TiO₂ Nanobelt@Co₉S₈ Composites as Promising Anode Materials for Lithium and Sodium Ion Batteries

A Multifunctional Coating on Sulfur-Containing Carbon-Based Anode for High-Performance Sodium-Ion Batteries

A sulfur doping strategy has been frequently used to improve the sodium storage specific capacity and rate capacity of hard carbon. However, some hard carbon materials have difficulty in preventing the shuttling effect of electrochemical products of sulfur molecules stored in the porous structure of hard carbon, resulting in the poor cycling stability of electrode materials. Here, a multifunctional coating is introduced to comprehensively improve the sodium storage performance of a sulfur-containing carbon-based anode. The physical barrier effect and chemical anchoring effect contributed by the abundant C-S/C-N polarized covalent bond of the N, S-codoped coating (NSC) combine to protect SGCS@NSC from the shuttling effect of soluble polysulfide intermediates. Additionally, the NSC layer can encapsulate the highly dispersed carbon spheres inside a cross-linked three-dimensional conductive network, improving the electrochemical kinetic of the SGCS@NSC electrode. Benefiting from the multifunctional coating, SGCS@NSC exhibits a high capacity of 609 mAh g^-1 at 0.1 A g^-1 and 249 mAh g^-1 at 6.4 A g^-1. Furthermore, the capacity retention of SGCS@NSC is 17.6% higher than that of the uncoated one after 200 cycles at 0.5 A g^-1.

Synthesis of MnO/C/NiO-Doped Porous Multiphasic Composites for Lithium-Ion Batteries by Biomineralized Mn Oxides from Engineered Pseudomonas putida Cells

A biotemplated cation-incoporating method based on bacterial cell-surface display technology and biogenic Mn oxide mineralization process was developed to fabricate Mn-based multiphasic composites as anodes for Li-ion batteries. The engineered Pseudomonas putida MB285 cells with surface-immobilized multicopper oxidase serve as nucleation centers in the Mn oxide biomineralization process, and the Mn oxides act as a settler for incorporating Ni ions to form aggregates in this process. The assays using X-ray photoelectron spectroscopy, phase compositions, and fine structures verified that the resulting material MnO/C/NiO (CMB-Ni) was porous multiphasic composites with spherical and porous nanostructures. The electrochemical properties of materials were improved in the presence of NiO. The reversible discharge capacity of CMB-Ni remained at 352.92 mAh g^-1 after 200 cycles at 0.1 A g^-1 current density. In particular, the coulombic efficiency was approximately 100% after the second cycle for CMB-Ni.

Low Temperature Deposition of TiO2 Thin Films through Atmospheric Pressure Plasma Jet Processing

Titanium dioxide (TiO2) has been widely used as a catalyst material in different applications such as photocatalysis, solar cells, supercapacitor, and hydrogen production, due to its better chemical stability, high redox potential, wide band gap, and eco-friendly nature. In this work TiO2 thin films have been deposited onto both glass and silicon substrates by the atmospheric pressure plasma jet (APPJ) technique. The structure and morphological properties of TiO2 thin films are studied using different characterization techniques like X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and field emission scanning electron microscopy. XRD study reveals the bronze-phase of TiO2. The XPS study shows the presence of Ti, O, C, and N elements. The FE-SEM study shows the substrate surface is well covered with a nearly round shaped grain of different size. The optical study shows that all the deposited TiO2 thin films exhibit strong absorption in the ultraviolet region. The oleic acid photocatalytic decomposition study demonstrates that the water contact angle decreased from 80.22 to 27.20° under ultraviolet illumination using a TiO2 photocatalyst.

The Progress of Cobalt-Based Anode Materials for Lithium Ion Batteries and Sodium Ion Batteries

Limited by the development of energy storage technology, the utilization ratio of renewable energy is still at a low level. Lithium/sodium ion batteries (LIBs/SIBs) with high-performance electrochemical performances, such as large-scale energy storage, low costs and high security, are expected to improve the above situation. Currently, developing anode materials with better electrochemical performances is the main obstacle to the development of LIBs/SIBs. Recently, a variety of studies have focused on cobalt-based anode materials applied for LIBs/SIBs, owing to their high theoretical specific capacity. This review systematically summarizes the recent status of cobalt-based anode materials in LIBs/SIBs, including Li+/Na+ storage mechanisms, preparation methods, applications and strategies to improve the electrochemical performance of cobalt-based anode materials. Furthermore, the current challenges and prospects are also discussed in this review. Benefitting from these results, cobalt-based materials can be the next-generation anode for LIBs/SIBs.

Preparation of Gd-Doped TiO2 Nanotube Arrays by Anodization Method and Its Photocatalytic Activity for Methyl Orange Degradation

Gd-doped TiO2 nanotube arrays with 3D ordered and high specific surface (176 m2/g) area are successfully prepared on a Ti foil surface via an anodizing method. The characterizations of Gd-doped TiO2 nanotube arrays are carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectrometer (EDX), optical contact angle measurer, and ultraviolet (UV) fluorescence spectrophotometer, respectively. The results reveal that the Gd-doped TiO2 nanotube arrays form on the Ti foil surface with a length of about 50.5 μm and 100 nm in diameter, and the growth direction grown along the (101) direction of anatase crystal. Under the optimized reaction conditions (60 V, 10 h, 0.01mol/L Gd3+), the crystal phase of Gd-doped TiO2 show an excellent nanotube structure, possess a beneficial photocatalytic performance for methyl orange (MO) (Degradation rate was 95.8%) and an excellent hydrophilic property (The optical contact angle was 4.9°). After doping with Gd, the hydrophilic and photocatalytic properties of the TiO2 nanotubes are further improved.

Sulfur-Doped Reduced Graphene Oxide for Enhanced Sodium Ion Pseudocapacitance

Sodium-ion capacitors (NICs) are considered an important candidate for large-scale energy storage in virtue of their superior energy-power properties, as well as availability of rich Na+ reserves. To fabricate high-performance NIC electrode material, a hydrothermal method was proposed to synthesize sulfur-doped reduced graphene oxide (SG), which exhibited unique layered structures and showed excellent electrochemical properties with 116 F/g capacitance at 1 A/g as the cathode of NICs from 1.6 V to 4.2 V. At the power-energy density over 5000 W/kg, the SG demonstrated over 100 Wh/kg energy density after 3500 cycles, which indicated its efficient durability and superior power-energy properties. The addition of a sulfur source in the hydrothermal process led to the higher specific surface area and more abundant micropores of SG when compared with those of reduced graphene oxide (rGO), thus SG exhibited much better electrochemical properties than those shown by rGO. Partially substituting surface oxygen-containing groups of rGO with sulfur-containing groups also facilitated the enhanced sodium-ion storage ability of SG by introducing sufficient pseudocapacitance.

Highly Hydrophilic TiO₂ Nanotubes Network by Alkaline Hydrothermal Method for Photocatalysis Degradation of Methyl Orange

High-density and highly cross-coated anatase TiO₂ nanotubes networks have been successfully prepared on the surface of Ti foil by alkaline hydrothermal using NaOH and Ti foil as the precursors. The nanotubes networks were analyzed using X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDX), transmission electron microscope (TEM), scanning electron microscopy (SEM), optical contact angle tester, and ultraviolet (UV) fluorescence spectrophotometer, respectively. The results showed that the nanotubes network with diameters of 30–50 nm were obtained on the Ti foil surface. The morphology of the nanotubes network possessed the three-dimensional network structure, The TiO₂ nanotubes network grew along the (101) direction of the tetragonal anatase crystal. The morphology and crystal phase of the TiO₂ nanotubes network were better at the conditions of NaOH concentration 7–10 mol/L and temperature 160–170 °C. The best contact angle of TiO₂ nanotubes network after UV-light irradition was only 5.1 ± 2.9°. Under the irradiation of mercury lamp, the nanotubes network exhibited excellent photocatalytic performance and the degradation ratio of methyl orange solution reached to 80.00 ± 2.33%. Thus, the anatase TiO₂ nanotubes network has great potential in applications for pollution photocatalytic degradation.

One-Step Acidic Hydrothermal Preparation of Dendritic Rutile TiO₂ Nanorods for Photocatalytic Performance

Three-dimensional and dendritic rutile TiO₂ nanorods were successfully fabricated on a Ti foil surface using a one-step acidic hydrothermal method. The TiO₂ nanorods were characterized using X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and optical contact angle testing. The results showed that the nanorods with diameters of 100⁻500 nm and lengths of 100 nm to 1 μm were obtained on the Ti foil surface. The length and density of the TiO₂ nanorods were perfect at the conditions of HCl concentration 0.5 mol/L, temperature 220 °C, and reaction time 12 h. The TiO₂ nanorods formed parallel to the consumption of Ti and grew along the (110) direction having a tetragonal rutile crystal. The morphology of the nanorods possessed a three-dimensional structure. The contact angle of the nanorods was only 13 ± 3.1°. Meanwhile, the photocatalytic activities of the TiO₂ nanorods were carried out using ultraviolet fluorescence spectrophotometry for the methyl orange detection, and the degradation was found to be about 71.00% ± 2.43%. Thus, TiO₂ nanorods can be developed by a one-step acidic hydrothermal method using Ti foil simultaneously as the substrate with a TiO₂ source; the TiO₂ nanorods exhibited photocatalytic performance while being environment-friendly.

Three-Dimensional SnS Decorated Carbon Nano-Networks as Anode Materials for Lithium and Sodium Ion Batteries

The three-dimensional (3D) SnS decorated carbon nano-networks (SnS@C) were synthesized via a facile two-step method of freeze-drying combined with post-heat treatment. The lithium and sodium storage performances of above composites acting as anode materials were investigated. As anode materials for lithium ion batteries, a high reversible capacity of 780 mAh·g⁻¹ for SnS@C composites can be obtained at 100 mA·g⁻¹ after 100 cycles. Even cycled at a high current density of 2 A·g⁻¹, the reversible capacity of this composite can be maintained at 610 mAh·g⁻¹ after 1000 cycles. The initial charge capacity for sodium ion batteries can reach 333 mAh·g⁻¹, and it retains a reversible capacity of 186 mAh·g⁻¹ at 100 mA·g⁻¹ after 100 cycles. The good lithium or sodium storage performances are likely attributed to the synergistic effects of the conductive carbon nano-networks and small SnS nanoparticles.