A Short Review on the Effects of Doping in TiO2: A Potential Nano-photocatalyst for Hydrogen Production by Artificial Photosynthesis Process

Photocatalysis is a natural process used by plants. In this process, light energy is converted into chemical energy through biochemical conversion. During the conversion, water, a vital component of the process, splits into oxygen and hydrogen. This phenomenon attracted researchers the most, and a new era of artificial photosynthesis started. Artificial photosynthesis basically mimics the water-splitting system of the natural one and produces hydrogen. Hydrogen is a green source of energy which is renewable and is thought to be the potential replacement of conventional energy sources. The world is going through an energy crisis where the storage of fossil fuels is running out, and the hazardous effects of their combustion are alarming. However, the production of hydrogen is one of the main challenges of this fuel. Titanium dioxide (TiO2) nanoparticle is a well-established photocatalyst used in hydrogen production by artificial photosynthesis process traditionally. This nanoparticle captures photons with an energy higher than the band gap. It creates the pairs of electrons and holes which are migrated within the semiconductor from the valence band to the conduction band and react with water to release hydrogen. Doping in TiO2 nano-photocatalyst has a significant effect on hydrogen production. Those effects are discussed in this review article.