Increasing local pH due to oxygen reduction induced self-discharge is the main mechanism of material dissolution and capacity fade of NaTi ₂ (PO ₄ ) ₃ electrodes in aqueous media. This problem can be strongly mitigated by ALD of a protective Al ₂ O ₃ layer.

The high efficiency of perovskite solar cells strongly depends on the quality of perovskite films and carrier extraction layers. Here, we present the results of an investigation of the photoelectric properties of solar cells based on perovskite films grown on compact and mesoporous titanium dioxide layers. Kinetics of charge carrier transport and their extraction in triple-cation perovskite solar cells were studied by using transient photovoltage and time-resolved photoluminescence decay measurements. X-ray diffraction analysis revealed that the crystallinity of the perovskite films grown on mesoporous titanium dioxide is better compared to the films grown on compact TiO₂. Mesoporous structured perovskite solar cells are found to have higher power conversion efficiency mainly due to enlarged perovskite/mesoporous -TiO₂ interfacial area and better crystallinity of their perovskite films.

Ožiūnas R, et al. J Adv Prosthodont. 2023 Feb;15(1):33-43. https://doi.org/10.4047/jap.2023.15.1.33

The application of atomic layer deposition on active material particles or as conformal layers directly on electrodes is an effective and viable approach for protecting the battery materials from degradation. Al₂O₃, TiO₂, and HfO₂ coatings are applied on NaTi₂(PO₄)₃, which is among the most studied negative electrode materials for aqueous Na-ion batteries. The coated electrodes are characterized in terms of electrochemical kinetics, charge capacity retention, and electrochemical impedance spectra. Al₂O₃, a widely used protective coating in non-aqueous batteries, is shown to be insufficient to suppress parasitic processes and is eventually dissolved by reaction with hydroxide during extended cycling in aqueous Na₂SO₄. However, this process provides a local buffering effect making the protective action of this coating mainly of chemical nature. TiO₂ is found to be very resistant to increase in pH and remains almost intact during electrochemical cycling. However, we provide strong evidence that TiO₂ itself is electrochemically active in aqueous electrolytes at negative potentials. The protonation of TiO₂ leads to an additional increase in local pH which is detrimental to NaTi₂(PO₄)₃ and results in even faster capacity loss than in uncoated electrodes. Only HfO₂ is found to be sufficiently stable and electrochemically inert ALD coating for negative NaTi₂(PO₄)₃ electrodes operating in aqueous electrolytes.

Niobium-doped titanium dioxide (Ti_1−xNb_xO₂) films were grown on p-type Si substrates at low temperature (170 °C) using an atomic layer deposition technique. The as-deposited films were amorphous and showed low electrical conductivity. The films became electrically well-conducting and crystallized into the an anatase structure upon reductive post-deposition annealing at 600 °C in an H₂ atmosphere for 30 min. It was shown that the Ti_0.72Nb₀.₂₈O₂/p⁺-Si heterojunction fabricated on low resistivity silicon (10⁻³ Ω cm) had linear current–voltage characteristic with a specific contact resistivity as low as 23 mΩ·cm². As the resistance dependence on temperature revealed, the current across the Ti_0.72Nb_0.28O₂/p⁺-Si heterojunction was mainly determined by the band-to-band charge carrier tunneling through the junction.