TiO 2 (B) nanowire arrays on Ti foil substrate as three-dimensional anode for lithium-ion batteries

MXene-Based Current Collectors for Advanced Rechargeable Batteries

As an indispensable component of rechargeable batteries, the current collector plays a crucial role in supporting the electrode materials and collecting the accumulated electrical energy. However, some key issues, like uneven resources, high weight percentage, electrolytic corrosion, and high-voltage instability, cannot meet the growing need for rechargeable batteries. In recent years, MXene-based current collectors have achieved considerable achievements due to its unique structure, large surface area, and high conductivity. The related research has increased significantly. Nonetheless, a comprehensive review of this area is seldom. Herein the applications and progress of MXene in current collector are systematically summarized and discussed. Meanwhile, some challenges and future directions are presented.

Nanostructured TiO2 Arrays for Energy Storage

Because of their extensive specific surface area, excellent charge transfer rate, superior chemical stability, low cost, and Earth abundance, nanostructured titanium dioxide (TiO₂) arrays have been thoroughly explored during the past few decades. The synthesis methods for TiO₂ nanoarrays, which mainly include hydrothermal/solvothermal processes, vapor-based approaches, templated growth, and top-down fabrication techniques, are summarized, and the mechanisms are also discussed. In order to improve their electrochemical performance, several attempts have been conducted to produce TiO₂ nanoarrays with morphologies and sizes that show tremendous promise for energy storage. This paper provides an overview of current developments in the research of TiO₂ nanostructured arrays. Initially, the morphological engineering of TiO₂ materials is discussed, with an emphasis on the various synthetic techniques and associated chemical and physical characteristics. We then give a brief overview of the most recent uses of TiO₂ nanoarrays in the manufacture of batteries and supercapacitors. This paper also highlights the emerging tendencies and difficulties of TiO₂ nanoarrays in different applications.

Development of Bronze Phase Titanium Dioxide Nanorods for Use as Fast-Charging Anode Materials in Lithium-Ion Batteries

Bronze phase titanium dioxide (TiO₂(B)) nanorods were successfully prepared via a hydrothermal method together with an ion exchange process and calcination by using anatase titanium dioxide precursors in the alkali hydrothermal system. TiO₂ precursors promoted the elongation of nanorod morphology. The different hydrothermal temperatures and reaction times demonstrated that the synthesis parameters had a significant influence on phase formation and physical morphologies during the fabrication process. The effects of the synthesis conditions on the tailoring of the crystal morphology were discussed. The growth direction of the TiO₂(B) nanorods was investigated by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The as-synthesized TiO₂(B) nanorods obtained after calcination were used as anode materials and tested the efficiency of Li-ion batteries. This research will study the effects of particle morphologies and crystallinity of TiO₂(B) derived from a modified hydrothermal method on the capacity and charging rate of the Li-ion battery. The TiO₂(B) nanorods, which were synthesized by using a hydrothermal temperature of 220 °C for 12 h, presented excellent electrochemical performance with the highest Li storage capacity (348.8 mAh/g for 100 cycles at a current density of 100 mA/g) and excellent high-rate cycling capability (a specific capacity of 207.3 mAh/g for 1000 cycles at a rate of 5000 mA/g).

Hydrothermally synthesized titanate nanomaterials for the removal of heavy metals and radionuclides from water: A review

Hazardous heavy metals and radionuclides in water and wastewater are of drastic concern owing to their detrimental impacts on the organisms as well as the circumambient ecosystem. To remove them as much as we can, both technique and materials were studied in the past years. The adsorption technique as superior water remediation method with the simplicity of design, environmental friendliness and high efficiency was well established. Consequently, it is practically important to explore advanced and economically feasible absorbents for removing these poisonous pollutants from aqueous solutions. So far, large numbers of experiments proved hydrothermally synthesized titanate nanomaterials (TNMs) could be a prospectively excellent adsorbent extracting heavy metals and radionuclides from water due to the high specific surface area, tunable pore size, abundant surface active sites, favorable hydrophilic properties. The objective of this work is to give an overview of hydrothermal synthesis, adsorption performance of TNMs for heavy metals and radionuclides, as well as the various influencing factors for water purification. It comprehensively reviews the structural changes and regenerability of TNMs after adsorption, and different modification methods adopted for improving removal capacity. Additionally, it uniquely highlights the efficient decontamination of the pollutants through a synergistic effect of adsorption and photocatalysis by TNMs. This review provides detailed information for the development, application, and research challenges faced by hydrothermally synthesized TNMs for the removal of heavy metals and radionuclides from aqueous solutions, which will serve as a reference guide for scientists in related fields.

Rationally designed C/Co9S8@SnS2 nanocomposite as a highly efficient anode for lithium-ion batteries

Nanostructured transition metal sulfides are promising anode materials for lithium-ion batteries. Nevertheless, it is still a great challenge to prepare capacity-improved electrodes without reducing their rate capability and cycle stability. In this paper, we present a C/Co₉S₈@SnS₂ composite material by loading SnS₂ nanocrystals onto MOF-derived C/Co₉S₈ nanostructures. The C/Co₉S₈@SnS₂ composite has multiple active sites to store lithium ions. The specific capacity reaches 3.1 mAh cm^-2 when the current density is 0.224 mA cm^-2. The asynchronous electrochemical reaction between Co₉S₈ and SnS₂ offsets the volume expansion of the anode material. Meanwhile, the compact adhesion of carbon layers on the interfaces suppresses the destruction of the anode during the charging-discharging processes. Consequently, the synthesized electrode presents favorable capacity with high current density or under long-term cycling conditions. The prepared battery has a reversible specific capacity of 0.452 mAh cm^-2 and a coulomb efficiency of 99.7% after 500 cycles with a high current density of 2.24 mA cm^-2. The research results obtained in this work provides a feasible strategy to improve the performance of electrodes systematically.

Ti-Based Oxide Anode Materials for Advanced Electrochemical Energy Storage: Lithium/Sodium Ion Batteries and Hybrid Pseudocapacitors

Titanium-based oxides including TiO₂ and M-Ti-O compounds (M = Li, Nb, Na, etc.) family, exhibit advantageous structural dynamics (2D ion diffusion path, open and stable structure for ion accommodations) for practical applications in energy storage systems, such as lithium-ion batteries, sodium-ion batteries, and hybrid pseudocapacitors. Further, Ti-based oxides show high operating voltage relative to the deposition of alkali metal, ensuring full safety by avoiding the formation of lithium and sodium dendrites. On the other hand, high working potential prevents the decomposition of electrolyte, delivering excellent rate capability through the unique pseudocapacitive kinetics. Nevertheless, the intrinsic poor electrical conductivity and reaction dynamics limit further applications in energy storage devices. Recently, various work and in-depth understanding on the morphologies control, surface engineering, bulk-phase doping of Ti-based oxides, have been promoted to overcome these issues. Inspired by that, in this review, the authors summarize the fundamental issues, challenges and advances of Ti-based oxides in the applications of advanced electrochemical energy storage. Particularly, the authors focus on the progresses on the working mechanism and device applications from lithium-ion batteries to sodium-ion batteries, and then the hybrid pseudocapacitors. In addition, future perspectives for fundamental research and practical applications are discussed.

Carboxyl functionalized carbon incorporation of stacked ultrathin NiO nanosheets: topological construction and superior lithium storage

Two-dimensional (2D) nanostructure engineering and surface modification with functional groups are of great importance to anode materials for rechargeable lithium-ion batteries. Herein, stacked NiO nanosheets@carbon (denoted as NiO@C) and 3 nm-ultrathin NiO nanosheets@functionalized carbon with surface functional groups NO3-, CO32-, OH-, and COOH- (denoted as NiO@FC) were prepared via a facile one-pot reaction and topotactic conversion. Specifically, NiO@FC exhibits excellent lithium storage performance: the capacity of NiO@FC is 489.2 mA h g-1, higher than that of NiO@C (1018.7 mA h g-1 at 0.2 A g-1), and maintains a capacity of 1133 mA h g-1 after 800 cycles, which exceed that of all previously reported NiO anodes. The enhanced lithium storage performance is attributed to the sufficient void space, which offers buffer space for volume change and speeds up the diffusion of Li+ ions. In addition, the surface functional groups were proved to not only hinder the agglomeration of nanosheets but also further donate active sites and improve storage capacity. These advantageous features achieved by designing such a stacked structure with functionalized carbon modification provide a promising strategy for the preparation of high-performance anode materials and other 2D functional materials.

Co3Sn2/SnO2 nanocomposite loaded on Cu foam as high-performance three-dimensional anode for lithium-ion batteries

It is a challenge to commercialize tin dioxide-based anodes for lithium-ion batteries due to their low rate capability and poor cycling performance of the electrodes.

Plasma-treated Ti3+-doped sodium titanate nanosheet arrays on titanium foil as a lithiophilic current collector for a stable lithium metal anode

Ar/H₂ plasma-treated Ti³⁺-doped sodium titanate nanosheet arrays on titanium foil can induce a uniform lithium deposition.

Homogeneous growth of TiO2-based nanotubes on nitrogen-doped reduced graphene oxide and its enhanced performance as a Li-ion battery anode

The pursuit of a promising replacement candidate for graphite as a Li-ion battery anode, which can satisfy both engineering criteria and market needs has been the target of researchers for more than two decades. In this work, we have investigated the synergistic effect of nitrogen-doped reduced graphene oxide (NrGO) and nanotubular TiO₂ to achieve high rate capabilities with high discharge capacities through a simple, one-step and scalable method. First, nanotubes of hydrogen titanate were hydrothermally grown on the surface of NrGO sheets, and then converted to a mixed phase of TiO₂-B and anatase (TB) by thermal annealing. Specific surface area, thermal gravimetric, structural and morphological characterizations were performed on the synthesized product. Electrochemical properties were investigated by cyclic voltammetry and cyclic charge/discharge tests. The prepared anode showed high discharge capacity of 150 mAh g^-1 at 1 C current rate after 50 cycles. The promising capacity of synthesized NrGO-TB was attributed to the unique and novel microstructure of NrGO-TB in which long nanotubes of TiO₂ have been grown on the surface of NrGO sheets. Such architecture synergistically reduces the solid-state diffusion distance of Li⁺ and increases the electronic conductivity of the anode.

Size- and Density-Controllable Fabrication of the Platinum Nanoparticle/ITO Electrode by Pulse Potential Electrodeposition for Ammonia Oxidation

Pulse potential electrodeposition was successfully utilized to electrochemically fabricate platinum (Pt) nanoparticles on indium tin oxide (ITO) conductive glass substrates for catalysis toward ammonia electro-oxidation. The effect of deposition parameters (lower potential E_l, lower potential duration t_l, and upper potential duration t_u) on the size and number density of Pt nanoparticles was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrocatalytic activity of the Pt nanoparticle/ITO electrode for ammonia oxidation was characterized by the cyclic voltammetry (CV) method. The results showed that lower E_l and longer t_l accelerate the formation of Pt nuclei while longer t_u favors the growth of grain size to some extent, as E_l mainly tunes electrochemical overpotential while t_l and t_u affect the activation and mass transfer process. By the tuning of the deposition parameters, Pt nanoparticle/ITO electrodes with a polycrystalline nature and 5 nm-scale primary particles, could be easily modified in Pt particle size and number density. Furthermore, the Pt nanoparticle/ITO electrode shows high mass specific catalytic activity (MA) toward ammonia oxidation (1.65 mC μg^-1), much higher than that of the commercial Pt/C electrode (0.32 mC μg^-1). Additionally, the high catalytic performance results not only from the nanosize effect of Pt nanoparticles, but also from the special morphology formed during the electrodeposition process.

An internal magnetic field strategy to reuse pulverized active materials for high performance: a magnetic three-dimensional ordered macroporous TiO2/CoPt/α-Fe2O3 nanocomposite anode

An internally magnetic field was established by CoPt for attracting pulverized ferromagnetic α-Fe₂O₃. Combining with the unique porous structure for accommodating large volume change, the TiO₂/CoPt/α-Fe₂O₃ (3DOMTCF) anode demonstrated high reversible capacity and extremely promising cyclic stability.