Acta Phys. -Chim. Sin. ›› 2022, Vol. 38 ›› Issue (11): 2201021.

Special Issue: Special Issue of Emerging Scientists

• REVIEW •

Advances in Nanostructured Silicon Carbide Photocatalysts

Kelin He1, Rongchen Shen1, Lei Hao1, Youji Li2, Peng Zhang3, Jizhou Jiang4, Xin Li1,*()

1. 1 Institute of Biomass Engineering, Key Laboratory of Energy Plants Resource and Utilization, Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou 510642, China
2 College of Chemistry and Chemical Engineering, Jishou University, Jishou 416000, Hunan Province, China
3 State Center for International Cooperation on Designer Low-Carbon & Environmental Materials (CDLCEM), School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China
4 School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan 430205, China
• Received:2022-01-13 Accepted:2022-03-17 Published:2022-03-24
• Contact: Xin Li E-mail:xinli@scau.edu.cn; xinliscau@126.com
• About author:Xin Li, Email: xinli@scau.edu.cn; xinliscau@126.com
• Supported by:
the National Natural Science Foundation of China(21975084);the National Natural Science Foundation of China(51672089)

Abstract:

Industrialization undoubtedly boosts economic development and improves the standard of living; however, it also leads to some serious problems, including the energy crisis, environmental pollution, and global warming. These problems are associated with or caused by the high carbon dioxide (CO2) and sulfur dioxide (SO2) emissions from the burning of fossil fuels such as coal, oil, and gas. Photocatalysis is considered one of the most promising technologies for eliminating these problems because of the possibility of converting CO2 into hydrocarbon fuels and other valuable chemicals using solar energy, hydrogen (H2) production from water (H2O) electrolysis, and degradation of pollutants. Among the various photocatalysts, silicon carbide (SiC) has great potential in the fields of photocatalysis, photoelectrocatalysis, and electrocatalysis because of its good electrical properties and photoelectrochemistry. This review is divided into six sections: introduction, fundamentals of nanostructured SiC, synthesis methods for obtaining nanostructured SiC photocatalysts, strategies for improving the activity of nanostructured SiC photocatalysts, applications of nanostructured SiC photocatalysts, and conclusions and prospects. The fundamentals of nanostructured SiC include its physicochemical characteristics. It possesses a range of unique physical properties, such as extreme hardness, high mechanical stability at high temperatures, a low thermal expansion coefficient, wide bandgap, and superior thermal conductivity. It also possesses exceptional chemical characteristics, such as high oxidation and corrosion resistance. The synthesis methods for obtaining nanostructured SiC have been systematically summarized as follows: Template growth, sol-gel, organic precursor pyrolysis, solvothermal synthesis, arc discharge, carbon thermal reduction, and electrospinning. These synthesis methods require high temperatures, and the reaction mechanism involves SiC formation via the reaction between carbon and silicon oxide. In the section of the review involving the strategies for improving the activity of nanostructured SiC photocatalysts, seven strategies are discussed, viz., element doping, construction of Z-scheme (or S-scheme) systems, supported co-catalysts, visible photosensitization, construction of semiconductor heterojunctions, supported carbon materials, and construction of nanostructures. All of these strategies, except element doping and visible photosensitization, concentrate on enhancing the separation of holes and electrons, while suppressing their recombination, thus improving the photocatalytic performance of the nanostructured SiC photocatalysts. Regarding the element doping and visible photosensitization strategies, element doping can narrow the bandgap of SiC, which generates more holes and electrons to improve photocatalytic activity. On the other hand, the principle of visible photosensitization is that photo-induced electrons move from photosensitizers to the conduction band of SiC to participate in the reaction, thus enhancing the photocatalytic performance. In the section on the applications of nanostructured SiC, photocatalytic H2 production, pollutant degradation, CO2 reduction, photoelectrocatalytic, and electrocatalytic applications will be discussed. The mechanism of a photocatalytic reaction requires the SiC photocatalyst to produce photo-induced electrons and holes during irradiation, which participate in the photocatalytic reaction. For example, photo-induced electrons can transform protons into H2, as well as CO2 into methane, methanol, or formic acid. Furthermore, photo-induced holes can convert organic waste into H2O and CO2. For photoelectrocatalytic and electrocatalytic applications, SiC is used as a catalyst under high temperatures and highly acidic or basic environments because of its remarkable physicochemical characteristics, including low thermal expansion, superior thermal conductivity, and high oxidation and corrosion resistance. The last section of the review will reveal the major obstacles impeding the industrial application of nanostructured SiC photocatalysts, such as insufficient visible absorption, slow reaction kinetics, and hard fabrication, as well as provide some ideas on how to overcome these obstacles.

MSC2000:

• O643