Simple Ball Milling Process Research Articles

Ball-Milled P-CuGaO2 Particles As a Semitransparent Scaffolding Material for Dye-Sensitized Molecular Photocathodes

Dye-sensitized photocathodes using a metal complex as a photosensitizer are attractive candidates for catalytic material conversion reactions such as H2 evolution and CO2 reduction (Figure A). Band position, conductivity, and morphology of the p-type semiconductor scaffold electrode significantly affect the electron injection into the metal complex and the subsequent reaction process. Consequently, the properties of the semiconductor material can be one of the important factors the catalytic activity of the photocathodes.We have previously reported p-type semiconductor CuGaO2 for the scaffold materials that exhibits a higher photocurrent and a positive onset potential compared to the conventionally used NiO, when combined with a Ru-tris-bipyridine-type photosensitizer[1]. Owing to the thermophysical property of CuGaO2, the typical solid-state synthesis of CuGaO2 particles needs high-temperature calcination with around 1373 K under an inert atmosphere, resulting in the large particle size of several microns and the limited conductivity and small surface area. Therefore, the photocathode activity is still insufficient. Other processes such as solvothermal synthesis have been reported, but it is still difficult to control the particle size, shape and chemical state.In this study, we examined the ball milling to synthesize nano-sized fine CuGaO2 particles and to prepare a semitransparent scaffold electrode for dye-sensitized photoelectrochemical reaction. Planetary ball milling has been reported as the means to obtain fine semiconductor particles[2], while it is necessary to adjust the processing conditions and perform detailed analysis because there is a possibility of damaging the semiconductor and impairing its physical properties.The XRD pattern, UV-visible absorption spectrum, XPS, and XAFS measurements of the ball-milled CuGaO2 particles revealed that there was no obvious deterioration due to the treatment.The SEM image of the ball-milled CuGaO2 electrode implied that the particles, which have been miniaturized about less than several hundred nm by the treatment, formed a dense layer, showing the semi-transparency of the electrode (Figure B). Detailed observation also proved that the ball-milled particles keep the crystal habit. The photocathode with ball-milled CuGaO2 modified with Ru-tris-bipyridine-type complex exhibited a reduction current by photoexcitation of the photosensitizer, and the current value exceeded those of the photocathodes using an untreated CuGaO2 electrode and a NiO electrode under the same conditions. The results suggest that the the miniaturization improved the characteristics of the photocathodes. The current study showed a way to mass-produce high-performance semiconductor scaffold electrodes by a simple ball-milling process.[1] H. Kumagai, O. Ishitani, et al., Chem. Sci. 2017, 8, 4242.; C. Windle, H. Kumagai, R. Abe, O. Ishitani, V. Artero, et al., J. Am. Chem. Soc., 2019, 141, 9593. [2] K. Okuno, H. Kumagai, H. Kato, et al., Sustain. Energy Fuels, 2022,6, 1698. Figure 1

PV Silicon Recovery for Lithium Ion Battery Anodes

As solar photovoltaic (PV) devices across the globe reach the end of their approximately 30-year lifetimes, an emerging challenge is how to handle the waste from large volumes of end-of-life (EOL) PV modules. It is projected that the cumulative mass of EOL PV modules could be up to 8 million tonnes (Mt) by 2030 so recovery of high value materials from these EOL modules through a cost efficient recycling process would minimize environmental impacts compared to disposing them in landfills[1]. A typical recycling process for EOL PV modules involves mechanical disassembly, separation of the tempered cover glass and silicon wafer followed by purification and recovery of other constituents such as Pb or Ag with the goal of reinstating the recovered materials as a PV module. However, since new module prices continue to decline and the recovered PV modules typically have a shorter lifetime and lower efficiency, the economic value of using the recovered PV materials to manufacture a new PV module is uncertain[2]. Since silicon, particularly boron-doped, is a promising candidate for next-generation anodes for lithium-ion batteries (LIB), recovering the silicon from PV modules for use in LIB anodes could be an attractive alternative. In this study we leverage the National Renewable Energy Laboratory (NREL)’s expertise in PV Si reliability and access to multiple types of EOL PV modules to study the merits of B-doped silicon recovery from silicon PV panels with regard to silicon anode cycling performance and calendar life. A simple ball milling process was developed to prepare recycled Si from EOL PV modules for use as in a LIB anode. In this talk we will be discussing the recovery efficiency, purification requirements and key anode performance metrics of recycled PV silicon materials. IRENA, I.-P., End-of-Life Management: Solar Photovoltaic Panels 2016: International Renewable Energy Agency and International Energy Agency Photovoltaic Power Systems.A. Wade, P.S., K. Drozdiak, E. Brutsch. Beyond Waste – The Fate of End-of-Life Photovoltaic Panels from Large Scale PV Installations in the EU. The Socio-Economic Benefits of High Value Recycling Compared to Re-Use. in 33rd European Photovoltaic Solar Energy Conference and Exhibition. 2017.

Effect of Water-Soluble CMC/SBR Binder Ratios on Si-rGO Composites Using µm- and nm-Sized Silicon as Anode Materials for Lithium-Ion Batteries

Silicon-containing materials are still the most promising alternatives to graphite as the negative electrodes of lithium-ion batteries. However, the different Li+ storage mechanism combined with the high capacity result in new requirements for the passive electrode components, such as the binder. To ensure sufficient cycling stability, silicon must be embedded in a suitable carbonaceous matrix. For this purpose, we used a simple ball milling process with reduced graphene oxide (rGO) to produce Si-rGO composites with µm- and nm-sized silicon particles. The rGO was synthesized previously from a two-step thermal synthesis method developed in-house. Subsequently, electrodes with varying CMC/SBR ratios (3:1, 1:1, and 1:3) were prepared from the composites containing the different Si particle sizes. It was found that the optimal binder ratio depends on the size of the Si particles. For the nm-Si-rGO composite, a CMC/SBR ratio of 3:1 results in a total capacity over 51 cycles of 20.6 Ah g−1, which means an improvement of 20% compared to CMC/SBR = 1:3 (17.1 Ah g−1). In contrast, we demonstrate that for µm-Si-rGO composites with an optimal CMC/SBR ratio of 1:1 (13.0 Ah g−1), compared to nm-Si-rGO, a higher SBR content is beneficial for the cycling behavior. Moreover, a comparison with graphite from the literature indicates that a rGO-matrix reduces the need for SBR.

Facile fabrication of Li5Cr7Ti6O25@Li0.33La0.56TiO3 composites as promising anode materials for high-performance Li-ion batteries

Li5Cr7Ti6O25 has been considerd as a hopeful anode material of Li-ion batteries due to the low cost. Nonetheless, the intrinsically low conductivity obviously reduces reversible capacity and cycle performance. In this work, we design Li5Cr7Ti6O25@Li0.33La0.56TiO3 (LCTO@LLTO) composites by simple ball-milling process followed by a post-calcination at air atmosphere, which realizes an excellent cycle performance. The Li0.33La0.56TiO3 (LLTO) coating does not alter the morphology and particle size of the Li5Cr7Ti6O25 (LCTO) material, but increses the lattice parameter. The right level LLTO modification can improve the transfer ability of ions and electrons with enhanced lithiation/delithiation dynamics, making a good cycling stability and rate capability of as-prepared LCTO anode. As a result, LCTO@LLTO(5 wt%) shows a high charge capacity of 149.8 mAh g−1 even at 1C in the 50th cycle, much higher than that LCTO with a capacity of 126.3 mAh g−1. The improved electrochemical performance of LCTO@LLTO composites can be attribute to the enhanced Li ion diffusion kinetics, electrochemical reversibility and ion conductivity by LLTO modification. Therefore, the LLTO modificationcan be regarded as an efficient way for construct the anode materials for high-perfprmance Li-ion batteries.

Ball-milled Ni2P/g-C3N4 for improved photocatalytic hydrogen production

Transition metal phosphides (TMPs) are ideal candidates to replace precious cocatalysts for photocatalytic hydrogen evolution reaction (HER). Understanding the structure-activity relationships between TMPs and the host photocatalysts is an important criterion for the development of highly active TMPs for HER. In this work, the relations were explored with Ni2P and g-C3N4 as prototypes. Ni2P with a clear composition and structure was prepared first by a mild solvothermal method and was then loaded on g-C3N4 with an exact content through a ball milling process. The effects of the modification of Ni2P on g-C3N4 structure, absorption, texture, HER activity, and photo-electrochemical properties were investigated. The results demonstrated that the crystal structure and the texture of g-C3N4 are less impacted by the decoration of Ni2P, but the HER activity can be substantially improved. g-C3N4 modified with 3% Ni2P showed the highest HER performance and it is ca. 9 times higher than the pristine g-C3N4 even Ni2P was loaded just by a simple ball milling process. Ni2P played a dual role as trapping sites to capture photoinduced electrons and the reactive centers to trigger the evolution of hydrogen for its high work function and the low HER overpotential. This work reveals some reliable structure-activity relationships between Ni2P and g-C3N4 and offers a simple approach to synthesize highly efficient Ni2P and its loading on host photocatalyst for enhanced HER.

Sustainable Low-Temperature Coating of LATP/C Solid Electrolyte Composites on LiNi1/3Co1/3Mn1/3O2 Cathode Based on Lithium Iodide Solvent-Recrystallization for Li-Ion Batteries

A mixed ionic (Li1.3Al0.3Ti1.7(PO4)3: LATP) and electronic conductor (porous carbon: C) hybrid layer can effectively enhance the electrochemical performance of cathode materials. In this work, a sustainable low-temperature synthesis strategy (≤200 °C) combining ball milling and solvent-recrystallization of lithium iodide is first proposed to prepare the LATP/C coated LiNi1/3Co1/3Mn1/3O2 (LNCMO) material. The characterizations of structures and morphology reveal that LATP and porous carbon powder are mixed into the ethanol dissolved lithium iodide by a simple ball milling process, then the lithium iodide is recrystallized to serve as a binder when ethanol is vaporized at a low temperature to coat uniform thickness and homogeneously distributed LATP/C on the surface of LNCMO cathode. The charge-discharge results illustrate that the cycling performance and rate discharge capability of the active materials coated with LATP/C are significantly superior to the bare LNCMO. AC impedance analysis confirms that lower charge transfer resistance and higher Li+ ion diffusion coefficient are achieved in cathode materials. This work successfully exploited a novel low-temperature cathode coating method based on lithium iodide solvent-recrystallization and obtained results comparable to high-temperature processes without suffering from side reaction problems.

(Invited) Wastewater Derived Cathode Materials for Aqueous Zn-Batteries

While lithium-ion batteries (LIBs) have been widely used for portable devices and electric vehicles, it is highly desirable to develop safer and less expensive batteries as alternative to LIBs. In this regard, zinc (Zn) batteries have attracted much attention because of their excellent safety and low cost. However, one of the challenges is to develop cost-effective and highly efficient cathode materials for Zn-ion batteries (ZIBs) based on transition metal oxides. It would be more economical to recycle transition metals in order to reduce the fabrication cost. Co-precipitation method is widely used for synthesis of LIBs cathode materials, and large amount of wastewater would be produced during co-precipitation and battery production process. In this presentation, we will report a facile and general process for fabrication of cathode materials for aqueous Zn-ion batteries (ZIBs) by reusing wastewater from co-precipitation method. We have selected manganese rich phases with different ratio of nickel to cobalt precursors from co-precipitation wastewater, followed by a simple ball milling process, resulting in metal-hydroxide cathode materials (Mn0.6Ni0.1Co0.3OxHy, Mn0.6Ni0.2Co0.2OxHy, and Mn0.6Ni0.3Co0.1OxHy). Among them, the Mn0.6Ni0.1Co0.3OxHy cathode (with mass loading of 15 mg cm-2) exhibits an initial capacity of 263 mAh g-1 at a current density of 0.1 A g-1, as evaluated in an mixture electrolyte (2M ZnSO4 and 0.1M MnSO4). Furthermore, operando X-ray absorption spectroscopy analysis has revealed the role of each transition metal ions during insertion and desertion of Zn ions. It is found that the ratio of Ni to Co significantly influences ZIBs performances, providing important insight into rational design of more efficient cathode materials for aqueous Zn-ion batteries. Figure 1

Enteromorpha prolifera biochar as a novel ball milling aid for enhancing the interfacial reaction activity of microscale zero-valent iron (mZVI) for Cr(VI) removal from water

Ball milling (BM) is a promising approach to activate microscale zero-valent iron (mZVI), in which the grinding aids are essential. Yet, previous researches have shown that carbon could act as a grinding aid while the grinding mechanism of carbon is seldom revealed. In this study, Enteromorpha prolifera biochar (EBC), from the pyrolysis of large harmful algae, was selected as a novel grinding aid to prepare a carbon-modified mZVI composite (EBC-mZVIbm) to enhance the activity of mZVI in water. After a simple BM process with the help of carbon, the previously inert mZVI exhibited excellent reductive performance. EBC outperformed other carbons as grinding aid for Cr(VI) removal over a wide pH range (3.00–11.00), and EBC dosage and rotation speed were the critical factors for the mZVI activating in the BM process. The grinding mechanism of EBC was demonstrated. EBC could diffuse to the mZVI surface under mechanical collision and serve as a surface coating to inhibit the agglomeration of mZVI. The presence of EBC enhanced the electrical conductivity and adsorption ability by changing the specific surface area, the oxygen-containing functional groups and defective structures, which facilitated the interfacial reaction between mZVI and Cr(VI). Cr(VI) was removed by a chemisorption-reduction process and Fe(II) played a key role. There were no chromium and iron ions in the solution after reaction. This study provided a new strategy for efficiently activating mZVI with a dry one-pot procedure, a new understanding of carbon grinding mechanism and a new material for heavy metal ions recovery.

Interface Modification and Halide Substitution To Achieve High Ionic Conductivity in LiBH4-Based Electrolytes for all-Solid-State Batteries

A fast solid-state Li-ion conductor Li16(BH4)13I3@g-C3N4 was synthesized using a simple ball-milling process. Because of the combined effect of halide substitution and the formation of an interface between Li16(BH4)13I3 and g-C3N4, Li16(BH4)13I3@g-C3N4 delivers a high ionic conductivity of 3.15 × 10-4 S/cm at 30 °C, which is about 1-2 orders of magnitude higher than that of Li16(BH4)13I3. Additionally, Li16(BH4)13I3@g-C3N4 exhibits good electrochemical stability at a wide potential window of 0-5.0 V (vs Li/Li+) and excellent thermal stability. The Li/Li symmetrical cell based on the Li16(BH4)13I3@g-C3N4 electrolyte achieves long-term cycling with a small increase in overpotential, confirming superior electrochemical stability against Li foil. More importantly, Li16(BH4)13I3@g-C3N4-based Li batteries are compatible with S-C and FeF3 cathodes and MgH2 anodes and can achieve long-term cycling with Li4Ti5O12 anodes at a temperature range from 30 to 60 °C. The developed strategy of coupling halide substitution together with interface modifications may open a new avenue toward the development of LiBH4-based high ionic conductivity electrolytes for room-temperature all-solid-state Li batteries.

Scalable synthesis of silicon nanoplate-decorated graphite for advanced lithium-ion battery anodes.

A silicon nanoplate-decorated graphite design is developed for lithium battery anodes via a simple ball milling process. The resultant silicon-graphite electrodes show high cycling stability with high capacity, superior rate capability, and excellent electrode stability when compared to their counterparts, attributable to two-dimensional silicon and its area-to-area contact with graphite.

Petroleum waste hydrocarbon resin as a carbon source modified on a Si composite as a superior anode material in lithium ion batteries

We demonstrate impressive electrochemical performance of a silicon(Si)/carbon(C) composite prepared by mixing an appropriate concentration of hydrocarbon resin, Si powder, and polyacrylic acid followed by a simple ball milling process and heat treatment at temperatures ranging from 600°C to 900 °C. The Si/C composite annealed at 700 °C achieved a significantly high discharge capacity (2291 mAh g−1) in the first cycle, very good cyclic stability (1402 mAh g−1 after 100 cycles), and excellent rate capability (1020 mAh g−1 at 2C with a retention of 95.5%). The composites annealed at high temperatures (800 °C and 900 °C) also displayed good capacity (1330 mAh g−1, 1340 mAh g−1) after 100 cycles and high rate capability (676 mAh g−1, 619 mAh g−1 @2C). indicating outstanding physical/chemical/structural stability of the composite that makes it a very suitable anode material in lithium ion batteries. The annealing temperature led to the formation of a C, SiOC/SiOx layer over the Si, as observed through a microstructure analysis, and different degrees of oxidation of the Si were observed using X-ray photoelectron spectroscopy. A detailed, comprehensive analysis of the structure/microstructure, bond vibrations, oxidation states of Si, and electrochemical performance is carried out.

In situ sulfur-doped graphene nanofiber network as efficient metal-free electrocatalyst for polysulfides redox reactions in lithium–sulfur batteries

Abstract The major challenge for realistic application of Li-S batteries lies in the great difficulty in breaking through the obstacles of the sluggish kinetics and polysulfides shuttle of the sulfur cathode at high sulfur loading for continuously high sulfur utilization during prolonged charge-discharge cycles. Here we demonstrate that large percentage of sulfur can be effectively incorporated within a three-dimensional (3D) nanofiber network of high quality graphene from chemical vapor deposition (CVD), through a simple ball-milling process. While high quality graphene network provided continuous and durable channels to enable efficient transport of lithium ions and electrons, the in-situ sulfur doping from the alloying effect of ball milling facilitated desirable affinity with entire sulfur species to prevent sulfur loss and highly active sites to propel sulfur redox reactions over cycling. This resulted in remarkable rate-performance and excellent cycling stability, together with large areal capacity at very high sulfur mass loading (Specific capacity over 666 mAh g−1 after 300 cycles at 0.5 C, and areal capacity above 5.2 mAh cm−2 at 0.2 C at sulfur loading of 8.0 mg cm−2 and electrolyte/sulfur (E/S) ratio of 8 µL mg−1; and high reversible areal capacities of 13.1 mAh cm−2 at a sulfur load of 15 mg cm−2 and E/S of 5 µL mg−1).

One-pot resource-efficient synthesis of SnSb powders for composite anodes in sodium-ion batteries.

SnSb alloy, which can be used as an anode in a sodium-ion cell, was synthesized following a resource-efficient route at low temperature. This one-pot approach greatly reduces the energy consumption and maximizes the efficient use of raw materials. The reaction of elemental tin and antimony in the ionic liquid (IL) trihexyltetradecylphosphonium chloride ([P66614]Cl) at 200 °C led to a microcrystalline powder of single-phase SnSb within 10 h with very high yield (95%). Liquid-state nuclear magnetic resonance spectroscopy revealed that the IL remains essentially stable during the reaction. It was recovered almost quantitatively by distilling off the organic solvent used for product separation. Composites of SnSb powder and carbon nanotubes (CNTs) were fabricated by a simple ball milling process. Electrochemical measurements demonstrate that the Na‖SnSb/CNTs cell retains close to 100% of its initial capacity after 50 cycles at a current of 50 mA g−1, which is much better than the Na‖SnSb cell. The greatly increased capacity retainability can be attributed to the conductive network formed by CNTs inside the SnSb/CNTs electrode, providing 3D effective and fast electronic pathways during sodium intercalation and de-intercalation.

Si-based composite interconnected by multiple matrices for high-performance Li-ion battery anodes

To obtain anode materials with high performance Li-ion batteries, a nanostructured Si-based composite, including Si, a Li-inactive conducting Cu3Si matrix, and multiple carbon-based matrices (carbon nanotube, graphite, and a pyrolytic carbon coating) is developed by facile step-by-step combination of solid-state synthetic technologies. First, various SixCuy alloys with different weight compositions are synthesized by a simple ball-milling process. Among the SixCuy alloys, Si80Cu20, which is comprised of Si and Cu3Si, displays the highest electrochemical performance. To further improve the electrochemical performance of Si-Cu3Si, an interconnected composite with 1D-structured CNT and 3D-structured graphite, Si-Cu3Si-CNT/G, is prepared via an additional ball-milling process. The Si-Cu3Si-CNT/G composite is finally coated via the pyrolysis of polyvinyl chloride, thus forming the carbon-coated Si-Cu3Si-CNT/G-C composite. This final product, Si-Cu3Si-CNT/G-C, is comprised of well-dispersed nanocrystalline Si and Cu3Si (Li-inactive conducting matrix) within the multiple interconnected carbon matrices. The Si-Cu3Si-CNT/G-C displays excellent electrochemical performance, with a high first reversible capacity of 1237 mA h g−1, a high initial coulombic efficiency of 82.8%, a long cycle durability of 1084 mAh g−1 over 100 cycles, and a high rate capability of ~1000 mAh g−1 at 1C-rate, which confirms its commercial application as a high-performance Si-based anode for Li-ion batteries.

Mg@C60 nano-lamellae and its 12.50 wt% hydrogen storage capacity

The design and synthesis of new hydrogen storage materials with high capacity are the prerequisite for extensive hydrogen energy application which can be achieved by multi-site hydrogen storage. Herein, a Mg@C60 nano-lamellae structure with multiple hydrogen storage sites has been prepared through a simple ball-milling process in which Mg nanoparticles (∼5 nm) are homogeneously dispersed on C60 nano-lamellae. The as-obtained C60/Mg nano-lamellae displays an excess hydrogen uptake of 12.50 wt% at 45 bar, which is far higher than the theoretical value (7.60 wt%) of metal Mg and the US Department of Energy (DOE) target (5.50 wt%, 2020 year), also the experimental values reported by now. The enhanced hydrogen storage mainly comes from several storage sites: MgH2, Hx–C60 (CH chemical bonding), H2@C60 (the endohedral H2 in C60). Interestingly, the hybridization of Mg and C60 not only facilitate the dissociation of H2 molecules to form CH bonding with C60, but also promote the deformation of C60 and access H2 molecules into the cavity of C60. This work provides new insight into the underlying chemistry behind the high hydrogen storage capacities of a new class of hydrogen storage materials, fullerene/alkaline-earth metals nanocomposites.

Lattice deformation of LiNi0.5Mn1.5O4 spinel cathode for Li-ion batteries by ball milling

Mechanical processes such as ball milling trigger lattice deformations into particles. The electrochemical performances of the electrode materials used for Li-ion batteries depend on Li+ mobility within the crystal structure. Therefore, the preparation of electrode particles that contain no lattice deformations is required. However, electrode particles are subjected to mechanical stresses during manufacturing processes such as grinding, mixing, and coating of powders. In this study, the introduction of lattice strains and defects into the LiNi0.5Mn1.5O4 (LNMO) spinel by a simple ball-milling process is investigated, together with the relationship between lattice deformation and cathode properties. Lattice strain accumulates in the LNMO crystal with increased milling time, but the crystallite size of the distorted particles reduces in order to mitigate this effect. Although mechanical treatment leads to a decrease in the first discharge capacity, there is a recovery in capacity after the second discharge owing to crystal rearrangement that occurs after the initial extraction and insertion of Li+ from the distorted LNMO spinel. Nonetheless, excessive lattice deformation in the LNMO spinel, which contains a three-dimensional diffusion pathway for Li+, disturbs fast migration. The design and quality management of electrode particles throughout the manufacturing process are key factors for improving battery performances.

Microwave Absorption Properties of Fe-Based Amorphous Particles Prepared Using Ball-Milling Method

Fe73.5Si13.5B9Cu1Nb3 amorphous particles of varying size and shape were prepared using a simple ball-milling process. The phase structure and morphology of the particles were determined by x-ray diffraction and scanning electron microscopy, respectively. The static magnetization and electromagnetic properties of the particles were also measured. Particles that were processed by ball-milling for 35 h possessed excellent microwave-absorbing properties which present not only the widest frequency band of reflection loss (RL) at below − 20 dB over the range 10.8–12.8 GHz but also the maximum absorption peak, − 27.3 dB at a frequency of 11.6 GHz. Higher permeability and lower permittivity were obtained due to decreased particle size and formation of nanocrystalline α-Fe(Si) grains in the amorphous matrix. Particles milled for 15 h and 25 h also exhibited improved electromagnetic wave absorbing performance, with RL values of − 24.9 dB at 9.4 GHz and − 23.4 dB at 9.2 GHz, respectively, owing to the appearance of flake-shaped particles. Thus, Fe73.5Si13.5B9Cu1Nb3 particles processed using a ball-milling process proved to be effective microwave absorbers.

Comparative study of edge-functionalized graphene nanoplatelets as metal-free counter electrodes for highly efficient dye-sensitized solar cells

Edge-functionalized graphene nanoplatelets (GnPs) were synthesized by a simple ball-milling process of graphite in the presence of halogen (F, I), metalloids (Se, Te and Sb) and subsequently applied to dye-sensitized solar cells (DSSCs) as counter electrodes (CEs). In our previous works, a series of edge-functionalized GnPs were thoroughly studied and successfully utilized as CEs in DSSCs, with the aim of finding possible alternatives to the noble and expensive Pt metal as CE. However, in each study, the GnP-CEs were not only fabricated with different dyes and electrolytes but were also evaluated on different occasions, and thus, it was difficult to identify which type of edge-functionalized GnPs was the best. Herein, DSSCs with different edge-functionalized GnP-CEs were fabricated under the same environmental conditions, photovoltaic performances were then evaluated employing both I−/I3− and Co(bpy)32+/3+ (bpy = 2,2′-bipyridine) redox couples with three different sensitizers to assess the electrocatalytic activity of the different GnP-CEs. Photovoltaic performances of edge-halogenated GnP-CEs with N719 dye employing the I−/I3− redox couple were lower than those of the metalloid-doped GnP-CEs and were even inferior to Pt-CE, which was consistent with the Rct values. Conversely, among the metalloid-doped GnP-CEs, SbGnP-CE exhibited a higher Rct value and lower power conversion efficiency (PCE) value of 8.70% and 6.60% with N719 and SGT-130 dyes, respectively. However, when the devices were fabricated with the Co(bpy)32+/3+ redox couple, the opposite occurred and SbGnPs displayed the highest PCE of 10.42% with SGT-130 dye and 12.08% with SGT-021 dye. Furthermore, SeGnP-CE and TeGnP-CE showed superior compared to the Pt-CE with both I−/I3− and Co(bpy)32+/3+ electrolyte solutions.

Chemically C-B bonded C60/CoB composite and its enhanced electrochemical hydrogen storage property

In this work, amorphous CoB has been uniformly coated on C60 surfaces through a simple ball milling process. Accordingly their XRD, SEM and TEM measurements clarify their related composite structures. Especially, a C-B chemical bond has been found through its XPS measurement, which enhanced the composite's stability and electrochemical activity. And the following electrochemical experimental results demonstrated that the as-obtained C60/CoB composite had considerably high storage capacities of 602 mA h/g, which were much higher than those of individual C60 and CoB. Furthermore their hydrogen storage processes and the mechanism have also been investigated.

Enhanced Li Ion Conductivity in LiBH4–Al2O3 Mixture via Interface Engineering

A new solid-state Li ion conductor composed of LiBH4 and Al2O3 was synthesized by a simple ball-milling process. The element distribution map obtained by transmission electron microscopy demonstrates that the LiBH4 and Al2O3 are well mixed and form a large interface after ball-milling. The ionic conductivity of the mixture reaches as high as 2 × 10–4 S cm–1 at room temperature when the volume fraction of Al2O3 is approximately 44%. The ionic conductivity of the interface between LiBH4 and Al2O3 was extracted by using a continuum percolation model, which turns out to be about 10–3 S cm–1 at room temperature, being 105 times higher than that of pure LiBH4. This remarkable rise in conductivity is accompanied by the lowered activation energy for the Li ion conduction in the mixture, indicating that the interface layer facilitates Li ion conduction. Near-edge X-ray absorption fine structure analysis reveals the presence of B–O bondings in the mixture, which was not detected by X-ray diffraction. This disruptio...