Hierarchical graphene@TiO2 sponges for sodium-ion storage with high areal capacity and robust stability

Construction of Binary RGO/TiO2 Fibrous Membranes with Enhanced Mechanical Properties for E. coli Inactivation

For environmental remediation, it is significant to design membranes with good mechanical properties and excellent photocatalytic activity. In this work, RGO/TiO2 membranes with heterogeneous structures and good photocatalytic efficiency were synthesized using the method of electrospinning combined with a thermal treatment process. In the binary nanocomposites, RGO was tightly adhered to TiO2 fibers and by simply adjusting the loading of RGO, the strength and modulus of the fibrous membranes were improved. Notably, the RGO-permeated TiO2 fibers exhibited 1.41 MPa in tensile strength and 140.02 MPa in Young's modulus, which were 705% and 343% of the original TiO2 fibers, respectively. Benefiting from the enhanced light response and the homogeneous and compact heterogeneous structure, the synthesized RGO/TiO2 membranes displayed good antibacterial performance with a photocatalytic inactivation rate of 6 log against E. coli within 60 min. This study offers a highly efficient alternative to inactivate E. coli for the synthesis of TiO2-based membranes.

Introducing Hybrid Defects of Silicon Doping and Oxygen Vacancies into MOF-Derived TiO2-X @Carbon Nanotablets Toward High-Performance Sodium-Ion Storage

Titanium dioxide (TiO2 ) is a promising anode material for sodium-ion batteries (SIBs), which suffer from the intrinsic sluggish ion transferability and poor conductivity. To overcome these drawbacks, a facile strategy is developed to synergistically engineer the lattice defects (i.e., heteroatom doping and oxygen vacancy generation) and the fine microstructure (i.e., carbon hybridization and porous structure) of TiO2 -based anode, which efficiently enhances the sodium storage performance. Herein, it is successfully realized that the Si-doping into the MIL-125 metal-organic framework structure, which can be easily converted to SiO2 /TiO2-x @C nanotablets by annealing under inert atmosphere. After NaOH etching SiO2 /TiO2-x @C which contains unbonded SiO2 and chemically bonded SiOTi, thus the lattice Si-doped TiO2-x @C (Si-TiO2-x @C) nanotablets with rich Ti3+ /oxygen vacancies and abundant inner pores are developed. When examined as an anode for SIB, the Si-TiO2-x @C exhibits a high sodium storage capacity (285 mAh g-1 at 0.2 A g-1 ), excellent long-term cycling, and high-rate performances (190 mAh g-1 at 2 A g-1 after 2500 cycles with 95.1% capacity retention). Theoretical calculations indicate that the rich Ti3+ /oxygen vacancies and Si-doping synergistically contribute to a narrowed bandgap and lower sodiation barrier, which thus lead to fast electron/ion transfer coefficients and the predominant pseudocapacitive sodium storage behavior.

Metal-organic framework derived vanadium-doped TiO2@carbon nanotablets for high-performance sodium storage

Titanium dioxide (TiO₂) as a potential anode material for sodium-ion batteries (SIBs) suffers from the intrinsic poor electronic conductivity and sluggish ionic diffusivity, thus usually leading to the inferior electrochemical performance. Herein, we demonstrate a facile strategy to enhance the sodium storage performance of TiO₂via vanadium (V) doping, using the pre-synthesized V-doped Ti-based metal-organic framework (MOF, MIL-125) as the precursor, which can be converted into the V-doped TiO₂ with simultaneous carbon hybridization and controlled V-doping amount (denote as V_xTiO₂@C, where × represents the V/Ti molar ratio (R_V/Ti)). V-doping not only affects the morphology of the MIL-125 changing from thick to thin nanotablets, but also greatly enhances the electrochemical performance of the V_xTiO₂@C. When used as an anode for SIBs, the V_0.1TiO₂@C exhibits a much higher reversible capacity of 211 mAh/g than that for the undoped TiO₂@C (only 156 mAh/g) after 150 cycles at 100 mA/g. Even after high-rate long-term cycling, the V_0.1TiO₂@C can still display a capacity of 180 mAh/g with a high capacity retention of 137% at 1000 mA/g after 4500 cycles. Structural/electrochemical measurements reveal that V-doping induces the formation of oxygen vacancies as well as Ti³⁺ species, which efficiently improve the electric conductivity and the ion diffusivity of the electrode. Meanwhile, the thinner V_0.1TiO₂@C nanotablets with porous structure and carbon hybridization could facilitate the ion/electron transfer with shortened diffusion pathways.

Recent Advances in Synthesis and Applications of Carbon-Doped TiO2 Nanomaterials

TiO2 has been widely used as a photocatalyst and an electrode material toward the photodegradation of organic pollutants and electrochemical applications, respectively. However, the properties of TiO2 are not enough up to meet practical needs because of its intrinsic disadvantages such as a wide bandgap and low conductivity. Incorporation of carbon into the TiO2 lattice is a promising tool to overcome these limitations because carbon has metal-like conductivity, high separation efficiency of photogenerated electron/hole pairs, and strong visible-light absorption. This review would describe and discuss a variety of strategies to develop carbon-doped TiO2 with enhanced photoelectrochemical performances in environmental, energy, and catalytic fields. Emphasis is given to highlight current techniques and recent progress in C-doped TiO2-based materials. Meanwhile, how to tackle the challenges we are currently facing is also discussed. This understanding will allow the process to continue to evolve and provide facile and feasible techniques for the design and development of carbon-doped TiO2 materials.