A Comprehensive Review on the Boosted Effects of Anion Vacancies in Photocatalytic Solar Water Splitting: Focus on g-C₃N₄ with Carbon and Nitrogen Vacancies

Abstract

As one of the best sustainable approaches for visible-light production of hydrogen (H 2 ) to meet energy demands, semiconductor-based photocatalysis has received broad interest in recent decades. The fundamental restrictions of graphitic carbon nitride (g-C 3 N 4 ) as a promising metal-free photocatalytic semiconductor in water splitting, like insufficient visible-light harvesting and high electron−hole (e/h) pairs recombination, have limited its applications for this goal. In this regard, the optical, charge separation, and surface features of g-C 3 N 4 can be tuned via engineering C/N vacancies, which is reviewed here for water splitting by g-C 3 N 4 . Reports confirm that the enhanced surface features of g-C 3 N 4 resulting from the engineering of C/N vacancies are helpful for water adsorption on its surface, improving the water-splitting kinetics. First in this Review, recent improvements to the structural and optical characteristics of g-C 3 N 4 by introducing C/N vacancies, especially nitrogen vacancies, will be discussed to illustrate its better photocatalytic performance. Then, various strategies for creating and controlling C/N vacancies will be reviewed. The critical roles of C/N vacancies for optimizing photocatalytic performance will also be described, and finally advances in defective photocatalysis water oxidation will be addressed.

Assessment of the Raceway Pond Reactor for Degradation of Methylene Blue Dye in Different Types of Water: A Systematic Kinetics Study under Natural Solar Light

“…Alternatively, the degradation of MB dye using different types of water (deionized, tap, and seawater (DW, TW, and SW)) explores the diverse capabilities of these water sources in treating pollutants. DW, stripped of ions and impurities, serves as a standard for understanding the intrinsic behavior of ZnO photocatalysis, free from any interference from dissolved substances . TW, representative of urban water sources, introduces a spectrum of dissolved ions and organic compounds, potentially influencing the photocatalytic activity of ZnO.…”