A Comprehensive Review on the Boosted Effects of Anion Vacancy in the Heterogeneous Photocatalytic Degradation, Part II: Focus on Oxygen Vacancy

Abstract

Environmental problems, including the increasingly polluted water and the energy crisis, have led to a need to propose novel strategies/methodologies to contribute to sustainable progress and enhance human well-being. For these goals, heterogeneous semiconducting-based photocatalysis is introduced as a green, eco-friendly, cost-effective, and effective strategy. The introduction of anion vacancies in semiconductors has been wellknown as an effective strategy for considerably enhancing the photocatalytic activity of such photocatalytic systems, giving them the advantages of promoting light harvesting, facilitating photogenerated electron−hole pair separation, optimizing the electronic structure, and enhancing the yield of reactive radicals. This Review will introduce the effects of anion vacancy-dominated photodegradation systems. Then, their mechanism will illustrate how an anion vacancy changes the photodegradation pathway to enhance the degradation efficiency toward pollutants and the overall photocatalytic performance. Specifically, the vacancy defect types and the methods of tailoring vacancies will be briefly illustrated, and this part of the Review will focus on the oxygen vacancy (OV) and its recent advances. The challenges and development issues for engineered vacancy defects in photocatalysts will also be discussed for practical applications and to provide a promising research direction. Finally, some prospects for this emerging field will be proposed and suggested. All permission numbers for adopted figures from the literature are summarized in a separate file for the Editor.

A Comprehensive Review on the Boosted Effects of Anion Vacancy in the Photocatalytic Solar Water Splitting: Focus on Sulfur Vacancy

“…For example, a summarized study has been published on the effects of OV-based metal oxide photoanodes for application in the photocatalytic water splitting process . The vital roles of vacancy engineering in boosting solar-driven photocatalysis activity have also been reviewed. , Some reviews studied various vacancy defects categories of the vacancy-engineered photocatalysts fabrication, the characterization techniques, and the vacancy defects roles in various photocatalytic fields, including water splitting, photodegradation of organic compounds, CO 2 conversion, generation of hydrogen peroxide, and N 2 fixation. − In 2023, we illustrated the functions, synthesis, characterization procedures, and applications of semiconductors mediated with O, N, S, and halogen vacancies in the photocatalytic degradation process. , Despite a recent clear upward trend in the number of research studies on SV photocatalysts, there are few relevant overviews on the mechanism and application of SV photocatalysts. The SV generation methods via various synthetic routes and the quality of SV creation during the synthesis procedures were studied by multiple researchers.…”

α-Fe2O3/Nb2O5/C Nanorods for Selective Photoelectrocatalytic Oxidation of 5-Hydroxymethylfurfural under Solar Light

“…In addition, Fe 3+ can be reduced to Fe 2+ by electrons on the conduction band (CB) of α-Fe 2 O 3 , thus reducing the loss of Fe 2+ and the generation of solid sludge . Nevertheless, the single α-Fe 2 O 3 photocatalyst still exhibited poor photocatalytic activity due to the slow migration kinetics and separation of photogenerated carriers. , It is shown that the construction of heterojunctions can effectively improve the separation efficiency of photogenerated carriers and enhance the catalytic activity of photocatalysts. − Particularly, heterostructures with more interfacial regions shorten the charge transfer distance and time, thereby improving the photocatalytic activity, which leads to high-rate capability and efficient catalytic activities . The emerging superlattice structure is laminated composites formed by alternating growth of thin layers of different materials .…”

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

“…For example, various types of AV defects, the synthesis procedures for vacancy-engineered photocatalysts for water splitting, etc. have been discussed in a review by Ding et al In 2023, we collected and discussed the functions, synthesis methods, and applications of semiconductors mediated with O, N, S, and halogen vacancies in PC degradation. , …”