stability in harsh conditions and exhibited a lower Km (0.26 mM) which is competitive with that reported for natural laccase. Notably, the nanozyme converted 92% of different phenolic substrates in 5 h, signifying a robust performance for environmental remediation purposes.

Shedding light on rechargeable Na/Cl2 battery

Advancing new ideas of rechargeable batteries represents an important path to meeting the ever-increasing energy storage needs. Recently, we showed rechargeable sodium/chlorine (Na/Cl2) (or lithium/chlorine Li/Cl2) batteries that used a Na (or Li) metal negative electrode, a microporous amorphous carbon nanosphere (aCNS) positive electrode, and an electrolyte containing dissolved aluminum chloride and fluoride additives in thionyl chloride [G. Zhu et al., Nature 596, 525-530 (2021) and G. Zhu et al., J. Am. Chem. Soc. 144, 22505-22513 (2022)]. The main battery redox reaction involved conversion between NaCl and Cl2 trapped in the carbon positive electrode, delivering a cyclable capacity of up to 1,200 mAh g-1 (based on positive electrode mass) at a ~3.5 V discharge voltage [G. Zhu et al., Nature 596, 525-530 (2021) and G. Zhu et al., J. Am. Chem. Soc. 144, 22505-22513 (2022)]. Here, we identified by X-ray photoelectron spectroscopy (XPS) that upon charging a Na/Cl2 battery, chlorination of carbon in the positive electrode occurred to form carbon-chlorine (C-Cl) accompanied by molecular Cl2 infiltrating the porous aCNS, consistent with Cl2 probed by mass spectrometry. Synchrotron X-ray diffraction observed the development of graphitic ordering in the initially amorphous aCNS under battery charging when the carbon matrix was oxidized/chlorinated and infiltrated with Cl2. The C-Cl, Cl2 species and graphitic ordering were reversible upon discharge, accompanied by NaCl formation. The results revealed redox conversion between NaCl and Cl2, reversible graphitic ordering/amorphourization of carbon through battery charge/discharge, and probed trapped Cl2 in porous carbon by XPS.

High-Capacity Rechargeable Li/Cl2 Batteries with Graphite Positive Electrodes

Developing new types of high-capacity and high-energy density rechargeable batteries is important to future generations of consumer electronics, electric vehicles, and mass energy storage applications. Recently, we reported ∼3.5 V sodium/chlorine (Na/Cl₂) and lithium/chlorine (Li/Cl₂) batteries with up to 1200 mAh g^-1 reversible capacity, using either a Na or a Li metal as the negative electrode, an amorphous carbon nanosphere (aCNS) as the positive electrode, and aluminum chloride (AlCl₃) dissolved in thionyl chloride (SOCl₂) with fluoride-based additives as the electrolyte [Zhu et al., Nature, 2021, 596 (7873), 525-530]. The high surface area and large pore volume of aCNS in the positive electrode facilitated NaCl or LiCl deposition and trapping of Cl₂ for reversible NaCl/Cl₂ or LiCl/Cl₂ redox reactions and battery discharge/charge cycling. Here, we report an initially low surface area/porosity graphite (DGr) material as the positive electrode in a Li/Cl₂ battery, attaining high battery performance after activation in carbon dioxide (CO₂) at 1000 °C (DGr_ac) with the first discharge capacity ∼1910 mAh g^-1 and a cycling capacity up to 1200 mAh g^-1. Ex situ Raman spectroscopy and X-ray diffraction (XRD) revealed the evolution of graphite over battery cycling, including intercalation/deintercalation and exfoliation that generated sufficient pores for hosting LiCl/Cl₂ redox. This work opens up widely available, low-cost graphitic materials for high-capacity alkali metal/Cl₂ batteries. Lastly, we employed mass spectrometry to probe the Cl₂ trapped in the graphitic positive electrode, shedding light into the Li/Cl₂ battery operation.

A Nonflammable High-Voltage 4.7 V Anode-Free Lithium Battery

Anode-free lithium-metal batteries employ in situ lithium-plated current collectors as negative electrodes to afford optimal mass and volumetric energy densities. The main challenges to such batteries include their poor cycling stability and the safety issues of the flammable organic electrolytes. Here, a high-voltage 4.7 V anode-free lithium-metal battery is reported, which uses a Cu foil coated with a layer (≈950 nm) of silicon-polyacrylonitrile (Si-PAN, 25.5 µg cm^-2 ) as the negative electrode, a high-voltage cobalt-free LiNi_0.5 Mn_1.5 O₄ (LNMO) as the positive electrode and a safe, nonflammable ionic liquid electrolyte composed of 4.5 m lithium bis(fluorosulfonyl)imide (LiFSI) salt in N-methyl-N-propyl pyrrolidiniumbis(fluorosulfonyl)imide (Py₁₃ FSI) with 1 wt% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as additive. The Si-PAN coating is found to seed the growth of lithium during charging, and reversibly expand/shrink during lithium plating/stripping over battery cycling. The wide-voltage-window electrolyte containing a high concentration of FSI^- and TFSI^- facilitates the formation of stable solid-electrolyte interphase, affording a 4.7 V anode-free Cu@Si-PAN/LiNi_0.5 Mn_1.5 O₄ battery with a reversible specific capacity of ≈120 mAh g^-1 and high cycling stability (80% capacity retention after 120 cycles). These results represent the first anode-free Li battery with a high 4.7 V discharge voltage and high safety.

Sensitive and reliable detection of deoxynivalenol mycotoxin in pig feed by surface enhanced Raman spectroscopy on silver nanocubes@polydopamine substrate

Deoxynivalenol (DON) is one of the trichothecene mycotoxin, a frequent contaminant of pig feed. Surface-enhanced Raman spectroscopy (SERS) is a fast and ultrasensitive analytical tool for point-of-need applications to identify molecular fingerprint structures at low concentrations. However, the use of SERS for analyte detection with flexible and robust structures is still challenging. Herein, we have developed core-shell silver nanocubes coated with polydopamine (Ag NCs@PDA) SERS substrate for the quantitative detection of deoxynivalenol in pig feed. The Ag NCs@PDA substrate with ultrathin (1.6 nm) PDA shell thickness enhances the absorption of DON via hydrogen bonding and π-π stacking interactions, as well as improves the stability of the substrate. The results of the SERS showed a high analytical enhancement factor (AEF) of 1.82 × 10⁷ and a detection limit (LOD) as low as femtomolar range (0.82 fM). The LOD of the Ag NCs@PDA substrate for DON detection is 1.8 times lower than the bare Ag NCs. Furthermore, the Ag NCs@PDA substrate is stable which retains 88.24% of the original Raman intensity after storage for three months. The obtained results demonstrate that the Ag NCs@PDA substrates can realize label-free detection of deoxynivalenol mycotoxin with high sensitivity, reproducibility, and stability. Our work proposes a low-cost method for the designing of the SERS sensing device, and has great potential to be applied in food safety, biomedical sciences, and environmental monitoring.

Hierarchical 3D Architectured Ag Nanowires Shelled with NiMn-Layered Double Hydroxide as an Efficient Bifunctional Oxygen Electrocatalyst

Herein, we report hierarchical 3D NiMn-layered double hydroxide (NiMn-LDHs) shells grown on conductive silver nanowire (Ag NWs) cores as efficient, low-cost, and durable oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional electrocatalysts for metal-air batteries. The hierarchical 3D architectured Ag NW@NiMn-LDH catalysts exhibit superb OER/ORR activities in alkaline conditions. The outstanding bifunctional activities of Ag NW@NiMn-LDHs are essentially attributed to increasing both site activity and site populations. The synergistic contributions from the hierarchical 3D open-pore structure of the LDH shells, improved electrical conductivity, and small thickness of the LDHs shells are associated with more accessible site populations. Moreover, the charge transfer between Ag cores and metals of LDH shells and the formation of defective and distorted sites (less coordinated Ni and Mn sites) strongly enhance the site activity. Thus, Ag NW@NiMn-LDH hybrids exhibit a 0.75 V overvoltage difference between ORR and OER with excellent durability for 30 h, demonstrating the distinguished bifunctional electrocatalyst reported to date. Interestingly, the homemade rechargeable Zn-air battery using the hybrid Ag NW@NiMn-LDHs (1:2) catalyst as the air electrode exhibits a charge-discharge voltage gap of ∼0.77 V at 10 mA cm^-2 and shows excellent cycling stability. Thus, the concept of the hierarchical 3D architecture of Ag NW@NiMn-LDHs considerably advances the practice of LDHs toward metal-air batteries and oxygen electrocatalysts.

Dielectric nanosheet modified plasmonic-paper as highly sensitive and stable SERS substrate and its application for pesticides detection

The interaction of plasmonic nanoparticles with a dielectric platform gives rise to unique optical behaviors and this can be maneuvered to improve the plasmonic/SERS performances of a substrate. Herein, dielectric modified plasmonic-paper SERS substrate is developed by assembling Ag@SiO₂ nanocubes on Fe-TiO₂ nanosheets (NS) modified paper. The Fe-TiO₂ NS being visible light responsive significantly alters the optical property of the paper and serves as a dielectric underlay for the Ag nanocubes. Hence, the incident light reflected back from the dielectric nanosheets couples with the scattered light from the Ag nanocubes leading to spatially enhanced electromagnetic field improving the SERS enhancement. The prepared dielectric modified plasmonic-paper has an average enhancement factor (EF) of 1.49 × 10⁷ using R6G as a probe molecule. This value is superior to unmodified plasmonic-paper highlighting the coupling effect of the dielectric nanosheets. The substrate shows robust detection performance for thiabendazole and achieves a limit of detection (LOD) of 19 μg/L, which is 4-fold more sensitive than unmodified plasmonic paper. Direct swabbing test of thiabendazole sprayed apple fruit shows a discernible Raman signal down to 15 ppb indicating the utility of the substrate for point-of-need applications in food safety.

Engineering heterometallic bonding in bimetallic electrocatalysts: towards optimized hydrogen oxidation and evolution reactions

Tuning the type and degree of heterometallic bonding in bimetallic catalysts is crucial to achieving optimal catalytic performance.

Investigation of Sodium Plating and Stripping on a Bare Current Collector with Different Electrolytes and Cycling Protocols

In the present study, stable sodium plating/stripping has been achieved on a bare aluminum current collector, without any surface modifications or artificial SEI deposition. The crucial role of predeposited sodium using cyclic voltammetry on bare aluminum as a matrix for plating/stripping has been highlighted using different protocols for cycling. The predeposition strategy ensures stable and efficient cycling of sodium in anode-free sodium batteries without dendritic formations. The study highlights the difference of sodium plating/stripping in carbonate and glyme solvent electrolytes on the bare aluminum current collector. Contrary to the carbonate solvent electrolyte, the cell with the tetraglyme solvent electrolyte and sodium loading of 1 mA h/cm² has an overpotential under 20 mV during the sodium plating/stripping cycles at 0.5 mA/cm² for a testing period of 650 h. Overpotentials under 40 and 100 mV have been achieved at current densities up to 1 and 2 mA/cm² for loadings up to 5 and 10 mA h/cm², respectively, for a testing time up to 1500 h. Density functional theory simulations have been performed to obtain the solvation energies, and the highest occupied molecular orbital-lowest unoccupied molecular orbital band gap of the solvent-sodium ion complexes for the glyme solvent electrolytes and their trends have been correlated with the experimental observations.

Nucleation and Growth Mechanism of Lithium Metal Electroplating

Understanding the mechanism of Li nucleation and growth is essential for providing long cycle life and safe lithium ion batteries or lithium metal batteries. However, no quantitative report on Li metal deposition is available, to the best of our knowledge. We propose a model for quantitatively understanding the Li nucleation and growth mechanism associated with the solid-electrolyte interphase (SEI) formation, which we name the Li-SEI model. The current transients at various overpotentials initiate the nucleation and growth of Li metal on bare Cu foil. The Li-SEI model considering a three-dimensional diffusion-controlled instantaneous process (J_3D-DC) with the simultaneous reduction of electrolyte decomposition (J_SEI) due to the SEI fracture is employed for investigating the Li nucleation and growth mechanism. The individual contributions of experimental and theoretical transient states, i.e., the fundamental kinetic values of diffusion coefficient (D), rate of nucleation (N₀), and rate constant of electrolyte decomposition (k_SEI), can be determined from the Li-SEI model. Interestingly, J_SEI increases with time, indicating that the current contributing from the electrolyte decomposition increases with time due to the SEI fracture upon Li deposition. Meanwhile, the k_SEI increases with overpotential, indicating the SEI fracture is more serious at higher overpotential or higher growth rate. The k_SEI is smaller in the electrolyte with fluoroethylene carbonate (FEC) additive, indicating that FEC additive can significantly suppress the SEI fracture during Li metal deposition. This proposed model opens a new way to quantitatively understand the Li nucleation and growth mechanism and electrolyte decomposition on various substrates or in different electrolytes.

Effects of Concentrated Salt and Resting Protocol on Solid Electrolyte Interface Formation for Improved Cycle Stability of Anode-Free Lithium Metal Batteries

The combined effect of concentrated electrolyte and cycling protocol on the cyclic performance of the anode-free battery (AFB) is evaluated systematically. In situ deposition of Li in the AFB configuration in the presence of a concentrated electrolyte containing fluorine-donating salt and resting the deposit enables the formation of stable and uniform SEI. The SEI intercepts the undesirable side reaction between the deposit and solvent in the electrolyte and reduces electrolyte and Li consumption during cycling. The synergy between the laboratory-prepared concentrated 3 M LiFSI in the ester-based electrolyte and our resting protocol significantly enhanced cyclic performances of AFBs in comparison to the commercial carbonate-based dilute electrolyte, 1 M LiPF₆. Benefitting from the combined effect, Cu∥LiFePO₄ cells delivered excellent cyclic performance at 0.5 mA/cm² with an average CE of up to 98.78%, retaining a reasonable discharge capacity after 100 cycles. Furthermore, the AFB can also be cycled at a high rate up to 1.0 mA/cm² with a high average CE and retaining the encouraging discharge capacity after 100 cycles. The fast cycling and stable performance of these cells are attributed to the formation of robust, flexible, and tough F-rich conductive SEI on the surface of the in situ-deposited Li by benefiting from the combined effect of the resting protocol and the concentrated electrolyte. A condescending understanding of the mechanism of SEI formation and material choice could facilitate the development of AFBs as future advanced energy storage devices.

Immobilized Single Molecular Molybdenum Disulfide on Carbonized Polyacrylonitrile for Hydrogen Evolution Reaction

Designing a MoS₂ catalyst having a large number of active sites and high site activity enables the catalytic activity toward the hydrogen evolution reaction to be improved. Herein, we report the synthesis of a low-cost and catalytically active immobilized single molecular molybdenum disulfide on carbonized polyacrylonitrile (MoS₂-cPAN) electrocatalyst. From the extended X-ray absorption fine structure spectra analysis, we found that the as-prepared material has no metal-metal scattering and it resembles MoS₂ with a molecular state. Meanwhile, the size of the molecular MoS₂ has been estimated to be about 1.31 nm by high-angle annular dark-field scanning transmission electron microscopy. A low coordination number and maximum utilization of the single molecular MoS₂ surface enable MoS₂-cPAN to demonstrate electrochemical performance significantly better than that of bulk MoS₂ by two orders of exchange current density ( j_o) and turnover frequency to the hydrogen evolution.

Locally Concentrated LiPF6 in a Carbonate-Based Electrolyte with Fluoroethylene Carbonate as a Diluent for Anode-Free Lithium Metal Batteries

Currently, concentrated electrolyte solutions are attracting special attention because of their unique characteristics such as unusually improved oxidative stability on both the cathode and anode sides, the absence of free solvent, the presence of more anion content, and the improved availability of Li⁺ ions. Most of the concentrated electrolytes reported are lithium bis(fluorosulfonyl)imide (LiFSI) salt with ether-based solvents because of the high solubility of salts in ether-based solvents. However, their poor anti-oxidation capability hindered their application especially with high potential cathode materials (>4.0 V). In addition, the salt is very costly, so it is not feasible from the cost analysis point of view. Therefore, here we report a locally concentrated electrolyte, 2 M LiPF₆, in ethylene carbonate/diethyl carbonate (1:1 v/v ratio) diluted with fluoroethylene carbonate (FEC), which is stable within a wide potential range (2.5-4.5 V). It shows significant improvement in cycling stability of lithium with an average Coulombic efficiency (ACE) of ∼98% and small voltage hysteresis (∼30 mV) with a current density of 0.2 mA/cm² for over 1066 h in Li||Cu cells. Furthermore, we ascertained the compatibility of the electrolyte for anode-free Li-metal batteries (AFLMBs) using Cu||LiNi_1/3Mn_1/3Co_1/3O₂ (NMC, ∼2 mA h/cm²) with a current density of 0.2 mA/cm². It shows stable cyclic performance with ACE of 97.8 and 40% retention capacity at the 50th cycle, which is the best result reported for carbonate-based solvents with AFLMBs. However, the commercial carbonate-based electrolyte has <90% ACE and even cannot proceed more than 15 cycles with retention capacity >40%. The enhanced cycle life and well retained in capacity of the locally concentrated electrolyte is mainly because of the synergetic effect of FEC as the diluent to increase the ionic conductivity and form stable anion-derived solid electrolyte interphase. The locally concentrated electrolyte also shows high robustness to the effect of upper limit cutoff voltage.

Ultrafast x-ray absorption near edge spectroscopy of Fe3O4 using a laboratory based femtosecond x-ray source

Ultrafast time-resolved x-ray absorption near edge spectroscopy (XANES) experiment was performed on a magnetite (Fe₃O₄) film using a femtosecond laser plasma x-ray source delivering Bremsstrahlung radiation. Ultrafast temporal evolution of the XANES of Fe₃O₄ following an excitation by an infra-red (IR) laser pulse was observed in a pump-probe scheme. The Fe K x-ray absorption edge shifts towards low energy upon IR excitation as much as 12 eV, which is mainly attributed to the charge transfer between the Fe ions. The shift in the absorption edge occurred within about 150 fs, typical time of non-thermal electronic redistribution. The charge transfer also causes an ultrafast increase in the IR transmission in the similar time scale.

Multilayer-graphene-stabilized lithium deposition for anode-Free lithium-metal batteries

The will to circumvent capacity fading, Li dendrite formation, and low coulombic efficiency in anode-free Li-metal batteries (AFLMBs) requires a radical change in the science underpinning new materials discovery, battery design, and understanding electrode interfaces. Herein, a Cu current collector formed with ultrathin multilayer graphene grown via chemical vapor deposition (CVD) was used as an artificial layer to stabilize the electrode interface and sandwich-deposited Li with Cu. A multilayer graphene film's superior strength, chemical stability, and flexibility make it an excellent choice to modify a Cu electrode. Fabricating an anode bigger than the cathode improved the alignment of the electrodes during assembly, minimizing interfacial stress. Here, 19 mm electrodes when paired with a commercial LiFePO4 cathode (mass loading: ∼12 mg cm-2) delivered the first-cycle discharge capacities of 147 and 151 mA h g-1 for bare and multilayer-graphene-protected electrodes, respectively, which could alleviate the big hurdle (initial capacity loss) in anode-free batteries. After 100 round-trip cycles, bare Cu and multilayer-graphene-protected electrodes retained ∼46 and ∼61% of their initial capacities, respectively, in an ether-based electrolyte at the rate of 0.1 C.

Rechargeable aluminum batteries: effects of cations in ionic liquid electrolytes

Room temperature ionic liquids (RTILs) are solvent-free liquids comprised of densely packed cations and anions. The low vapor pressure and low flammability make ILs interesting for electrolytes in batteries. In this work, a new class of ionic liquids were formed for rechargeable aluminum/graphite battery electrolytes by mixing 1-methyl-1-propylpyrrolidinium chloride (Py13Cl) with various ratios of aluminum chloride (AlCl₃) (AlCl₃/Py13Cl molar ratio = 1.4 to 1.7). Fundamental properties of the ionic liquids, including density, viscosity, conductivity, anion concentrations and electrolyte ion percent were investigated and compared with the previously investigated 1-ethyl-3-methylimidazolium chloride (EMIC-AlCl₃) ionic liquids. The results showed that the Py13Cl–AlCl₃ ionic liquid exhibited lower density, higher viscosity and lower conductivity than its EMIC-AlCl₃ counterpart. We devised a Raman scattering spectroscopy method probing ILs over a Si substrate, and by using the Si Raman scattering peak for normalization, we quantified speciation including AlCl₄⁻, Al₂Cl₇⁻, and larger AlCl₃ related species with the general formula (AlCl₃)_n in different IL electrolytes. We found that larger (AlCl₃)_n species existed only in the Py13Cl–AlCl₃ system. We propose that the larger cationic size of Py13⁺ (142 ų) versus EMI⁺ (118 ų) dictated the differences in the chemical and physical properties of the two ionic liquids. Both ionic liquids were used as electrolytes for aluminum–graphite batteries, with the performances of batteries compared. The chloroaluminate anion-graphite charging capacity and cycling stability of the two batteries were similar. The Py13Cl–AlCl₃ based battery showed a slightly larger overpotential than EMIC-AlCl₃, leading to lower energy efficiency resulting from higher viscosity and lower conductivity. The results here provide fundamental insights into ionic liquid electrolyte design for optimal battery performance.

Room temperature ionic liquids (RTILs) are solvent-free liquids comprised of densely packed cations and anions. Properties of Py13Cl–AlCl₃ ILs were studied and compared with EMIC-AlCl₃ ILs for use as electrolyte in Al–graphite battery.

Nanostructured Ti07Mo0₃O₂ as Efficient Non-Carbon Support for PtRu Catalysts in Direct Methanol Fuel Cells

This study was focused on a new strategy by investigating whether the novel Ti0.7Mo0.3O2 material can be used as a conductive support for PtRu to prevent carbon corrosion and improve catalyst activity as the novel Ti0.7Mo0.3O2 support has some functional advantages. The 30 wt% PtRu/Ti0.7Mo0.3O2 catalyst showed the highest current density at the complete potential, which is approximately 12-fold and 1.4-fold higher than that of the commercial 20 wt% Pt/C (E-TEK) and 30 wt% PtRu/C (JM) catalysts, respectively, at 0.6 V (NHE) toward the methanol oxidation (MOR). Our data suggest that this enhancement is a result of the electronic Pt structure change upon its synergistic interaction with Ti0.7Mo0.3O2 support and the improved mass transport kinetics of PtRu/Ti0.7Mo0.3O2 compared to the carbon support (Pt or PtRu). The PtRu/Ti0.7Mo0.3O2 catalyst exhibited a much higher stability than carbon-supported catalysts because of the strong metal/support interactions between the Pt particles and Ti0.7Mo0.3O2, the inherent structural and chemical stability, and the corrosion resistance of the Ti0.7Mo0.3O2 in acidic and oxidative environments.

One-Dimensional Cu2- xSe Nanorods as the Cathode Material for High-Performance Aluminum-Ion Battery

In this work, nonstoichiometric Cu_{2- x}Se fabricated by a facile water evaporation process is used as high-performance Al-ion battery cathode materials. Cu_{2- x}Se electrodes show high reversible capacity and excellent cycling stability, even at a high current density of 200 mA g^-1, the specific charge capacity in the initial cycle is 241 mA h g^-1 and maintains 100 mA h g^-1 after 100 cycles with a Coulombic efficiency of 96.1%, showing good capacity retention. The prominent kinetics of Cu_{2- x}Se electrodes is also revealed by the GITT, which is attributed to the ultrahigh electronic conductivity of the Cu_{2- x}Se material. Most importantly, an extensive research is dedicated to investigating the detailed intercalation and de-intercalation of relatively large chloroaluminate anions into the cubic Cu_{2- x}Se, which is conducive to better understand the reaction mechanism of the Al/Cu_{2- x}Se battery.

Investigation of the Na Storage Property of One-Dimensional Cu2- xSe Nanorods

In this study, one-dimensional Cu_{2- x}Se nanorods synthesized by a simple water evaporation-induced self-assembly approach are served as the anode material for Na-ion batteries for the first time. Cu_{2- x}Se electrodes express outstanding electrochemical properties. The initial discharge capacity is 149.3 mA h g^-1 at a current density of 100 mA g^-1, and the discharge capacity can remain at 106.2 mA h g^-1 after 400 cycles. Even at a high current density of 2000 mA g^-1, the discharge capacity of the Cu_{2- x}Se electrode still remains at 62.8 mA h g^-1, showing excellent rate performance. Owing to the excellent electronic conductivity and one-dimensional structure of Cu_{2- x}Se, the Cu_{2- x}Se electrodes manifest fast Na⁺ ion diffusion rate. Moreover, detailed Na⁺ insertion/extraction mechanism is further investigated by ex situ measurements and theoretical calculations.

Polyethylene oxide film coating enhances lithium cycling efficiency of an anode-free lithium-metal battery

The practical implementation of an anode-free lithium-metal battery with promising high capacity is hampered by dendrite formation and low coulombic efficiency. Most notably, these challenges stem from non-uniform lithium plating and unstable SEI layer formation on the bare copper electrode. Herein, we revealed the homogeneous deposition of lithium and effective suppression of dendrite formation using a copper electrode coated with a polyethylene oxide (PEO) film in an electrolyte comprising 1 M LiTFSI, DME/DOL (1/1, v/v) and 2 wt% LiNO3. More importantly, the PEO film coating promoted the formation of a thin and robust SEI layer film by hosting lithium and regulating the inevitable reaction of lithium with the electrolyte. The modified electrode exhibited stable cycling of lithium with an average coulombic efficiency of ∼100% over 200 cycles and low voltage hysteresis (∼30 mV) at a current density of 0.5 mA cm-2. Moreover, we tested the anode-free battery experimentally by integrating it with an LiFePO4 cathode into a full-cell configuration (Cu@PEO/LiFePO4). The new cell demonstrated stable cycling with an average coulombic efficiency of 98.6% and capacity retention of 30% in the 200th cycle at a rate of 0.2C. These impressive enhancements in cycle life and capacity retention result from the synergy of the PEO film coating, high electrode-electrolyte interface compatibility, stable polar oligomer formation from the reduction of 1,3-dioxolane and the generation of SEI-stabilizing nitrite and nitride upon lithium nitrate reduction. Our result opens up a new route to realize anode-free batteries by modifying the copper anode with PEO to achieve ever more demanding yet safe interfacial chemistry and control of dendrite formation.

Directly Coating a Multifunctional Interlayer on the Cathode via Electrospinning for Advanced Lithium-Sulfur Batteries

The lithium-sulfur battery is considered as a prospective candidate for a high-energy-storage system because of its high theoretical specific capacity and energy. However, the dissolution and shutter of polysulfides lead to low active material utilization and fast capacity fading. Electrospinning technology is employed to directly coat an interlayer composed of polyacrylonitrile (PAN) and nitrogen-doped carbon black (NC) fibers on the cathode. Benefiting from electrospinning technology, the PAN-NC fibers possess good electrolyte infiltration for fast lithium-ion transport and great flexibility for adhering on the cathode. The NC particles provide good affinity for polysufides and great conductivity. Thus, the polysulfides can be trapped on the cathode and reutilized well. As a result, the PAN-NC-coated sulfur cathode (PAN-NC@cathode) exhibits the initial discharge capacity of 1279 mAh g^-1 and maintains the reversible capacity of 1030 mAh g^-1 with capacity fading of 0.05% per cycle at 200 mA g^-1 after 100 cycles. Adopting electrospinning to directly form fibers on the cathode shows a promising application.

A Plasmonic Coupling Substrate Based on Sandwich Structure of Ultrathin Silica-Coated Silver Nanocubes and Flower-Like Alumina-Coated Etched Aluminum for Sensitive Detection of Biomarkers in Urine

Interactions between substrate and plasmonic nanostructures can give rise to unique optical properties and influence performance in plasmonic biosensing applications. In this study, a substrate with low refractive index and roughness based on flower-like alumina-coated etched aluminum foil (f-Al₂ O₃ /e-Al) has been fabricated. Silver@silica (Ag@SiO₂ ) nanocubes (NCs) assemble in an edge-edge configuration when deposited on this substrate. The rough surface texture of f-Al₂ O₃ /e-Al provides a pathway for coupling of incident light to surface plasmons. The Ag@SiO₂ /f-Al₂ O₃ /e-Al substrate exhibits a coupling efficiency of laser light sources into surface plasmon hotspots for both surface-enhanced Raman scattering (SERS) and metal-enhanced photoluminescence (MEPL). Moreover, the shelf life of this substrate is significantly improved due to a reduction in oxygen diffusion rate mediated by the ultrathin silica spacer and the flower-like Al₂ O₃ dielectric layer. Creatinine and flavin adenine dinucleotide are biomolecules present in human blood and urine. With advanced label-free SERS and MEPL techniques, it is possible to detect these biomarkers in urine, allowing cheap, noninvasive, yet sensitive analysis. The approach explored in this work can be developed into a powerful encoding tool for high-throughput bioanalysis.

Highly sensitive and stable Ag@SiO2 nanocubes for label-free SERS-photoluminescence detection of biomolecules

Surface-enhanced Raman scattering (SERS) and fluorescence microscopy are a widely used biological and chemical characterization techniques. However, the peak overlapping in multiplexed experiments and rapid photobleaching of fluorescent organic dyes is still the limitations. When compared to Ag nanocubes (NCs), higher SERS sensitivities can be obtained with thin shelled silica Ag@SiO₂ NCs, in contrast metal-enhanced photoluminescence (MEPL) is only found with NCs that have thicker silica shells. A 'dual functionality' represented by the simultaneous strengthening of SERS and MEPL signals can be achieved by mixing Ag@SiO₂ NCs, with a silica shell thickness of ~1.5nm and ~4.4nm. This approach allows both the Ag@SiO₂ NCs SERS and MEPL sensitivities to be maintained at ~90% after 12weeks of storage. Based on the distinguished detection of creatinine and flavin adenine dinucleotide in the mixture, the integration of SERS and MEPL together on a stable single plasmonic nanoparticle platform offers an opportunity to enhance both biomarker detection sensitivity and specificity.

Improved Interfacial Properties of MCMB Electrode by 1-(Trimethylsilyl)imidazole as New Electrolyte Additive To Suppress LiPF6 Decomposition

Trace water content in the electrolyte causes the degradation of LiPF₆, and the decomposed products further react with water to produce HF, which alters the surface of anode and cathode. As a result, the reaction of HF and the deposition of decomposed products on electrode surface cause significant capacity fading of cells. Avoiding these phenomena is crucial for lithium ion batteries. Considering the Lewis-base feature of the N-Si bond, 1-(trimethylsilyl)imidazole (1-TMSI) is proposed as a novel water scavenging electrolyte additive to suppress LiPF₆ decomposition. The scavenging ability of 1-TMSI and beneficiary interfacial chemistry between the MCMB electrode and electrolyte are studied through a combination of experiments and density functional theory (DFT) calculations. NMR analysis indicated that LiPF₆ decomposition by water was effectively suppressed in the presence of 0.2 vol % 1-TMSI. XPS surface analysis of MCMB electrode showed that the presence of 1-TMSI reduced deposition of ionic insulating products caused by LiPF₆ decomposition. The results showed that the cells with 1-TMSI additive have better performance than the cell without 1-TMSI by facilitating the formation of solid-electrolyte interphase (SEI) layer with better ionic conductivity. It is hoped that the work can contribute to the understanding of SEI and the development of electrolyte additives for prolonged cycle life with improved performance.

The effect of ligand–ligand interactions on the formation of photoluminescent gold nanoclusters embedded in Au(i)–thiolate supramolecules

Photoluminescence of cysteine-capped gold nanoclusters obtained via the reduction of –[Cys–Au(i)]_n– supramolecules is highly dependent on the degree of supramolecular aggregation.

Sequentially surface modified hematite enables lower applied bias photoelectrochemical water splitting

We achieve a low onset potential of 0.49 V using heavily doped Fe_2−xSn_xO₃surface passivation layer and NiOOH dual surface treatments.

In situ X-ray absorption near edge structure studies and charge transfer kinetics of Na6[V10O28] electrodes

The electron transfer of Na₆[V₁₀O₂₈] was investigated byin situV K-edge X-ray absorption spectroscopy and chronoamperometric experiments for the first time.

3D Graphitic Foams Derived from Chloroaluminate Anion Intercalation for Ultrafast Aluminum-Ion Battery

A 3D graphitic foam vertically aligned graphitic structure and a low density of defects is derived through chloroaluminate anion intercalation of graphite followed by thermal expansion and electrochemical hydrogen evolution. Such aligned graphitic structure affords excellent Al-ion battery characteristics with a discharge capacity of ≈60 mA h g^-1 under a high charge and discharge current density of 12 000 mA g^-1 over ≈4000 cycles.

Using hematite for photoelectrochemical water splitting: a review of current progress and challenges

Photoelectrochemical (PEC) water splitting is a promising technology for solar hydrogen production to build a sustainable, renewable and clean energy economy. Hematite (α-Fe₂O₃) based photoanodes offer promise for such applications, due to their high chemical stability, great abundance and low cost. Despite these promising properties, progress towards the manufacture of practical water splitting devices has been limited. This review is intended to highlight recent advancements and the limitations that still hamper the full utilization of hematite electrodes in PEC water splitting systems. We review recent progress in manipulating hematite for PEC water splitting through various approaches, focused on e.g. enhancing light absorption, water oxidation kinetics, and charge carrier collection efficiency. As the morphology affects various properties, progress in morphological characterization from thicker planar films to recent ultrathin nanophotonic morphologies is also examined. Special emphasis has been given to various ultrathin films and nanophotonic structures which have not been given much attention in previous review articles.

Creation of Electron-doping Liquid Water with Reduced Hydrogen Bonds

The strength of hydrogen bond (HB) decides water's property and activity. Here we propose the mechanisms on creation and persistence of innovatively prepared liquid water, which is treated by Au nanoparticles (AuNPs) under resonant illumination of green-light emitting diode (LED) to create Au NP-treated (sAuNT) water, with weak HB at room temperature. Hot electron transfer on resonantly illuminated AuNPs, which is confirmed from Au LIII-edge X-ray absorption near edge structure (XANES) spectra, is responsible for the creation of negatively charged sAuNT water with the incorporated energy-reduced hot electron. This unique electronic feature makes it stable at least for one week. Compared to deionized (DI) water, the resulting sAuNT water exhibits many distinct properties at room temperature. Examples are its higher activity revealed from its higher vapor pressure and lower specific heat. Furthermore, Mpemba effect can be successfully explained by our purposed hypothesis based on sAuNT water-derived idea of water energy and HB.

Rational design of ethanol steam reforming catalyst based on analysis of Ni/La2O3 metal–support interactions

Ni/La₂O₃ nanocatalyst with strong interactions, compared to Ni/SiO₂, generated higher H₂ yield by suppressing the methanation reaction and coke deposition.