PHD
  1. Inorganic chemistry  1.1. Coordination chemistry  1.1.1. Ligand field theory  1.1.2. Crystal field theory  1.1.3. Molecular Orbital Theory for Coordination Compounds  1.1.4. Stability of Coordination Compounds  1.1.5. Electronic spectra of coordination compounds  1.1.6. Isomerism in Coordination Compounds  1.1.7. Kinetics and mechanism of coordination reactions  1.2. Organometallic Chemistry  1.2.1. Metal Carbonyls  1.2.2. Metal alkyl and aryl  1.2.3. Fischer and Schrock carbonaceans  1.2.4. Oxidative Addition and Reductive Elimination  1.2.5. Metal Hydrides  1.2.6. Catalysis by organometallic compounds  1.2.7. Metallocenes and Sandwich Complexes  1.2.8. CH activation  1.3. Solid state chemistry  1.3.1. Crystal structures and lattices  1.3.2. Band theory and electrical properties  1.3.3. Defects in the crystal  1.3.4. Synthesis of solid state materials  1.3.5. Magnetic and optical properties of solids  1.3.6. Superconductivity  1.3.7. Solid state ionics  1.4. Bio-inorganic chemistry  1.4.1. Metalloproteins and enzymes  1.4.2. Metal ion transport and storage  1.4.3. The role of metals in medicine  1.4.4. Bioinspired catalysis  1.4.5. Metal–DNA interactions  1.4.6. Metal Complexes in Medical Science  1.5. Lanthanides and Actinides  1.5.1. Electronic configuration and oxidation states in lanthanides and actinides  1.5.2. Spectral and Magnetic Properties in Lanthanides and Actinides  1.5.3. Separation and Extraction of Lanthanides and Actinides  1.5.4. Coordination chemistry of f-block elements  1.6. Main Group Chemistry  1.6.1. Chemistry of boron compounds  1.6.2. Chemistry of Silicon and Germanium Compounds  1.6.3. Chemistry of Phosphorus and Sulfur Compounds  1.6.4. Organosilicon chemistry  1.6.5. Noble Gas Chemistry
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition and substitution reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic Reactions  2.1.7. Photochemical reactions  2.2. Stereoscopic  2.2.1. Chirality and optical activity  2.2.2. Structural analysis  2.2.3. Stereoelectronic effects  2.2.4. Asymmetric synthesis  2.2.5. Dynamic Stereochemistry  2.3. Organometallic Chemistry in Organic Synthesis  2.3.1. Organolithium and organomagnesium reagents  2.3.2. Transition metal catalyzed coupling reactions  2.3.3. Palladium-catalyzed reactions  2.3.4. Olefin Metathesis  2.3.5. Gold and silver catalysis  2.4. Natural products chemistry  2.4.1. Alkaloids and terpenoids  2.4.2. Steroids and Flavonoids  2.4.3. Total synthesis of natural products  2.4.4. Biosynthesis of natural products  2.5. Supramolecular Chemistry  2.5.1. Host-Guest Chemistry  2.5.2. Self-assembly and molecular recognition  2.5.3. Supramolecular Catalysis  2.5.4. Molecular Machines
  3. Physical Chemistry  3.1. Thermodynamics  3.1.1. Laws of Thermodynamics  3.1.2. Chemical Potential and Equilibrium  3.1.3. Statistical thermodynamics  3.1.4. Non-equilibrium thermodynamics  3.2. Quantum Chemistry  3.2.1. Schrödinger equation and its applications  3.2.2. Molecular orbital theory  3.2.3. Density functional theory  3.2.4. Post-Hartree–Fock methods  3.3. Chemical kinetics  3.3.1. Reaction rate theory  3.3.2. Mechanism and rate laws  3.3.3. Catalysis and enzyme kinetics  3.3.4. Reaction dynamics  3.4. Spectroscopy and molecular structure  3.4.1. Infrared Spectroscopy  3.4.2. UV-visible spectroscopy  3.4.3. Nuclear Magnetic Resonance Spectroscopy  3.4.4. Mass Spectrometry  3.4.5. Raman Spectroscopy  3.5. Surface and Colloid Chemistry  3.5.1. Absorption and Catalysis  3.5.2. Surfactants and micelles  3.5.3. Colloidal Stability  3.5.4. Nanomaterials and Interfaces
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.1.4. Ion Chromatography  4.2. Electroanalytical techniques  4.2.1. Voltammetry and Polarography  4.2.2. Conductometry and potentiometry  4.2.3. Colometry  4.3. Spectroscopic Methods  4.3.1. Atomic absorption spectroscopy  4.3.2. Fluorescence Spectroscopy  4.3.3. X-ray diffraction  4.3.4. Electron paramagnetic resonance spectroscopy  4.4. Chemometrics  4.4.1. Data processing and statistical methods  4.4.2. Multidisciplinary analysis  4.4.3. Machine Learning in Analytical Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.2. Quantum chemistry methods  5.3. Computational drug design  5.4. Machine Learning in Chemistry  5.5. Ab initio molecular dynamics
  6. Biophysics and Medicinal Chemistry  6.1. Drug discovery and design  6.2. Enzyme kinetics and inhibition  6.3. Chemical biology approach  6.4. Protein-ligand interactions  6.5. Bioorthogonal chemistry
  7. Materials chemistry  7.1. Polymer chemistry  7.1.1. Polymerization mechanism  7.1.2. Functional Polymers  7.1.3. Biodegradable Polymer  7.1.4. Conducting and semiconducting polymers  7.2. Nano Chemistry  7.2.1. Nanoparticles and nanostructures  7.2.2. Carbon-based nanomaterials  7.2.3. Quantum dots  7.3. Energy and Environmental Chemistry  7.3.1. Battery and Fuel Cell Chemistry  7.3.2. Green chemistry and sustainable materials  7.3.3. Photocatalysis

PHD → Materials chemistry → Energy and Environmental Chemistry ↓


Photocatalysis


Photocatalysis is an exciting area of chemistry where light energy is used to drive chemical reactions. This process holds a significant promise for energy and environmental applications. It revolves around using light to excite a catalyst, causing transformations that can be challenging to achieve under normal conditions. Let's delve deeper into this fascinating world of photocatalysis.

Fundamentals of photocatalysis

Photocatalysis involves a substance called a photocatalyst, which aids chemical reactions when it absorbs light. Unlike a normal chemical reaction where the reagents are consumed directly, the photocatalyst remains unchanged after the reaction. This property offers a sustainable approach to facilitating reactions, reducing energy consumption and waste.

How does photocatalysis work?

This process begins with the absorption of photons by the photocatalyst. When light strikes the surface of the photocatalyst, electrons in the material are excited from the valence band to the conduction band, creating electron-hole pairs. These pairs can then participate in redox reactions, leading to otherwise impossible chemical transformations.

The role of the photocatalyst

A photocatalyst is crucial to this process. Materials such as titanium dioxide (TiO2), zinc oxide (ZnO), and cadmium sulfide (CdS) are commonly used for their efficient light absorption properties and reactivity. These materials have specific structures that facilitate electron movement, which is important for creating electron-hole pairs.

Electron excitation in titanium dioxide

In TiO2, the excitation of electrons can be illustrated as follows:

    VB : valence band ⟶ excitation ⟶ CB : conduction band
TiO2 Photon

Applications in energy

Photocatalysis is the cornerstone for a variety of energy-related applications. Its ability to convert solar energy into chemical energy is of significant interest for sustainable energy technologies.

Solar water splitting

Photocatalysis plays a key role in solar water splitting, an innovative way to generate hydrogen from water using sunlight. In this process, light-induced electron-hole pairs in the photocatalyst drive the electrolysis of water:

2H2O ⟶ 2H2 + O2

This process has enormous potential, providing a clean and renewable means for producing hydrogen, a valuable energy carrier.

water H2O Photocatalysis H2 O2

Photocatalytic fuel cells

Photocatalytic fuel cells combine conventional fuel cells with photocatalysis, increasing electricity production. Light provides energy to photocatalytic materials, which break down organic fuels while also producing electricity.

Such systems are essential for the development of portable and high-efficiency energy devices.

Applications in environmental chemistry

Photocatalysts have had a profound impact in environmental chemistry for pollution control and purification processes.

Water and air purification

Photocatalysts are used extensively to decompose harmful pollutants in water and air. Titanium dioxide (TiO2)-based systems are particularly popular, capable of breaking down a variety of organic and inorganic components upon exposure to light.

Decomposition of pollutants

The general equation representing photocatalytic disintegration is:

    Pollutant + TiO2 / light ⟶ CO2 + H2O + harmless byproduct

Destruction of microorganisms

In addition to breaking down chemical pollutants, photocatalysis is also effective against microorganisms such as bacteria and viruses, providing a dual-action purification technology.

Challenges and future prospects

Despite its potential, photocatalysis faces several hurdles. The efficiency of light absorption, rapid recombination of electron-hole pairs, and the cost of materials are some of the areas that require progress.

Continuing research aims to develop better photocatalysts with improved efficiency and cost-effectiveness. Nanostructured materials and hybrid systems providing better light absorption and activity are promising directions.

Conclusion

Photocatalysis is a leading field in chemistry, presenting enormous potential in addressing global energy needs and environmental challenges. Its ability to drive chemical transformations with light opens new avenues for sustainable and green chemistry practices.


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Photocatalysis

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