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Sodium-ion batteries (SIBs) are among the most cost-effective and environmentally benign electrical energy storage devices required to match the needs of commercialized stationary and automotive applications. Because of its excellent chemical characteristics, infinite abundance, and low cost, the SIB is an excellent technology for grid energy storage compared with others. When used as anodes, titanium compounds based on the Ti4+/Ti3+ redox couple have a potential of typically 0.5–1.0 V, which is far from the potential of dangerous sodium plating (0.0–0.1 V). This ensures the operational safety of large-scale SIBs. Low lattice strain, usually associated with Ti-based materials, is also helpful for the longevity of the cycling of SIBs. Numerous Ti-based anode materials are being developed for use in SIBs. In particular, due to adequate electrode–electrolyte interaction and rapid charge transportation, hierarchical porous (HP) Ti-based anode materials were reported as having high specific capacity, current density, and cycling stability. HPTi-based anode materials for SIBs have the potential to be used in automobiles and portable, flexible, and wearable electronic devices. This review addresses recent developments in HPTiO2-based SIBs and their preparation, properties, performance, and challenges.

Highly durable and antimicrobial tantalum nitride/copper (TaN/Cu) nanocomposite coatings were deposited on D-9 stainless steel substrates by pulsed magnetron sputtering. The Cu content in the coating was varied in the range of 1.42–35.42 atomic % (at.%). The coatings were characterized by electron probe microanalyzer, X-ray diffraction, scanning electron microscope and atomic force microscope. The antibacterial properties of the TaN/Cu coatings against gram-negative Pseudomonas aeruginosa were evaluated using a cell culture test. The peak hardness and Young’s modulus of TaN/Cu with 10.46 at.% Cu were 24 and 295 GPa, respectively, which amounted to 15 and 41.67% higher than Cu-free TaN. Among all, TaN/Cu with 10.46 at.% exhibited the lowest friction coefficient. The TaN/Cu coatings exhibited significantly higher antibacterial activity than Cu-free TaN against Pseudomonas aeruginosa. On TaN, the bacterial count was about 4 × 106 CFU, whereas it was dropped to 1.2 × 102 CFU in case of TaN/Cu with 10.46 at.% Cu. The bacterial count was decreased from 9 to 6 when the Cu content increased from 25.54 to 30.04 at.%. Live bacterial cells were observed in the SEM images of TaN, and dead cells were found on TaN/Cu. Overall, TaN/Cu with 10.46 at.% Cu was found to be a potential coating composition in terms of higher antimicrobial activity and mechanical durability.

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Plant extracts have been utilized as an ecofriendly natural reducing agent for the synthesis of nanomaterials, including metal oxides. Prickly pear (opuntia) fruit extract (PPE) was used as a reducing agent for the sol–gel synthesis of titanium dioxide nanoparticles (TiO2 NPs) and as a sensitizer for the TiO2 NPs photoanode used in dye-sensitized solar cells (DSSCs). Ultraviolet-visible and infrared spectra, X-ray diffraction patterns, and scanning electron microscopic images were confirmed in the formation of semiconducting TiO2 NPs with the predominate size of ~300 nm. The use of PPE rendered discrete TiO2 NPs, whereas the typical synthesis without PPE resulted TiO2 aggregates. TiO2 NPs had a tetragonal crystalline structure, and their grain size was varied with respect to the concentration of PPE. The size of TiO2 crystallites was found to be 20, 19, 15, and 10 nm when the volume percentage of PPE was 0.2, 0.4, 0.6, and 0.8%, respectively. TiO2 NPs obtained using PPE were coated on indium-doped tin oxide substrates and sensitized with natural dye made up of PPE and synthetic dyes, namely rose Bengal (RB) and eosin yellow (EY). The photoanode fabricated with dye-sensitized TiO2 NPs was subjected to current–voltage response studies. The maximum power-conversion efficiency, 1.4%, was recorded for photoanodes sensitized with PPE dye, which is considerably higher than that for RB (1.16%) or EY (0.8%). Overall, the above findings proved that PPE can be used as a potential reducing/capping agent and TiO2 sensitizer for DSSC applications.