3D GA Research Articles

Stable Cycling of Ultrahigh Mass Loaded MnO2 for Low-Cost Sodium-Ion Batteries

Achieving cost-effective and sustainable solutions for large-scale energy storage is critical for advancing the global clean energy transition. The intermittent nature of green energy underscores the inadequacy of current large scale energy storage technologies like pumped hydroelectricity which is susceptible to geographic and water resource constraints, making batteries a prime candidate for this role. Although lithium-ion batteries (LIBs) with high energy and power density are a viable solution, the high cost and uneven distribution of lithium reserves limits the widespread application of LIBs for grid energy storage. Considering these developments and the challenges posed by limited lithium reserves, sustainable and low-cost sodium-ion batteries (SIBs) emerge as a promising alternative.Among the various battery electrode materials, manganese dioxide (MnO2) stands out as a promising choice for large-scale energy storage applications due to its earth abundance, cost-effectiveness and non-toxic nature. Although MnO2 is known as a pseudocapacitive material with superior cycling stability in aqueous electrolytes, its dissolution in non-aqueous electrolytes has restricted its widespread use in long lifetime batteries. In this study, we demonstrate that an ether-based electrolyte solution (1M NaClO4 in diglyme) is able to achieve stable cycling of electrodeposited ε-MnO2 as a cathode for SIBs, reaching a over 75% capacity retention over 1000 cycles. This response surpasses conventional ester-based electrolytes (58% of 1M NaClO4 in EC/PC). A comparative cycling stability study, coupled with electrochemical quartz crystal microbalance characterization, validates the efficacy of the ether-based electrolyte in mitigating MnO2 dissolution. Furthermore, the integration of 3D printed graphene aerogel (3D GA) as a scaffold for electrodeposited MnO2 leads to enhanced electrochemical performance of the MnO2 electrode (3D MnO2/GA), resulting in a high areal capacity of 4.4 mAh cm-2 at a current density of 10 mA cm-2. The 3D MnO2/GA electrode possesses scalable electrochemical performance with mass loadings from 20 mg cm-2 to 80 mg cm-2. Using this electrode, a high mass loaded sodium-ion battery (SIB) device was fabricated by using utilizing 58 mg cm-2 3D MnO2/GA as the cathode and 16 mg cm-2 dip-coated TiO2@Cu foam as the anode. This MnO2 | TiO2 device delivered a notable areal capacity of 6.2 mWh cm-2 and a high areal power density of 70.7 mW cm-2. Moreover, the SIB device demonstrates 85% capacity retention after 500 cycles, underscoring the stable cycling of this high-energy and power-density SIB device.

Recyclable and dual-functional Ag3PO4/3D graphene aerogel photocatalysts for simultaneous water oxidation and pollutant degradation

Exploiting recyclable and reusable photocatalysts in pollutants elimination and water splitting has drawn extensive research attention for solving the increasing energy and environmental issues. Herein, we designed a high-performance dual functional Ag3PO4/three-dimensional (3D) graphene aerogel (APGA) photocatalyst, in which the 3D GA with extremely lightweight and high mechanical stability served as the support for Ag3PO4 particles, preventing the serious weight loss during the recovery process. Moreover, different from the traditional powder photocatalysts, the application of 3D GA support avoided the secondary contamination caused by the catalyst residue during the reaction. The abundant hydroxyl groups on the surface of porous 3D GA prevented the aggregation of Ag3PO4 particles, forming a close interfacial contact. Profiting from the large number of active sites and high conductivity of 3D GA, the optimized APGA-12 sample showed excellent O2 generation (814.1 μmol·g−1) and synchronous Cr (VI) reduction (87.5 %) efficiency. In addition, the APGA-12 sample also exhibited excellent carbamazepine (CBZ) degradation activity (99 % within 30 min) in the presence of peroxymonosulfate (PMS). Cycling experiments combined with the scaled-up reactions verified the good mechanical and chemical stability of APGA samples. This work provided a promising strategy for solving the problems of catalyst recycling in the field of pollutant degradation and water oxidation.

Clinical reliability and validity of a video-based markerless gait evaluation method.

To explore the reliability and validity of gait parameters obtained from gait assessment system software employing a human posture estimation algorithm based on markerless videos of children walking in clinical practice. Eighteen typical developmental (TD) children and ten children with developmental dysplasia of the hip (DDH) were recruited to walk along a designated sidewalk at a comfortable walking speed. A 3-dimensional gait analysis (3D GA) and a 2-dimensional markerless (2D ML) gait evaluation system were used to extract the gait kinematics parameters twice at an interval of 2 h. The two measurements of the children's kinematic gait parameters revealed no significant differences (P > 0.05). Intra-class correlation coefficients (ICC) were generally high (ICC >0.7), showing moderate to good relative reliability. The standard error of measurement (SEM) values of all gait parameters measured by the two walks were 1.26°-2.91°. The system software had good to excellent validity compared to the 3D GA, with ICC values between 0.835 and 0.957 and SEM values of 0.87°-1.71° for the gait parameters measured by both methods. The Bland-Altman plot analysis indicated no significant systematic errors. The feasibility of the markerless gait assessment method using the human posture estimation-based algorithm may provide reliable and valid gait analysis results for practical clinical applications.

3D‐Printed Graded Electrode with Ultrahigh MnO2 Loading for Non‐Aqueous Electrochemical Energy Storage

AbstractElectrolytic manganese dioxide is one of the promising cathode candidates for electrochemical energy storage devices due to its high redox capacity and ease of synthesis. Yet, high‐loading MnO2 often suffers from sluggish reaction kinetics, especially in non‐aqueous electrolytes. The non‐uniform deposition of MnO2 on a porous current collectors also makes it difficult to fully utilize the active materials at high mass loading. Here, a 3D printed graded graphene aerogel (3D GA) that contains sparsely separated exterior ligaments is developed to create large open channels for mass transport as well as densely arranged interior ligaments providing large ion‐accessible active surface. The unique structural design homogenizes the thickness of electro deposited MnO2 even at an ultrahigh mass loading of ≈70 mg cm−2. The electrode achieves a remarkable volumetric capacity of 29.1 mA h cm−3 in the non‐aqueous electrolyte. A Li‐ion hybrid capacitor device assembled with a graded 3D GA/MnO2 cathode and graded 3D GA/VOx anode exhibits a wide voltage window of 0–4 V and a superior volumetric energy density of 20.2 W h L−1. The findings offer guidance on 3D printed electrode design for supporting ultrahigh loading of active materials and developments of high energy density energy storage devices.

Design of Intrinsically Flame-Retardant Vanillin-Based Epoxy Resin for Thermal-Conductive Epoxy/Graphene Aerogel Composites.

Vanillin, as a lignin-derived mono-aromatic compound, has attracted increasing attention due to its special role as an intermediate for the synthesis of different biobased polymers. Herein, intrinsically flame-retardant and thermal-conductive vanillin-based epoxy/graphene aerogel (GA) composites were designed. First, a bifunctional phenol intermediate (DN-bp) was synthesized by coupling vanillin with 4, 4'-diaminodiphenylmethane and DOPO, and the epoxy monomer (MEP) was obtained by the epoxidation reaction with DN-bp and epichlorohydrin. Then, various amounts of MEP and diglycidyl ether of bisphenol A (DER) were mixed and cured. Interestingly, the flexural strength and modulus were greatly enhanced from 72.8 MPa and 1.3 GPa to 90.3 MPa and 2.8 GPa, respectively, at 30 wt % MEP, due to the rigidity of MEP and strong intermolecular N-H hydrogen bonding interactions. Meanwhile, the cured epoxy achieved a UL-94 V0 rating with a low P content of 1.06%. The flame-retardant vanillin-based epoxy was then impregnated into the thermal conductive 3D GA networks. The obtained epoxy/graphene composite showed excellent flame retardancy and thermal conductivity [λ = 0.592 W/(m·K)] with only 0.5 wt % graphene in the system. Based on these results, we believe that this work would represent a novel solution for the preparation of high-performance biobased flame-retardant multipurpose epoxies.

3D graphene aerogel-supported copper azide nanoparticles as primary explosive with excellent initiation performance

Copper azide (CA), a high energy primary explosive, had been investigated with various supporter materials to reduce its sensitivity characteristics. However, effective supporter had not been designed to fully reduce CAs sensitivity characteristics. Hence, we presented a three-dimensional (3D) graphene aerogel-supported CA (CA-GAs) strategy to meet those needs. CA-GAs was prepared using 3D GA as the framework to uniformly grip CA. The SEM and XRD measurements revealed that CA nanoparticles were fully dispersed on GAs, the in-situ azidation reaction of Cu precursor and CAs crystalline structure were not affected by GAs. DSC further verified the thermal stability of CA-GAs. Moreover, electrostatic ignition experiment was employed to investigate CA-GAs’ ignition time, input energy, and electrical ignition performance. Those results showed that CA-GAs could be reliably detonated by a 3.5 [Formula: see text] SCB, the average electric ignition voltage, ignition time, and input energy of CA-GAs were 19.125 V, 21 [Formula: see text]s, and 0.56 mJ, respectively. All these results illustrated that GAs was an effective supporter for the stabilization of CA.

MOF-derived Co9S8/C hollow polyhedra grown on 3D graphene aerogel as efficient polysulfide mediator for long-life Li-S batteries

Lithium-sulfur (Li-S) batteries are considered as one of the most promising candidates for next-generation energy storage systems because of their high energy density. However, rapid capacity fade and low sulfur content caused by the shuttle effect of soluble lithium polysulfides (LiPSs) and the low conductivity of sulfur hinder the practical applications of Li-S batteries. In this regard, we synthesized metal-organic framework (MOF)-derived Co9S8/C hollow polyhedra grown on three-dimensional graphene aerogel (3D GA) as an efficient sulfur host material. The highly porous, conductive and free-standing 3D GA framework enables high sulfur content (77.3 wt%). The polar Co9S8/C provides strong chemical binding to immobilize polysulfides, and suppress the shuttling effect. Significantly, the Co9S8/C/GA/S cathode exhibits excellent long cycling stability with a low capacity decay rate of 0.0473% per cycle over 400 cycles.

Freestanding 3D MoS2 nanosheets/graphene aerogel heterostructure as a recyclable photocatalyst for efficiently degrading antibiotic residues

To develop the high-efficient visible-light photocatalyst with good recyclability is curial for its application in environment remediation. Herein, three-dimensional (3D) MoS2 nanosheet/graphene aerogel (MoS2 NS/GA) has been prepared by using 3D GA as the framework from the hydrothermal method. The prepared 3D MoS2 NS/GA is characterized and shows, even a small amount, high efficiency for photodegrading the concentrated TC-HCl. Moreover, the lost activity could be recovered by the compensation with S2− ions.

Defining gait patterns using Parallel Factor 2 (PARAFAC2): A new analysis of previously published data

Three-dimensional gait analysis (3D–GA) is commonly used to answer clinical questions of the form “which joints and what variables are most affected during when”. When studying high-dimensional datasets, traditional dimension reduction methods (e.g. principal components analysis) require “data flattening”, which may make the ensuing solutions difficult to interpret. The aim of the present study is to present a case study of how a multi-dimensional dimension reduction technique, Parallel Factor 2 (PARAFAC2), provides a clinically interpretable set of solutions to typical biomechanical datasets where different variables are collected during walking and running. Three-dimensional kinematic and kinetic data used for the present analyses came from two publicly available datasets on walking (n = 33) and running (n = 28). For each dataset, a four-dimensional array was constructed as follows: Mode A was time normalized cycle points; mode B was the number of participants multiplied by the number of speed conditions tested; mode C was the number of joint degrees of freedom, and mode D was variable (angle, velocity, moment, power). Five factors for walking and four factors for running were extracted which explained 79.23% and 84.64% of their dataset’s variance. The factor which explains the greatest variance was swing-phase sagittal plane knee kinematics (walking), and kinematics and kinetics (running). Qualitatively, all extracted factors increased in magnitude with greater speed in both walking and running. This study is a proof of concept that PARAFAC2 is useful for performing dimension reduction and producing clinically interpretable solutions to guide clinical decision making.

Mesoporous Sn4P3-graphene aerogel composite as a high-performance anode in sodium ion batteries

Sodium ion batteries (SIBs) are deemed as the potential alternative for lithium ion batteries (LIBs) in the application of large-scale energy storage and conversion. The favorable anode materials play an important role for high-performance SIBs. Sn4P3 has been considered as one of the promising anode materials for sodium ion batteries due to the combination of high electrical conductivity from Sn and high specific capacity from P. In this work, Sn4P3/graphene aerogel (Sn4P3-GA) composite is prepared via a rapid low-temperature phosphidation reaction from SnO2-GA composite. The structural and morphological characterizations demonstrate that the Sn4P3 nanoparticles with an average size of 8 nm are uniformly and tightly embedded on the surface of 3D GA. The unique 3D network structure as well as the synergistic effect between graphene nanosheets and Sn4P3 nanoparticles would endow the as-prepared Sn4P3-GA composite with good electrochemical sodium storage performance. It delivers the high initial discharge capacity of 1180 mAh g−1 at 0.1 A g−1 and good cycle stability (657 mAh g−1 at 0.1 A g−1 after 100 cycles). Meanwhile, the Sn4P3-GA composite exhibits high-rate capacity of 462 and 403 mAh g−1 at a current density of 1 and 2 A g−1, respectively. Moreover, the contribution of the pseudocapacitance capacity can explicate the origin of good rate capability of the Sn4P3-GA composite. This work demonstrates the great potential of Sn4P3-GA composite as an alternative anode material for the low-cost and high-performance sodium ion batteries.

Knee joint sagittal plane movement in cerebral palsy: a comparative study of 2-dimensional markerless video and 3-dimensional gait analysis

Background and purpose — Gait analysis is indicated in children with cerebral palsy (CP) to identify and quantify gait deviations. One particularly difficult-to-treat deviation, crouch gait, can progress in adolescence and ultimately limit the ability to ambulate. An objective quantitative assessment is essential to early identify progressive gait impairments in children with CP. 3-dimensional gait analysis (3D GA) is considered the gold standard, although it is expensive, seldom available, and unnecessarily detailed for screening and follow-up. Simple video assessments are time-consuming when processed manually, but more convenient if used in conjunction with video processing algorithms; this has yet been validated in CP. We validate a 2-dimensional markerless (2D ML) assessment of knee joint flexion/extension angles of the gait cycle in children and young adults with CP.Patients and methods — 18 individuals, mean age 15 years (6.5–28), participated. 11 had bilateral, 3 unilateral, 3 dyskinetic, and 1 ataxic CP. In the Gross Motor Function Classification System, 6 were at level I, 11 at level II, and 1 at level III. We compared 2D ML, using a single video camera with computer processing, and 3D GA.Results — The 2D ML method overestimated the knee flexion/extension angle values by 3.3 to 7.0 degrees compared with 3D GA. The reliability within 2D ML and 3D GA was mostly good to excellent.Interpretation — Despite overestimating, 2D ML is a reliable and convenient tool to assess knee angles and, more importantly, to detect changes over time within a follow-up program in ambulatory children with CP.

A novel enzyme-free glucose and H2O2 sensor based on 3D graphene aerogels decorated with Ni3N nanoparticles

In this work, a novel enzyme-free glucose and hydrogen peroxide (H2O2) sensor based on Ni3N nanoparticles on conductive 3D graphene aerogels (Ni3N/GA) has been successfully synthesized by using hydrothermal reaction, freeze-dried and then calcined under NH3 atmosphere. The obtained Ni3N/GA composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption isotherms and electrochemical methods. The results show the obtained 3D Ni3N/GA composites exhibit excellent electrochemical performance toward glucose oxidation and H2O2 reduction with larger catalytic rate constant Kcat value of 3.75 × 103 M−1 s −1 and 1.24 × 103 M−1 s −1, respectively. As a glucose sensor, the obtained electrode provides a wide detection range of 0.1–7645.3 μM, fast response time within 3 s, high sensitivity of 905.6 μA mM-1 cm-2 and low detection limit of 0.04 μM. For detection of H2O2, this prepared sensor offers a wide detection range (5 μM–75.13 mM), fast response time (within 5 s), sensitivity (101.9 μA mM-1 cm-2) and low detection limit (1.80 μM). This enzyme-free glucose and H2O2 sensor display satisfactory selectivity, reproducibility and long-term storage stability. Additionally, the sensor can also be used for glucose and H2O2 detection in human blood serum. The results demonstrate that 3D GA nanostructures provide an enviable conductive network for efficient charge transfer and avoid Ni3N nanoparticles aggregation, which is advantageous for electrocatalytic applications.

3D graphene aerogels-supported Ag and Ag@Ag3PO4 heterostructure for the efficient adsorption-photocatalysis capture of different dye pollutants in water

In this paper, we successfully synthesized 3D graphene aerogels-supported Ag and Ag@Ag3PO4 heterostructure (3D Ag/Ag@Ag3PO4/GA) by the hetero-growth of Ag3PO4 on partly Ag nanoparticles in macroporous 3D graphene aerogels (3D GA), aiming for the efficient adsorption-photocatalysis capture of both cationic (RhB, MB, and NR) and anionic (MO) dyes from aqueous solutions. For the removal of different dyes, the contributions of adsorption and photocatalysis is different and the apparent removal sequence is NR > RhB > MB > MO on the prepared 3D Ag/Ag@Ag3PO4/GA. Compared with bare Ag3PO4 particles, Ag3PO4/GO, and Ag/Ag@Ag3PO4/GO, the prepared 3D Ag/Ag@Ag3PO4/GA exhibits the highest catalytic activities for the visible light degradation of RhB and MO. The possible mechanism for improved photocatalytic degradation of dyes by the 3D Ag/Ag@Ag3PO4/GA is proposed based on the active species trapping experiments. Moreover, the good stability and convenient recycling of the prepared 3D Ag/Ag@Ag3PO4/GA composite further make it have potential application prospect in eliminating organic contaminants.

Training for mobility with exoskeleton robot in spinal cord injury patients: a pilot study.

Wearable robots are people-oriented robots designed to be worn all day, thus helping in the daily activities. They can assist in walking, running, jumping higher or even lifting objects too heavy in normal conditions. The aim of this report was to investigate the changes in gait pattern through 3D gait analysis of subjects with spinal cord injury (SCI) undergoing an adaptive training with a wearable exoskeletal device (ESD). The change in the quality of life was also investigate together with the possibility to wear these devices all day, to improve the mobility. Prospective quasi-experimental study, pre- and post-design. Outpatient SCI patients. On a voluntary basis, eight SCI patients who had never used any ESD device were recruited. Subjects underwent a three-dimensional gait analysis (3D GA) while wearing the ESD at baseline (inclusion) (T0) and after 20 sessions of training over an expected average of 5/6 weeks (T1). The secondary outcome measures were: Participant Satisfaction Questionnaire, 6-Minute Walking Test (6MWT), Borg Scale (the test was administered in indoor and outdoor conditions) and Timed Up-and-Go test (TUG). Spatiotemporal and kinematic parameters were assessed and their change from the beginning to the end of the training was the secondary outcome. No dropouts were recorded during the training and all subjects were able to terminate the protocol (compliant subjects: N.=8). After the training, all person showed some significant improvements for TUG, 6MWT and 10 MWT (Z=-2.521; P=0.008) and for the spatiotemporal and kinematics parameters. This paper confirms that the adaptive training with ESD is safe and feasible in a heterogeneous sample of persons with SCI, especially in ameliorating the interaction between the patients and the device with an improvement of spatiotemporal and kinematics parameters. Since the training has been proven safe and the hypothesis that the subjects with spinal cord injury improving their performance over time and being able to adapt at the use of device in full autonomy at home during all the activities of the daily living has strengthened.

Three-dimensional Au nanoparticles/nano-poly(3,4-ethylene dioxythiophene)- graphene aerogel nanocomposite: A high-performance electrochemical immunosensing platform for prostate specific antigen detection

Conductive poly(3,4-ethylenedioxythiophene) (PEDOT) composites have emerged as potential candidates for electrochemical biosensors, however, the sensing performance was mainly relied on their structure and composition. In this work, a novel three-dimensional (3D) structural nano-PEDOT-graphene aerogel (nano-PEDOT-GA) composite was designed via the in-situ polymerization of nano-PEDOT on porous 3D GA. SEM revealed that the introduction of GA could induce the growth of worm-like PEDOT. Subsequently, Au nanoparticles (AuNPs) were directed to nano-PEDOT-GA surface by electrodeposition method. Featuring the excellent biocompatibility, high specific surface area and good conductivity of AuNPs/nano-PEDOT-GA, a highly sensitive label-free immunosensor was developed using AuNPs/nano-PEDOT-GA as signal amplification platform for detecting prostate specific antigen (PSA). Under the optimal conditions, the fabricated immunosensor presented a good linear in the analytical range of 0.0001–50 ng mL−1 with a low detection limit of 0.03 pg mL−1 (S/N = 3), high selectivity against other serum interfering substance and good stability and reproducibility, which provides a promising platform for the clinical immunoassay of PSA.

3D Network and 2D Paper of Reduced Graphene Oxide/Cu2O Composite for Electrochemical Sensing of Hydrogen Peroxide.

In this study, two-dimensional (2D) and three-dimensional (3D) freestanding reduced graphene oxide-supported Cu2O composites (Cu2O-rGO) were synthesized via simple and cost-efficient hydrothermal and filtration strategies. The structural characterizations clearly showed that highly porous 3D graphene aerogel-supported Cu2O microcrystals (3D Cu2O-GA) have been successfully synthesized, and the Cu2O microcrystals are uniformly assembled in the 3D GA. Meanwhile, paper-like 2D reduced graphene oxide-supported Cu2O nanocrystals (2D Cu2O-rGO-P) have also been prepared by a filtration process. It was found that the products prepared from different precursors and methods exhibited different sensing performances for H2O2 detection. The electrochemical measurements demonstrated that the 3D Cu2O-GA has high electrocatalytic activity for the H2O2 reduction and excellent sensing performance for the electrochemical detection of H2O2 with a detection limit of 0.37 μM and a linear detection range from 1.0 μM to 1.47 mM. Meanwhile, the 2D Cu2O-rGO-P structure also showed good electrochemical sensing performance toward H2O2 detection with a much wider linear response over the concentration range from 5.0 μM to 10.56 mM. Compared to the previously reported sensing materials, the as-obtained 2D and 3D Cu2O-rGO materials exhibited higher electrochemical sensing properties toward the detection of H2O2 with high sensitivity and selectivity. The 2D and 3D Cu2O-rGO composites also exhibited high sensing performance for the real-time detection of H2O2 in human serum. The present study indicates that 2D and 3D graphene-Cu2O composites have promising applications in the fabrication of nonenzymatic electrochemical sensing devices.

Programmed amputation on a teenager: What kind of preparation for what outcome?

Traumatic lower limb amputation is rare in pediatric population, and surgeons always try limb salvage. But rarely, later amputation occurred when the traumatic limb is painful. It is a difficult and irreversible decision needed a multidisciplinary approach. We report how we managed a programmed trans-tibial amputation on 13-years-old boy, 20 months after a foot trauma. Our patient is an adolescent victim of a left foot crash. The first checkup showed a degloving injury, dislocation of the interphalangeal joints and of all toes. Foot salvage was decided, but necrotic evolution required minor distal amputation and frequent dressings and skin grafts. Despite physiotherapy, orthosis (anti-equinus orthosis, orthopedics sole, orthopedics shoes) an equinus appeared. Moreover, he presented intense neuropathic foot pain, which required drugs, TENS and psychologic counseling. The foot presented secondary ulcerations requiring surgical cushioning. Seventeen months after trauma, the boy presented a painful, non-functional and ulcerative foot with important impact on quality of life (QOL). After multidisciplinary consultations, the boy and his parents decided a trans-tibial left amputation. A specific multidisciplinary preparation lasted 3 months: he met amputees, psychologist with and without his mother, certified prosthetist orthoptist, specialists of physical and functional rehabilitation, pediatric surgeon. Twenty months after trauma, trans-tibial amputation was carried out. One month after amputation: he walked with crutches, 3 months after: walked and could walks up and down the stairs. One year after: he had no pain, took no drug, got a satisfied gait on quantitative 3D gait analysis (3D GA), practices several sports, says that he has a “normal” teenager life, has an objective “normal” participation. There is no case on literature reported on late amputation on child after a trauma. So, there is no recommendations to prepare amputation or to know what can we expected from it. We report a specific preparation and objective results (QGA, participation, QOL). This experience can be useful for team facing this particular and difficult situation.

Self-Assembled 3D Graphene Monolith from Solution.

Three-dimensional (3D) graphene-assembled monoliths (GAs), especially ones prepared by self-assembly in the liquid phase, represent promising forms to realize the practical applications of graphene due to their high surface utilization and operability. However, the understanding of the assembly process and structure control of 3D GAs, as a new class of carbon materials, is quite inadequate. In this Perspective, we give a demonstration of the assembly process and discuss the key factors involved in the structure control of 3D GAs to pave the way for their future applications. It is shown that the assembly process starts with the phase separation, which is responsible for the formation of the 3D networked structure and liquid phase as the spacers avoid the parallel overlap of graphene layers and help form an interlinked pore system. Well-tailored graphene sheets and selected assembly media must be a precondition for a well-controlled assembly process and microstructure of a 3D GA. The potential applications in energy storage featuring high rate and high volumetric energy density demonstrate advantages of 3D GAs in real applications.

Distinctive electronic structure, unusual magnetic properties and large enhancement in SERS of 1D gallium nanoribbons achieved by doping calix[6]arene

The present work provides a novel route for forming one-dimensional (1D) gallium (Ga) nanoribbon materials with a host molecule calix[6]arene (CA-6) as a template by a facile, one-step and low temperature chemical bath method. Field-emission scanning electron microscopy and transmission electron microscopy showed that the uniform 1D Ga nanoribbon material (Ga-a) can be constructed only in the presence of CA-6, and the formation of ribbon structures is highly dependent on doping ratios and deposition times. Our data indicate that the unusual effect of CA-6 is due to a combination of two factors: a high density of OH groups in the outer surface of its cavity and an appropriate cavity diameter. Especially, the uniform 1D Ga nanoribbon material exhibits a distinct electronic structure and very rare magnetic behaviour when compared to those 3D Ga materials obtained by means of other host molecules: calix[4]arene, γ-cyclodextrin and 18-crown-6. For example, of all the Ga materials, the uniform 1D nanoribbon material has the lowest electron density of Ga core levels in light of X-ray photoelectron spectroscopy analysis. This result suggests that there is a stronger molecule–atom interaction between Ga atoms and CA-6 molecules compared with those in other host–guest systems. More importantly, the uniform 1D Ga nanoribbon material exhibits a magnetic transformation from a diamagnetic to a paramagnetic state under the influence of an applied field, which is completely different from those of all the 3D Ga materials and all the irregular Ga nanoribbon materials. Such a transformation is novel in metals and particularly useful in the chemistry of materials since it allows dramatic modifications of magnetic properties of metal nanocrystals. Finally, a strong surface-enhanced Raman scattering of the uniform 1D Ga nanoribbon material has been observed for organic molecules adsorbed on their surface. Taken together, we believe this work opens a new channel for development of 1D metal-based nanomaterials.

Nanoscale Electrodeposition of Ga on Au(111) from Ionic Liquids

Electrocrystallization of Ga on Au(111) in two different ionic liquid electrolytes has been investigated by in situ electrochemical STM imaging with partly nanometer resolution. In chlorogallate-containing melts underpotential deposition (UPD) leads to surface alloying whereby a Ga−Au surface layer is formed on top of Au(111). In AlCl3−[C4mim]Cl + 5 mM GaCl3 melts, 2D-electrochemical phase formation is driven by conventional nucleation and growth of 2D Ga islands. Prior to the UPD processes anion adsorption of GaCl4− and AlCl4−, respectively, occurs which is characterized by well-ordered anion layer structures with comparable lattice constants. At potentials negative of the UPD region, 3D Ga clusters are formed. On the basis of their shape and the coexistence of small and large clusters in contact, it is concluded that the clusters in the size range 5−30 nm are solid. Taking into account that the temperatures during electrodeposition ranged up to 313 K—above the melting point of α-Ga of 303 K—this observation is remarkable.