Defect Chemistry and Photocatalytic Properties of Titanium Dioxide Thin Films

Titanium dioxide (TiO₂) thin films have long stood at the forefront of photocatalysis research owing to their chemical stability, non-toxicity and strong oxidative potential under ultraviolet illumination. The defect chemistry of these films—principally dominated by oxygen vacancies, interstitial titanium species and surface hydroxyl groups—critically governs their electronic structure, light absorption and charge-carrier dynamics. In anatase and rutile polymorphs, intrinsic and extrinsic defects introduce mid-gap states that extend optical responsiveness into the visible spectrum, while also acting as recombination centres. Precise control of the defect population through deposition parameters (for example, oxygen partial pressure during sputtering), post-deposition annealing and intentional doping enables tuning of the band gap, Fermi level and surface acidity. Such defect engineering has been exploited to improve charge separation and prolong carrier lifetimes, thereby enhancing rates of pollutant degradation, water splitting and selective organic transformations. Mixed-phase films combine the superior charge-transfer characteristics of anatase with the thermodynamic stability of rutile, creating internal heterojunctions that further suppress recombination. Advances in atomic-scale characterisation have revealed how nanoscale defect distributions influence macroscopic photocatalytic performance, opening pathways to designer thin films for energy conversion and environmental remediation on an industrial scale.

Research from Nature Portfolio

Recent studies have employed atomic-resolution electron microscopy to illuminate the mechanisms by which electron-beam radiolysis restructures rutile TiO₂ thin films, revealing a two-step “rolling” model of mobile octahedral building blocks that fill nanometre-wide cracks. This work demonstrates how controlled inelastic scattering can be harnessed to engineer oxygen vacancies and local crystal fields atom-by-atom, thereby tailoring electronic and catalytic properties. Such direct visualisation of defect migration advances our understanding of how nanoscale perturbations can be exploited to design novel photocatalytic architectures with bespoke surface reactivity.

Defect Chemistry and Photocatalytic Properties of Titanium Dioxide Thin Films publication trend

The graph below shows the total number of articles in defect chemistry and photocatalytic properties of titanium dioxide thin films across all publications each year (not limited to Nature Index journals).

Technical terms

Oxygen vacancy: A missing oxygen atom in the TiO₂ lattice that creates donor levels and modifies electronic conductivity.

Anatase: A metastable tetragonal polymorph of TiO₂ noted for high photocatalytic efficiency due to favourable charge-carrier mobility.

Rutile: The thermodynamically stable tetragonal form of TiO₂, valued for its chemical robustness but lower intrinsic photocatalytic rate.

Photocatalysis: A light-driven process in which semiconductor-generated charge carriers induce redox reactions at the surface.

Heterojunction: An interface between two semiconductor phases or materials that facilitates charge separation by internal electric fields.

References

1. Mending cracks atom-by-atom in rutile TiO2 with electron beam radiolysis. Nature Communications (2023).
2. Different architectures of thin film bilayers based on TiO2 and CuO for green hydrogen generation. International Journal of Hydrogen Energy (2025).
3. Phase Quantification of Heterogeneous Surfaces Using DFT-Simulated Valence Band Photoemission Spectra. ACS Applied Materials & Interfaces (2023).
4. Evolution of surface properties of titanium oxide thin films. Applied Surface Science (2023).