Jiaguo Yu - Semiconductor Solar Photocatalysts: Fundamentals and Applications

1. Chapter 1
2. Chapter 5

1. Chapter 1
2. Chapter 2
3. Chapter 3
4. Chapter 4
5. Chapter 5
6. Chapter 6

Edited by

Jiaguo Yu, Xin Li, and Jingxiang Low

Xin Li1 and Jiaguo Yu2

1Institute of Biomass Engineering, South China Agricultural University, 483 Wushan Road, Tianhe District, Guangzhou, 510642, P. R. China

2China University of Geosciences, Laboratory of Solar Fuel, Faculty of Materials Science and Chemistry, 388 Lumo Road, Wuhan, 430074, P. R. China

Solar energy semiconductor photocatalysis has long been considered to be the best solution to various kinds of energy and environmental problems. During the past decades, the solar energy semiconductor photocatalysis has attracted more and more attention. Based on b).

So far, hundreds of solar energy semiconductor photocatalysts have been exploited and applied in the different photocatalytic fields, including the plasmonic metals, metal oxides/hydroxides, sulfides, nitrides, metalfree polymers, organic semiconductors, and their composites. Although some reviews covered the progresses of these kinds of semiconductors, there are few books systematically summarizing the advances in these semiconductors. Therefore, it is timely to provide a comprehensive book to thoroughly elaborate the exploitation and application of typical kinds of solar energy semiconductors in the different photocatalytic fields. We believe that this book can help the researchers easily grasp the recent achievements for various kinds of semiconductors and inspire their new ideas in developing new solar energy semiconductors for efficient photocatalysis.

Due to its green and renewable advantages, photocatalysis has been one of the most active directions in the field of chemistry in recent years.

The number of publications on photocatalysis found by searching with the following keywords: (a) topic: (photoca*), (b) topic 1: (photoca*), and topic 2: (hydrogen or H2 or H2), (carbon dioxide or CO2 or CO2), or (degradat*).

Source: Science Core Collection 26 November 2019.

Semiconductor photocatalysis can be traced back to 1839. Becquerel first discovered the photoelectric phenomenon, although he did not explain it theoretically.

In 1955, Brattain and Garrett gave a reasonable explanation for the photoelectric phenomena, marking the birth of photoelectrochemistry.

Especially in 1972, Fujishima and Honda first found that ntype semiconductor rutile TiO2 single crystal electrode could achieve the photocatalytic decomposition of H2O to O2 under the ultraviolet ( UV ) light (with 380nm wavelength), while on the counter electrode Pt simultaneously produces H2 . This great discovery has caused a sensation all over the world, which revealed the possibility of using solar energy to decompose water for hydrogen production or to convert solar energy directly into chemical energy thus opening up a new era of semiconductor photocatalysis research and attracting worldwide attention. Because of its farreaching significance in the development of new energy and the protection of ecological environment, heterogeneous semiconductor photocatalysis has become a hot spot, attracting the extensive attention of researchers in many fields, such as chemistry, physics, and materials.

In the middle and late 1970s, Carey et al. utilized the TiO2 suspension to degrade polychlorinated biphenyls and cyanides, respectively, under UV irradiation, which set off a research upsurge of environmental photocatalysis technology with the main purpose of decomposing environmental pollutants.

Schrauzer also confirmed that TiO2 with rutile and anatase mixed crystal phases can realize the photocatalytic decomposition of chemisorbed water into H2 and O2 with a 2 : 1 stoichiometric ratio .

At the same time, Bard and his coworkers have guided and promoted the development of photoelectrochemistry. They first extended the theory of photoelectrochemistry (microelectrode model) to the photocatalysis of semiconductor particles, advancing the semiconductor photocatalysis technology greatly in theory. They not only used electron paramagnetic resonance ( EPR ) spectroscopy to characterize the free radicals such as hydroxyl (OH) and hydroperoxyl (OOH) radicals in the processes of photocatalytic oxidation and photocatalytic reduction of O2 .

In 1978, Halmann found that CO2 dissolved in the electrolyte could be reduced to formic acid (HCOOH), formaldehyde, and methanol (CH3OH) by using pGaP single crystal, carbon rod, and K2HPO4KH2PO4 buffer solution as cathode, anode, and electrolyte, respectively, under the necessary applied bias voltage .

In the same year, Somorjai first used SrTiO3 to achieve the photocatalytic conversion of CO2 and water vapor to CH4 .