The Positive Versus Negative Effects of Defect Engineering for Solar Water Splitting: A Review

Abstract

Although defect design is an essential means of improving the performance of photocatalytic materials, defect introduction is not always beneficial. Current defect engineering focuses on avoiding or modifying introduced defects to mitigate their adverse effects on solar water splitting performance. This review comprehensively summarizes the strategies for defect introduction and discusses their crucial roles in solar water splitting. Focusing on the dual effects of defects, the most basic schemes for preparing favorable defects through pretreatment and posttreatment methods are reviewed. In addition, the review focuses on strategies for overcoming or mitigating the detrimental effects of defects to improve the performance of photocatalysts. Finally, the challenges and prospects of developing a defect‐based photocatalyst design strategy are outlined. This review provides a reference for preparing defect‐based photocatalysts for conducting more in‐depth research on defects. Additionally, it offers ideas for utilizing unfavorable defects and converting them into favorable defects for performance improvement.

Converting Undesirable Defects into Activity Sites Enhances the Photoelectrochemical Performance of The ZnIn2S4 Photoanode

“…Extensive research has shown that heteroatom doping certainly introduces some detrimental defects or causes negative effects, limiting the improvement of PEC performance. [ 9 ] With an increase in the amount of selenium doping in Fe 2 O 3 , the depletion region becomes too narrow to ensure effective charge separation. [ 10 ] Excessive molybdenum doping into BiVO 4 induces the formation of new trap states, moderating the Fermi‐level pinning effect and leading to persistent recombination of carriers.…”

Nonstoichiometric In–S group yielding efficient carrier transfer pathway in In2S3 photoanode for solar water oxidation

“…Doping and vacancy defects in metal sulfides, especially for those introducing S vacancies or O doping, are effective strategies for enhancing carrier transport dynamics. Heteroatom doping or vacancies do not always favor carrier transport and introduce impurities that lead to severe carrier recombination and hinder photogenerated electron–hole pair transfer 18 …”

Facile Estimation of Surface Oxygen Vacancies in Co3O4 Catalysts with a Colorimetric Method

“…At present, metal oxide has attracted great attention in catalytic materials for many applications (typically energy conversion and pollutant degradation) due to their low cost, availability, chemical stability, and structural diversity. , Oxygen vacancy (Ov), as an intrinsic defect of the oxide, always appears in metal oxide crystals. Ov has been proven to tune the coordination environment, change the electronic structure, and vary the adsorption tendency of active sites, thus improving the catalytic activity of metal oxides. − The introduction and regulation of Ov in a metal oxide crystal have become one research hotspot in the catalytic field. − Therefore, quantification of surface Ov in metal oxide is vital for understanding the quantitative structure–activity relationship, which will provide a powerful guidance for further design and application of Ov. − …”