Silicon-based material is considered to be one of the most promising anodes for the next-generation lithium-ion batteries (LIBs) due to its rich sources, non-toxicity, low cost and high theoretical specific capacity. However, it cannot maintain a stable electrode structure during repeated charge/discharge cycles, and therefore long cycling life is difficult to be achieved. To address this problem, herein a simple and efficient method is developed for the fabrication of an integrated composite anode consisting of SiO-based active material and current collector, which exhibits a core–shell structure with nitrogen-doped carbon coating on SiO/P micro-particles. Without binder and conductive agent, the volume expansion of SiO active material in the integrated composite anode is suppressed to prevent its pulverization. At a current density of 500 mA·g−1, this integrated composite anode exhibits a reversible specific capacity of 458 mA·h·g−1 after 200 cycles. Furthermore, superior rate performance and cycling stability are also achieved. This work illustrates a potential method for the fabrication of integrated composite anodes with superior electrochemical properties for high-performance LIBs.
FeS2 has drawn tremendous attention as electrode material for sodium-ion batteries (SIBs) due to its high theoretical capacity and abundant resources. However, it suffers from severe volume expansion and dull reaction kinetics during the cycling process, leading to poor rate capacity and short cyclability. Herein, a well-designed FeS2@C/G composite constructed by FeS2 nanoparticles embedded in porous carbon nanorods (FeS2@C) and covered by three-dimensional (3D) graphene is reported. FeS2 nanoparticles can shorten the Na+ diffusion distance during the sodiation–desodiation process. Porous carbon nanorods and 3D graphene not only improve conductivity but also provide double protection to alleviate the volume variation of FeS2 during cycling. Consequently, FeS2@C/G exhibits excellent cyclability (83.3% capacity retention after 300 cycles at 0.5 A·g−1 with a capacity of 615.1 mA·h·g−1) and high rate capacity (475.1 mA·h·g−1 at 5 A·g−1 after 2000 cycles). The pseudocapacitive process is evaluated and confirmed to significantly contribute to the high rate capacity of FeS2@C/G.
Lithium–sulfur batteries are considered to be one of the strong competitors to replace lithium-ion batteries due to their large energy density. However, the dissolution of discharge intermediate products to the electrolyte, the volume change and poor electric conductivity of sulfur greatly limit their further commercialization. Herein, we proposed a self-supporting cathode of nickel-decorated TiO2 nanotube arrays (TiO2 NTs@Ni) prepared by an anodization and electrodeposition method. The TiO2 NTs with large specific surface area provide abundant reaction space and fast transmission channels for ions and electrons. Moreover, the introduction of nickel can enhance the electric conductivity and the polysulfide adsorption ability of the cathode. As a result, the TiO2 NTs@Ni–S electrode exhibits significant improvement in cycling and rate performance over TiO2 NTs, and the discharge capacity of the cathode maintains 719 mA·h·g−1 after 100 cycles at 0.1 C.
Size-constrained ultrathin BiOCl nanosheets@C composites were achieved by one-step hydrothermal route. It was found that the carbon coated on the surface of BiOCl nanosheets not only accelerated the separation of electrons and holes, but also restricted the outward growth of the BiOCl crystal structure to expose more active catalytic sites. In addition, the obtained composites have stable and close interface contact, beneficial for the structural stability of products as well as the rapid charge transfer. The average sheet thickness was in the range of 20–60 nm. Compared with the ability for pure BiOCl to degrade RhB, the degradation rate of the optimal composite can reach 100% within 15 min, while the corresponding photocurrent intensity could reach 5.6 μA·cm−2, and its impedance value was also the smallest. The removal experiments of active substances showed that h+ and ∙O2− play important roles in the process of photocatalytic degradation. It can be expected that the resulted composites in this work can be used as potential materials for photocatalytic and photoelectrochemical applications.
Defect-rich hierarchical sponge-like TiO2 nanoparticles were successfully synthesized via the combined one-step hydrothermal method and chemical reduction approach. SEM and TEM images showed their porous structure densely packed with even smaller TiO2 particles, while photocatalytic results manifested their superior photocatalytic performance and high stability. The RhB solution (10 ppm) could be absolutely degraded in 60 min, and the degradation rate was twice that of the sample without the treatment by NaBH4. Besides, the TC solution (10 ppm) could be removed by 74.3% in 20 min. PEC measurements also displayed that the photoelectrode based on such defect-rich TiO2 nanoparticles had small resistance and improved charge transfer rate. The improved performance can be assigned to rich defects and phase junctions, which was supported by characterization results. The presence of rich defects and phase junctions could not only promote the separation of photogenerated charge carriers, but also accelerate the electron transfer, beneficial for both the photocatalytic and the PEC performance. It is expected that the obtained hierarchical sponge-like TiO2 nanoparticles with rich defects have great potential for photocatalytic applications.
A number of industrial and biomedical fields, such as hydraulic fracturing balls for gas and petroleum exploitation and implant materials, require Mg alloys with rapid dissolution. An iron-bearing phosphate chemical conversion (PCC) coating with self-catalytic degradation function was fabricated on the Mg alloy AZ31. Surface morphologies, chemical compositions and degradation behaviors of the PCC coating were investigated through FE-SEM, XPS, XRD, FTIR, electrochemical and hydrogen evolution tests. Results indicated that the PCC coating was characterized by iron, its phosphates and hydroxides, amorphous Mg(OH)2 and Mg3−n(HnPO4)2. The self-catalytic degradation effects were predominately concerned with the Fe concentration, chemical composition and microstructure of the PCC coating, which were ascribed to the galvanic corrosion between Fe in the PCC coating and the Mg substrate. The coating with higher Fe content and porous microstructure exhibited a higher degradation rate than that of the AZ31 substrate, while the coating with a trace of Fe and compact surface disclosed a slightly enhanced corrosion resistance for the AZ31 substrate.
Polycyclic aromatic hydrocarbons with zigzag peripheries are high perspective candidates for organic electronics. However, large fused acenes are still poorly studied due to the tedious synthesis. Herein we report a non-substituted fused bistetracene DBATT (2.3,8.9-dibenzanthanthrene) as the semiconductor on low-voltage-driven organic thin-film transistors. The systematic studies of thin-film growth on various self-assembled monolayer (SAM) modified gate dielectrics and the electrical performances were carried out. The sub-monolayer of the semiconductor film shows larger island domains on the alkyl chain SAM. This device exhibits the hole mobility of 0.011 cm2·V−1·s−1 with a current ratio of Ion/Ioff above 105.
Fast and broadband photoelectric detection is a key process to many photoelectronic applications, during which the semiconductor light absorber plays a critical role. In this report, we prepared Cu–In–Zn–S (CIZS) nanospheres with different compositions via a facile hydrothermal method. These nanospheres were ~200 nm in size and comprised of many small nanocrystals. A photodetector responded to the visible spectrum was demonstrated by spraying the solution processed nanospheres onto gold interdigital electrodes. The photoelectric characterization of these devices revealed that CIZS nanospheres with low molar ratio of n(Cu)/n(In) exhibited improved photoelectric response compared to those with high n(Cu)/n(In), which was attributed to the reduced defects. The relatively large switching ratio (Ion/Ioff), fast response and wide spectral coverage of the CIZS-based photodetector render it a promising potential candidate for photoelectronic applications.
Low-dimensional halide perovskites (HPs) have received considerable attention in recent years due to their novel physical properties such as compositional flexibility, high quantum yield, quantum size effects and superior charge transport. Here we show room temperature solution synthesis of 1D organic–inorganic lead bromide perovskite microwires (MWs). Our method uses acetone as a reactant, and when CH3NH3PbBr3 is immersed, acetone reacts with CH3NH3+ cations in the CH3NH3PbBr3 single crystal by the dehydration condensation. The reaction generates a large (CH3)2C=NHCH3+ A-site which cannot be accommodated by the cuboctahedron formed by the corner-sharing [PbBr6]4− octahedral, leading to the transition of corner-sharing octahedra to face-sharing triangular prism and the crystal structure transformation from 3D to 1D. The formation process of (CH3)2C=NHCH3PbBr3 MWs does not involve any ligands, templates or catalysts. A two-terminal memory device was constructed using the (CH3)2C=NHCH3PbBr3 MWs, showing great potential of the method in fabrication of electronic and optoelectronic devices.
Development of porous materials with anti-fouling and remote control- lability is highly desired for oil–water separation application yet still challenging. Herein, to address this challenge, a sponge with unusual superhydrophilicity/superoleophobicity and magnetic property was fabricated through a dip-coating process. To exploit its superhydrophilic/superoleophobic property, the obtained sponge was used as a reusable water sorbent scaffold to collect water from bulk oils without absorbing any oil. Owing to its magnetic property, the sponge was manipulated remotely by a magnet without touching it directly during the whole water collection process, which could potentially lower the cost of the water collection process. Apart from acting as a water-absorbing material, the sponge can also be used as affiliation material to separate water from oil–water mixture and oil in water emulsion selectively, when fixed into a cone funnel. This research provides a key addition to the field of oil–water separation materials.