Photocatalytic reaction is one of interaction between light and substance. It is the chemical reaction carried out under the simultaneous action of photons and catalyst. Photocatalytic reaction refers to the electrons and holes that generate after the absorption of photons migrate to the surface of the material and react with the molecules adsorbed on the surface. Activation of organic molecules induced by photons has become a new strategy that is parallel to enzyme catalysis, metal catalysis and organic catalysis. Scientists use computational chemistry to establish the kinetic model of the reaction to obtain necessary information such as the half-reaction rate, electron transfer number and catalytic activity of the reaction, aiming to perform accurate calculation of the photocatalytic reaction. Alfa Chemistry is committed to investigating various photocatalytic reaction mechanism, helping to design novel photocatalysts to achieve effective photocatalytic reactions with high selectivity.
Figure 1. Scheme of the photocatalytic mechanism of the Fe nanoparticles under UV light irradiationathway. (Abdulmohsen Alshehri.; et al. 2017)
Advantages of photocatalytic reaction
- Occur under mild conditions
- Easy to control.
- No heavy metal residues.
- Less waste.
- Cost-effective and environmental friendly.
The photocatalytic reaction process
- The catalyst absorbs photons (the energy of the photon needs to be greater than the band gap value so that the electron can transit from the top of valence band to the bottom of conduction band).
- The electrons that transit to the conduction band are called photogenerated electrons, the holes left in the valence band are called photogenerated holes. And the photogenerated electron-hole pairs migrate within the catalyst.
- Some photogenerated electron-hole pairs recombine inside the catalyst, and some photogenerated electron-hole pairs migrate to the surface of the catalyst.
- The electrons and holes that have migrated to the surface of the catalyst react with the adsorbed substance on the surface of the catalyst, respectively.
Application of Photocatalytic Reaction
- Decomposition of water
Nowadays, the production of clean and renewable energy is a hot spot for current research. Photocatalysis is used to decompose water into H2 and O2, and hydrogen energy is used to replace fossil energy, which is more environmentally friendly and cost-effective.
- Reduction of CO2
Researchers use photocatalytic technology to reduce CO2 to methane, methanol, formic acid and other organic compounds, which has high application value.
- Water pollution control
Compared with the traditional method of water pollution prevention, photocatalytic technology has advantages of environmentally friendly and no second pollution. It can degrade almost all kinds of dyes such as methylene blue, rhodamine, methyl orange, etc., and colorless pollutants, such as phenol, bisphenol A pesticides and antibiotics. In addition, photocatalytic reaction can also be used to reduce some toxic heavy metal ions in water including Cr6+, Pt4+, Au3+ to low ions, thereby weakening their toxicity and reducing damage to the environment.
- Photocatalytic nitrogen fixation
NH3 is an important clean energy source. Nitrogen can be converted into NH3 by solar energy without pollution under normal temperature and pressure. However, the utilization rate of solar energy is relatively low. Photocatalytic nitrogen fixation provides a new strategy to improve the photocatalytic efficiency of N2 fixation.
- Photocatalytic organic synthesis reaction
Although traditional organic synthesis route and production process have been widely used in most chemical fields, they have brought great pollution into environment. At present, researchers have developed the photocatalytic synthesis route using photon as energy to drive chemical reactions under mild reaction conditions.
- Density functional theory (DFT)
Properties and reactivities of photocatalytic process are closely related to the electronic structures of photocatalytic materials, and computational methods based on quantum mechanics are therefore useful in their studying. We apply Kohn-Sham density functional theory (KS-DFT) approach to study the effect of interfacial electron transfer on photocatalytic reaction mechanism and active center of photocatalytic reaction. Moreover, our scientists are capable of performing multiple hybrid functionals including HSE, LSDA, PBEh and HLE, to predict more accurate band gaps and optical properties.
- QM/MM method
QM/MM method allows the application of quantum mechanical methods to large systems by treating a small subsystem by quantum mechanics and the rest of the system by molecular mechanics. Scientists therefore use QM/MM method to study the photocatalytic reaction mechanism and selectivity. At Alfa Chemistry, our teams apply QM/MM method to study the mechanism of photocatalytic reaction of biological systems. In addition, Both bond-tuned link-atom method and the multilink F method are available for dealing with QMMM boundaries, which help to investigate the microscopic mechanism deeply.
- Machine learning (ML)
Data-driven ML techniques have been applied to predict a variety of photocatalytic reaction mechanism. We have designed many training sets of machine learning algorithms and fully considered the electron affinity, ionization capacity, optical band gap, and dispersion of polymers in water. Moreover, we can formulate a practical and general kinetic expression to calculate the mechanisms of photocatalytic reactions.
Advantages of Our Services
1. Better understand the nature of reaction and help to design new photocatalytic reaction catalyst with more functions.
2. The origin of stereoselectivity in asymmetric reactions involving photochemistry is studied by various means of computational chemistry.
Alfa Chemistry provides photocatalytic reaction mechanism calculation services, our teams have rich experience in simulating the photocatalytic reaction and study reaction pathway. If you have any questions, please feel free to contact us.
- Abdulmohsen Alshehri.; et al. Biofabrication of Fe nanoparticles in aqueous extract of Hibiscus sabdariffa with enhanced photocatalytic activities. RSC Advances, 2017, 7: 25149-25159.