TiO ₂ ‐Based Heterogeneous Catalysis for Photocatalytic Hydrogen Generation and Photodegradation

Abstract

Globalization, industrialization, and manufacturing have expanded at an alarming rate over past decades. This has caused a rapid depletion of natural energy sources (such as oil and gas) and the production of tones of wastes polluting the environment, which in turn has imposed negative impact on human health. A promising way to tackle the energy crisis and environmental issues is to substitute traditional fossil fuels with clean and sustainable sources of energy. Among them, solar energy is an inexhaustible and the most environment‐friendly resource, which can be effectively absorbed and utilized via a photocatalysis process for hydrogen production from water splitting and degradation of organic pollutants. Titanium dioxide (TiO 2 ) is one of the most extensively studied photocatalytic materials, by virtue of its compatible band‐edge position, physiochemical stability, nontoxicity and low cost. However, its photoactivity is remarkably restricted due to the inefficient light absorption only in the UV region of the solar spectrum, as well as easy recombination of photogenerated electrons/holes. To mitigate these limitations, synergistic combination of electronic and structural strategies has been developed in recent years. In this chapter, we have highlighted TiO 2 ‐based photocatalysts with well‐defined electronic structure control and structural design that contribute to significant improvements in vital processes and attributes, such as light absorption in the visible region, charge‐carrier dynamics, high surface area, and enhanced light harvesting. Electronic structure engineering, namely doping and heterostructuring, plays a critical role in improving the kinetics of the charge carriers, that is, the separation of electrons and holes pairs, and the extension of light absorption to visible light region, thereby enhancing the photoefficiency of TiO 2 . The structural design of TiO 2 involves various dimensions and morphologies, which not only augments the specific surface area, but also provides suitable platforms to incorporate other materials for maximizing the photocatalytic efficiency. Furthermore, fundamental understanding of the kinetics and dynamics of photoreactivity and other physicochemical properties is covered. The goal is to provide a comprehensive background toward rational engineering of semiconducting photocatalysts and also a guide for future structural design of nanoscale catalysts for solar‐to‐fuel conversion purposes in pursuit of an exciting future of clean and renewable fuel and environmental remediation.

Investigation on visible light-driven antimicrobial and mechanistic activity of GO/TiO2(V–N) nanocomposite against wound pathogens

“…Consequently, protein leakage increased, where the high protein leakage confirms the cell wall damage. 73…”

“…The GO/TiO 2 (V-N) NC interacted and damaged the bacterial cell wall, which destabilised the membrane permeability, ultimately resulting in the loss of membrane integrity. Consequently, protein leakage increased, where the high protein leakage confirms the cell wall damage 73.…”

A Convenient In Situ Preparation of Cu2ZnSnS4–Anatase Hybrid Nanocomposite for Photocatalysis/Photoelectrochemical Water-Splitting Hydrogen Production

“…Its suitable band gap allows for excitation by ultraviolet light, while its high catalytic activity and photo-generated charge carriers with a strong redox capacity have garnered significant scientific interest. This surge in attention traces back to the groundbreaking work by Fujishima and Honda, who first reported on photoelectrochemical (PEC) water splitting using TiO 2 electrodes [ 4 , 7 , 8 , 9 , 10 , 11 ]. However, the practical application of TiO 2 is somewhat constrained by its relatively large band gap (3.0~3.2 eV) and the rapid recombination rate of light-generated electron–hole pairs, limiting its efficient utilization of visible light [ 7 , 12 ].…”

CeO2/TiO2 Heterojunction Nanotube Arrays for Highly Efficient Visible-Light Photoelectrochemical Water Splitting

“…However, TiO 2 has a wide band gap (∼3.2 eV for anatase) and only responds to UV light, which accounts for 4% of the solar spectrum, severely limiting its practical application. 4,5 Furthermore, a short hole diffusion path (less than 10 ns) in TiO 2 inhibits the charge transfer, resulting in a quick recombination rate. 6,7 Various strategies, including surface sensitization, 8,9 doping, 10−12 and constructing heterostructure, 13−16 have been explored to improve the PEC performance of TiO 2 by extending the spectral absorption range and promoting the charge separation efficiency.…”

“…Among numerous semiconductor materials, TiO 2 has been widely studied due to its low cost, nontoxicity, good chemical stability, and abundance. , TiO 2 has a suitable band gap to drive the splitting of water into H 2 and O 2 . However, TiO 2 has a wide band gap (∼3.2 eV for anatase) and only responds to UV light, which accounts for 4% of the solar spectrum, severely limiting its practical application. , Furthermore, a short hole diffusion path (less than 10 ns) in TiO 2 inhibits the charge transfer, resulting in a quick recombination rate. , Various strategies, including surface sensitization, , doping, − and constructing heterostructure, − have been explored to improve the PEC performance of TiO 2 by extending the spectral absorption range and promoting the charge separation efficiency. The construction of TiO 2 nanotube (TNT) arrays can vastly enhance the transfer of charge carriers and prolong the recombination time of electron/hole pairs due to their unique tubular structure. ,, However, the PEC performances of TNT arrays should be further improved to achieve high solar-to-H 2 efficiency for commercial applications.…”