Photocatalytic Organic Transformations with Titanium Dioxide

Titanium dioxide (TiO₂) serves as a benchmark photocatalyst in the pursuit of sustainable organic synthesis, exploiting its semiconductor properties to absorb light and generate charge carriers. Upon irradiation, electrons are promoted from the valence band to the conduction band, leaving photogenerated holes that act as powerful oxidants. These charge carriers mediate a wide variety of transformations, including selective oxidations, reductive hydrogenations, C–C and C–heteroatom couplings, and C–H bond activations. Surface modifications—such as metal doping, dye sensitisation and hybridisation with carbonaceous supports—extend light absorption into the visible region and suppress electron–hole recombination, thereby improving catalytic efficiency. Practical applications encompass green oxidations of sulfides, photoreductive conversions of nitroaromatics, photocatalytic transfer hydrogenations using alcohols or amines as hydrogen sources, and direct C–N bond constructions under ambient conditions. These methodologies operate under mild reaction parameters, minimise waste and demonstrate high selectivity, positioning TiO₂ photocatalysis as a cornerstone technology for eco-friendly chemical manufacturing and pharmaceutical synthesis.

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Photocatalytic Organic Transformations with Titanium Dioxide publication trend

The graph below shows the total number of articles in photocatalytic organic transformations with titanium dioxide across all publications each year (not limited to Nature Index journals).

Technical terms

Photocatalysis: A process in which a catalyst absorbs light to generate reactive species that drive chemical transformations.

Semiconductor: A material whose electronic structure features a band gap between valence and conduction bands, allowing controlled excitation of electrons.

Conduction band: The higher‐energy band in a semiconductor that receives electrons excited by light.

Valence band: The lower‐energy band containing electrons prior to photoexcitation.

Photogenerated hole: The positive charge left in the valence band when an electron is promoted to the conduction band, acting as a potent oxidant.

References

1. Application of metal oxide semiconductors in light-driven organic transformations. Catalysis Science & Technology (2019).
2. TiO2 Photocatalysis for Transfer Hydrogenation. Molecules (2019).
3. Selective Photocatalytic Reduction of Nitrobenzene to Aniline Using TiO2 Embedded in sPS Aerogel. Polymers (2023).