Amorphous Surface Layer Research Articles

Introducing Oxygen Vacancies into a WO3 Photoanode through NaH2PO2 Treatment for Efficient Water Splitting.

WO3, with a high light absorption capacity and a suitable band structure, is considered a promising photoanode material for photoelectrochemical water splitting. However, the poor photoinduced electron-hole separation efficiency limits its application. Herein, we report an effective strategy to suppress electron-hole recombination by introducing oxygen vacancies (OV) on the surface of a WO3 photoanode through NaH2PO2 treatment. An OV-enriched amorphous surface layer with a thickness of 4 nm is formed after NaH2PO2 treatment, which increases the charge carrier density and enlarges the electrochemical surface area of the photoanode. The charge separation and surface injection efficiencies are both improved after NaH2PO2 treatment, and the charge transfer process of the photoanode is accelerated consequently. The current density of the modified WO3 photoanode reaches 0.96 mA cm-2 at 1.23 V.

Simultaneous structure and surface engineering of metal-organic framework derived LiNi0.5-xFe2xMn1.5-xO4 cathode material for improving high voltage performance of lithium-ion batteries

This study presents a novel material synthesis approach utilizing a terephthalic acid-based metal-organic framework as a precursor and employing an ethanol-assisted hydrothermal treatment to produce high-performance Fe-doped LiNi0.5Mn1.5O4 (LNMO) cathode material. This strategy yields a well-crystallized spinel structure with uniformly distributed transition metal ions. Additionally, the appropriate quantity of Fe dopant can achieve the desired Mn3+/Mn4+ ratio, level of structural disordering, and crystal phase purity for Fe-doped LNMO. The synthesis process also aids in forming an amorphous Li2CO3 surface layer, approximately 1 nm thick, which protects the active material from excessive reaction with electrolyte. The typical Fe-doped LNMO cathode (S-05) exhibits superior performance compared to a commercialized LNMO counterpart. It delivers an initial discharge capacity of 135 mAh g-1 at 1 C with exceptional cycling stability over 500 cycles (capacity retention of 90%) under high voltage (5.0 V vs. Li+/Li). Furthermore, its rate capability significantly improves, with a capacity retention of 85% (5 C/0.2 C). This enhanced performance aligns with evidence of activated Ni2+/Ni3+/Ni4+ redox reactions and suppressed cathode electrolyte interphase resistance, leading to promoted Li+ diffusion. Moreover, it is found the cathode helps alleviate electrolyte degradation at high voltages by inhibiting the formation of singlet oxygen in the electrolyte.

Heterophase homojunction construction by amorphous TiOx and N–TiO2 photoanode for oxygen evolution reaction kinetics and charge carriers’ transportation enhancement

Photoelectrochemical (PEC) water splitting by TiO2 photoanode for clean hydrogen production is limited by the poor charge separation and inert oxygen evolution reaction (OER) kinetics issues for now. In this work, a band-matched heterophase homojunction (TiOx/N–TiO2) by amorphous TiOx and N-doped TiO2 nanotube arrays is constructed by two-step anodic oxidation and impregnation. The photocurrent density of TiOx/N–TiO2 reaches 0.69 mA/cm2 at 1.23 V vs. RHE, which is 1.86 folds than bare TiO2. The enhanced charge carriers' injection/separation efficiency, smaller Tafel slope (37.79 mF dec−1) and larger electrochemical active surface area (ECSA) (1.98 mF cm−2) of TiOx/N–TiO2 indicate that N doping and heterophase homojunction with amorphous TiOx effectively facilitate the surface OER kinetics and charge carriers' transportation. TiOx/N–TiO2 is annealed with a transformation of the surface amorphous TiOx layer into anatase TiO2 (a-TiOx/N–TiO2) to study the role of amorphous TiO2 in PEC water splitting. The photocurrent density and applied bias photon-to-current efficiency (ABPE) for a-TiOx/N–TiO2 decrease, even lower than the pristine TiO2. This is due to the reduction of surface oxygen vacancies, which causes the slowdown of OER kinetics and the weakening of charge carrier transportation ability. That is favorable for a better understanding of the OER kinetics and charge carriers’ transportation enhancement mechanism by the surficial modification on the semiconductor during the PEC water splitting.

Nanosecond laser annealing processed surface-structured hyperdoped silicon for efficient near-infrared detection

Surface-structured engineering of hyperdoped silicon can effectively facilitate the absorption of sub-bandgap photons in pristine single-crystal silicon (sc-Si). Here, we conducted different annealing approaches of ordinary thermal annealing (OTA) and nanosecond laser annealing (NLA) on modification of titanium-hyperdoped silicon (Si:Ti) surface structure, to achieve efficient near-infrared detection. It is presented that both OTA and NLA processes can improve the crystallinity of Si:Ti samples. In detail, atomic-resolved STEM characterization illustrates that NLA treatment will further eliminate the amorphous phase on Si:Ti surface to varying degrees. While one-dimensional periodic stacking fault structure of 9R-Si phase is formed at the surface of sc-Si and embedded in the Si matrix during the OTA process, which reveals the seamless interface of 9R-Si/sc-Si along with [11¯0] direction. Due to the high sub-bandgap light absorption and good crystal structure, the Si:Ti photodetector after NLA treatment with an energy density of 2.6 J cm-2exhibited the highest responsivity, reaching 151 mA W-1at 1550 nm even at a low operating voltage of 1 V. We assume the performance enhancement of NLA processed Si:Ti photodetectors can be attributed to two aspects, the one is NLA can reduce the recombination of photo-generated charge carriers in amorphous surface layer by improving crystallization, and the other is that NLA process can weaken the diffusion of titanium impurities due to the extremely rapid heating and cooling rates. This study presents prospects towards surface-structured silicon in infrared light detection.

(Invited) Epitaxial III-V Nanomaterials on the Si Platform for Quantum and Data Communications

As Si-based integrated photonic components begin to replace older technologies for optical data communications, the need for better integration of semiconductor lasers on the Si platform is greater than ever. In addition, emerging interest in integrated-photonic-based quantum computing and quantum sensing presents a further need for quantum light emitters—entangled and single-photon—on Si. III-V quantum dots represent a promising solution, both for the active region of telecommunications-wavelength lasers and for quantum emitters. However, epitaxial quantum dots grown on conventional (100) substrates typically lack the high symmetry required for entangled-photon emission.This presentation will discuss our recent work to develop a novel approach for III-V direct growth on Si via an ultrathin (<10 nm) single crystal strain relieving buffer layer, realized by the selective oxidation and condensation of an amorphous SiGe surface layer. The fabrication and properties of this novel Ge-rich buffer layer, as well as its use for subsequent III-V organometallic vapor-phase epitaxy will be presented.The second part of the talk will present our recent work on the epitaxial growth and characterization of (In,Ga)As quantum dots for the above-mentioned applications. Specifically, I will show that surface-energy-modifying surfactants (Sb, Bi) present the possibility to externally direct quantum dot formation “on-demand” in strained InAs layers on GaAs(111) substrates, where quantum dot formation by the Stranski–Krastanov process does not naturally occur. These nanostructures are prospective for high-symmetry entangled-photon emitters. The three-dimensional (3D) composition profile of InAs quantum dot layers is characterized by atom-probe microscopy (APT), elucidating the real-world quantum dot matrix. This 3D composition data is input into a finite element solver to determine the quantum dot energies and wavefunctions for electrons and holes. The modeling reveals that in high-density quantum dot layers, the electron and hole states are hybridized between multiple quantum dots in the matrix. This has important consequences for design of quantum dot light emitters. The predicted transition energies are in agreement with low-temperature photoluminescence. This work constitutes a promising approach for integrating telecommunications-wavelength quantum dot lasers and entangled photon emitters on the Si integrated photonics platform.

MnO@Mn2O3 nanocrystals embedded in biochar networks for sustainable anode of lithium-ion batteries

MnO is an alternative for commercial graphite as anode material for lithium-ion batteries (LIBs), if the issue of unstable performance caused by volume changes, poor conductivity, and changes in valence state of Mn is addressed. In this study, a series of nano MnO/biochar-containing composite materials were prepared with Mn(NO3)2, urea and pomelo peel as raw materials, via simple hydrothermal treatment and calcination, as anode materials for LIBs, where the biochar was used as inexpensive conductive medium and volume buffer. The electrochemical performance of the composite materials shows complicated correlation with the biochar contents, which associate with different carbonization temperatures. Elaborate characterizations with XRD, SEM, TEM, and Mn 2p, Mn 3s XPS spectra were conducted and jointly analyzed, which revealed that the surface of MnO nanocrystals undergoes different degrees of oxidation. The thickness of the surface amorphous Mn2O3 layer on the MnO nanocrystals influences the long-term electrochemical stability more significantly than the circumstances of biochar encapsulation, which was proved through cyclic voltammetry (CV) measurements. A composite material with moderate biochar content and thin layer of Mn2O3 coating on MnO nanocrystals will show more stable electrochemical performance. Based on this principle, one regulated composite material (MnOx/BC-650) gives an ultra-stable capacity of 446.9 mAh∙g−1 at 500 mA∙g−1 after 200 cycles. This study provides new insight for both revealing the true structure of manganese oxides and developing long-term stable MnO-containing anode materials for LIBs.

Analysis of the Structure of Heavy Ion Irradiated LaFeO3 Using Grazing Angle X-ray Absorption Spectroscopy.

Crystalline ceramics are candidate materials for the immobilization of radionuclides, particularly transuranics (such as U, Pu, and Am), arising from the nuclear fuel cycle. Due to the α-decay of transuranics and the associated recoil of the parent nucleus, crystalline materials may eventually be rendered amorphous through changes to the crystal lattice caused by these recoil events. Previous work has shown irradiation of titanate-based ceramics to change the local cation environment significantly, particularly in the case of Ti which was shown to change from 6- to 5-fold coordination. Here, this work expands the Ti-based study to investigate the behavior in Fe-based materials, using LaFeO3 as an example material. Irradiation was simulated by heavy ion implantation of the bulk LaFeO3 ceramic, with the resulting amorphous layer characterized with grazing angle X-ray absorption spectroscopy (GA-XAS). Insights into the Fe speciation changes exhibited by the amorphized surface layer were provided through quantitative analysis, including pre-edge analysis, and modeling of the extended X-ray absorption fine structure (EXAFS), of the GA-XAS data.

Dynamics of phase transformations in Si and Ge upon strong excitation with UV femtosecond laser pulses

Femtosecond laser processing of semiconductors has evolved into a mature, high-precision fabrication technique, enabling a wide range of applications. While initially most studies have employed pulses at near infrared wavelengths, the interest in using UV laser pulses is constantly increasing due to the different excitation conditions as a consequence of the much shorter optical penetration depth, leading to an improved resolution. In this context, fundamental studies on the temporal dynamics of phase transformations triggered by such pulses are necessary in order to comprehend and eventually control the complex phase transformation pathways. Here, we report a detailed time-resolved study on the phase transformation dynamics of crystalline silicon and germanium upon irradiation with single 400 nm, 100 fs laser pulses in the moderate and high excitation regime. To this end, we have employed fs-resolved optical microscopy with a probe wavelength of 800 nm to study the reflectivity evolution of the irradiated surface over a temporal window ranging from 100 fs up to 20 ns. At moderate excitation fluence, the data reveals the entire sequence of laser-induced processes, starting from the generation of a free-electron plasma, non-thermal melting, ablation onset and expansion of a semi-transparent ablation layer with sharp interfaces. At excitation with peak fluences more than 30 times the ablation threshold, an anomalous transient high-reflectivity state is observed, which might be indicative of a recoil pressure-induced liquid–liquid phase transition. Moreover, 70 nm-thick amorphous surface layers are formed in both materials after irradiation at moderate fluences. Overall, our results provide relevant information on both, transformation dynamics and final state of both materials for fs-pulse excitation in the near-UV wavelength range.

Zero Voltage-Degradation of Li2MnO3 with Ultrathin Amorphous Li─Mn─O Coating.

Manganese-based lithium-rich layered oxides (Mn-LLOs) are promising candidate cathode materials for lithium-ion batteries, however, the severe voltage decay during cycling is the most concern for their practical applications. Herein, an Mn-based composite nanostructure constructed Li2MnO3 (LMO@Li2MnO3) is developed via an ultrathin amorphous functional oxide LixMnOy coating at the grain surface. Due to the thin and universal LMO amorphous surface layer etched from the lithiation process by the high-concentration alkaline solution, the structural and interfacial stability of Li2MnO3 are enhanced apparently, showing the significantly improved voltage maintenance, cycle stability, and energy density. In particular, the LMO@Li2MnO3 cathode exhibits zero voltage decay over 200 cycles. Combining with ex situ spectroscopic and microscopic techniques, the Mn2+/4+ coexisted behavior of the amorphous LMO is revealed, which enables the stable electrochemistry of Li2MnO3. This work provides new possible routes for suppressing the voltage decay of Mn-LLOs by modifying with the composite functional unit construction.

Boosting photocatalytic performance in Cu doped ZnO nanocomposites: Investigation of exciton-free carrier conversion and oxygen vacancy dynamics

The production of photocatalytic materials with strong light absorption ability and high quantum efficiency by simple means is a long-term goal of photocatalytic technology. In this work, we have synthesized Cu doped ZnO nanoparticles by a facile sol-gel method. By introducing Cu impurities, it is shown that the excitons in ZnO have been efficiently separated into free carriers, leading to optimized photocatalytic performance. The surface amorphous layers of the nanoparticles grew thicker at the introduction of Cu atoms into ZnO lattice, which boosted the photocatalytic ability due to the increase of surface oxygen vacancy concentration. This finding provides a direct evidence of quasi-particle-free carrier conversion in Cu doped ZnO, as well as a guidance for fabricating high efficiency ZnO based nano-photocatalysts.

Dependence of the M choice on the properties of Hf(M)SiCN (M = Nb, Ta, Ti, Zr) ceramic coatings: ab-initio and experimental study

The HfMSiCN coatings (M = Nb, Ta, Ti, Zr) are researched using ab-initio theoretical method and double glow plasma surface alloying. The aim is to enhance the high temperature stability and wear resistance of these coatings, alongside optimizing mechanical and thermodynamic properties. Firstly, the calculated mechanical properties for Hf0.5M0.5CN correlate with those experimental measurement for HfMSiCN. Secondly, the thermodynamic parameters exhibit that the Hf0.5Zr0.5CN has the lowest thermal expansion coefficient and higher bulk modulus at high-temperatures. Moreover, the wear rate of HfZrSiCN at 500 ℃ is less than 60% of its wear rate at 300 ℃. The superior wear resistance of HfZrSiCN coating is attributed to a friction-induced composite layer including a dense amorphous nanocomposite surface layer and a nano-friction glaze layer supported by nanograins.

LDH nanocrystal@amorphousness core–shell structure derived from LDH → LDO transformation: Synergistically enhanced energy stored for LIBs anode

With the emergence of advanced electronics and appliances, there is a growing demand for high power/energy density and cyclic stability of Li-ion batteries (LIBs), which stimulates the development of high-performance electrode materials. Herein, we proposed and implemented a novel strategy of employing the LDH → LDO intermediate-transformation amorphization to improve the performance of LDH as LIBs anode. In this work, flower-like NiCo-LDH nanoparticles (LDHRT) are synthesized for the first time by co-precipitation using triethanolamine (TEA) as an alkali source and H2O2 as a size-controlling reagent. Then, the unique LDH nanocrystal@amorphousness core–shell structure was obtained by fine-tuning the heat treatment, which significantly improved the electrochemical properties of the material. The layered structure of LDH and the internal defects of the amorphous phase provide abundant transport channels and a larger accommodation space for Li+, improving the rate capability and capacity of LIBs. In addition, the surface amorphous layer and the reduced size of LDHRT nanocrystals effectively alleviate the volume effect, improving the cycling stability of the electrode material. As a result, superior capacity (1821.3 mAh g−1 at 0.1 A g−1), rate capability, and cyclic stability (∼687.7 mAh g−1 at 0.5 A g−1 after 500 cycles, with the average capacity attrition rate of 0.092 %) were achieved. The Li+ diffusion coefficient and capacity retention rate (after 300 cycles) are higher than nearly 3 orders of magnitude and 50.12 % compared to the LDHRT, respectively. This study has opened a simple, safe, and economical new avenue for developing high-performance electrode materials.

Surface Reconstruction on Metal Nitride during Photo-oxidation.

The efficient conversion and storage of solar energy for chemical fuel production presents a challenge in sustainable energy technologies. Metal nitrides (MNs) possess unique structures that make them multi-functional catalysts for water splitting. However, the thermodynamic instability of MNs often results in the formation of surface oxide layers and ambiguous reaction mechanisms. Herein, we present on the photo-induced reconstruction of a Mo-rich@Co-rich bi-layer on ternary cobalt-molybdenum nitride (Co3 Mo3 N) surfaces, resulting in improved effectiveness for solar water splitting. During a photo-oxidation process, the uniform initial surface oxide layer is reconstructed into an amorphous Co-rich oxide surface layer and a subsurface Mo-N layer. The Co-rich outer layer provides active sites for photocatalytic oxygen evolution reaction (POER), while the Mo-rich sublayer promotes charge transfer and enhances the oxidation resistance of Co3 Mo3 N. Additionally, the surface reconstruction yields a shortened Co-Mo bond length, weakening the adsorption of hydrogen and resulting in improved performance for both photocatalytic hydrogen evolution reaction (PHER) and POER. This work provides insight into the surface structure-to-activity relationships of MNs in solar energy conversion, and is expected to have significant implications for the design of metal nitride-based catalysts in sustainable energy technologies.

The hydrogen activation, migration, and hydrogenation on metal-free TiH2(O)

Hydrogen activation and migration of active hydrogen species are of great significance for the hydrogen-involving reaction and have attracted much attention. Herein, we reported an unexpected result that H2 activation occurred on a TiH2(O) material, which possesses a unique structure with TiH2 in the core and an amorphous TiOxHy surface layer. The TiOxHy surface layer enriched with defects and “TiOO” species account for the intrinsic activity of TiH2(O) for H2 heterolytic cleavage. As a hydrogen-rich material, TiH2(O) acts as a hydrogen reservoir, favoring not only the spillover of active hydrogen species on the surface layer but also their migration into the bulk phase of TiH2. Without the addition of extra active metals, TiH2(O) exhibited excellent catalytic performance in the hydrogenation of biomass-derived vanillin.

Fluorine-doped CoP/Ni2P nanowires for enhanced hydrogen evolution activity

Doping hetero-atoms into non-noble metal phosphides is an important strategy for enhancement of hydrogen evolution reaction (HER) performance. Herein, we prepare a self-supported F-doped CoP/Ni2P nanowire arrays grown on Ni foam by using a strategy with three steps including hydrothermal reaction, fluorination, and low-temperature phosphorization. The F-CoP/Ni2P nanowire consists of a well-defined crystalline core and a thin amorphous surface layer. The F-doping and amorphous surface layers effectively expose a large number of active sites, optimize the electronic configuration of Ni, Co and P on the surface, and promote the electron transport performance. As a result, the prepared F-CoP/Ni2P@NF-II exhibits excellent electrocatalytic activity for HER in alkaline electrolyte with a lower overpotential of 75 mV at 10 mA cm−2, a small Tafel slope of 54.8 mV dec−1, and good durability. This work provides a simple method for developing transition metal phosphate-based catalysts towards hydrogen evolution reaction.

Greatly Boosting Seawater Hydrogen Evolution by Surface Amorphization and Morphology Engineering on MoO2/Ni3(PO4)2

AbstractHydrogen production through seawater electrolysis faces several challenges, one of which involves the development of electrocatalysts with high catalytic performance. Here, surface amorphization and morphology engineering are combined to design a novel electrocatalyst for highly‐efficient hydrogen evolution reaction (HER). The surface‐amorphized MoO2/Ni3(PO4)2 microcolumns supported on nickel foam (SA‐MoO2/Ni3(PO4)2/NF) display remarkable performance with low overpotentials of 34 and 46 mV at a current density of 10 mA cm−2 in 1 m KOH and alkaline seawater, respectively. In addition, the alkaline electrolysis cell (AEC) integrated with SA‐MoO2/Ni3(PO4)2/NF as the cathode and Ni foam as the anode achieves a current density of 100 mA cm−2 at 1.87 V in 6 m KOH seawater at 60 °C, superior to that of industrial NiMo electrode as cathode (2.05 V). DFT calculations demonstrate that the surface amorphous layer (MoOx) improves the hydrogen adsorption energy of sample and reduces the energy barrier of water dissociation. It is found that substantial improvement in catalytic performance stems from the synergistic effect between surface amorphization and unique microcolumn morphology. These findings may provide insights into combining surface amorphization and morphology engineering strategies to enhance catalytic performance and pave the way for the development of highly efficient seawater HER electrocatalysts.

Anodic/Cathodic Properties of Ni Based Catalysts for Anion Electrolyte Membrane Water Electrolysis

Anion electrolyte membrane water electrolysis (AEM WE) using non-precious metal catalyst is one of the most prospective systems for pure hydrogen generation. The Ni based oxide shows relatively lower overpotential of oxygen evolution reaction (OER) by adding the transition metals of Co, Fe and Mn, and approaches that of precious metal of Ir based oxide. Our previous study reported that the Ni-Co based catalyst was highest OER activity at operating temperature. The crystallized Ni-Co metal-based core particles with amorphous Ni oxyhydrates of top surface (shell) was confirmed to be preferable to obtain the higher OER activity by rotating disk electrode method, transmission electron microscopy and DFT calculation. Moreover, the fused aggregated network microstructure of Ni-Co based catalyst assisted to show a metallically electronic conductivity. In this study, we evaluated both OER and hydrogen evolution reaction (HER) activity of Ni based catalysts to confirm the prospective non-precious metal catalysts for AEM WE.Each Ni based catalysts with additive of transition metals were synthesized by the flame oxide-synthesis method.1 The OER and HER activities of these catalysts were evaluated in 1 M KOH at 20 to 80 oC by use of the RDE. The Ni-Co based catalyst was highest OER activity in these Ni based catalysts obtained above. The amorphous top surface layer was correlated with a negative shift in the oxyhydroxide formation peak potential from the results of DFT calculations. 2 The HER activity of the Ni-Fe based catalyst also showed the higher OER activity. Especially, the Ni-Fe based catalyst had highest HER activity in these Ni cased catalysts above. The HER activity enhanced by the construction of well crystallized top surface in comparison with its amorphous or poorly crystalline ones. DFT calculation indicated that the defective or disordered surface was not as active for the HER. These results will provide a strategy of Ni based catalysts optimization for AEM. Acknowledgement This work was partially supported by funds for the JSPS KAKENHI (20H02839), and the project from the New Energy and Industrial Technology Development Organization (NEDO) of Japan. References Kakinuma, M. Uchida, T. Kamino, H. Uchida, and M. Watanabe, Electrochim. Acta, 56, 2881 (2011).Shi, T. Tano, D. A. Tryk, A. Iiyama, M. Uchida, and K. Kakinuma, ACS Catal., 11, 5222 (2021). Figure 1

High-Performance Solar-Blind Ultraviolet Photodetectors Based on β-Ga2O3 Thin Films Grown on p-Si(111) Substrates with Improved Material Quality via an AlN Buffer Layer Introduced by Metal-Organic Chemical Vapor Deposition.

We have achieved significantly improved device performance in solar-blind deep-ultraviolet photodetectors fabricated from β-Ga2O3 thin films grown via metal-organic chemical vapor deposition (MOCVD) on p-Si(111) substrates by improving material quality through the use of an AlN buffer layer. High-structural-quality β-Ga2O3 films with a (-201) preferred orientation are obtained after the introduction of the AlN buffer. Under 3 V bias, the dark current reaches a minimum of 45 fA, and the photo-to-dark current ratio (PDCR) reaches 8.5 × 105 in the photodetector with the metal-semiconductor-metal (MSM) structure. The peak responsivity and detectivity are 38.8 A/W and 2.27 × 1015 cm·Hz1/2/W, respectively, which are 16.5 and 230 times that without the buffer layer. Additionally, benefiting from the introduction of the AlN layer, the photodetection performance of the β-Ga2O3/AlN/Si heterojunction is significantly improved. The PDCR, peak responsivity, and detectivity for the β-Ga2O3/AlN/p-Si photodetector at 5 V bias are 2.7 × 103, 11.84 A/W, and 8.31 × 1013 cm·Hz1/2/W, respectively. The improved structural quality of β-Ga2O3 is mainly attributed to the decreased in-plane lattice mismatch of 2.3% for β-Ga2O3(-201)/AlN(002) compared to that of 20.83% for β-Ga2O3(-201)/Si(111), as well as the elimination of the native amorphous SiOx surface layer on the Si substrate during the initial growth of oxide thin films.

High-quality TEM specimen preparation for lithium-ion conducting solid electrolytes by low-energy ion milling

Focused ion beam (FIB) is a widely used method to prepare transmission electron microscopy (TEM) specimen from bulk materials. However, the surface amorphous layer induced by ion beam is an obstacle to obtain high-quality atomic-scale images for quantitative analysis, especially for the analysis of light elements such as lithium in lithium-ion conducting solid electrolytes. Here, taking lithium-ion conducting solid electrolyte materials as an example, the advantages and disadvantages of applying low-energy Ar+ ion for fine milling after FIB are investigated. Combining Monte-Carlo simulations with ion milling experiments, the milling parameters are evaluated and discussed in detail. With optimized parameters, TEM specimens with less beam damage and thinner amorphous layer were prepared, enabling the acquisition of high-quality atomic-scale images. Furthermore, low-energy Ar+ ion milling is also able to remove hydrocarbon contamination formed during the electron beam illumination inside the microscope, making the contaminated TEM specimens reusable.

Turning on Lithium-Sulfur Full Batteries at -10 °C.

Lithium-sulfur (Li-S) batteries using Li2S and Li-free anodes have emerged as a potential high-energy and safe battery technology. Although the operation of Li-S full batteries based on Li2S has been demonstrated at room temperature, their effective use at a subzero temperature has not been realized due to the low electrochemical utilization of Li2S. Here, ammonium nitrate (NH4NO3) is introduced as a functional additive that allows Li-S full batteries to operate at -10 °C. The polar N-H bonds in the additive alter the activation pathway of Li2S by inducing the dissolution of the Li2S surface. Then, Li2S with an amorphized surface layer undergoes the modified activation process, which consists of the disproportionation and direct conversion reaction, through which Li2S is efficiently converted into S8. The Li-S full battery using NH4NO3 delivers a reversible capacity and cycling stability over 400 cycles at -10 °C.