Role of oxygen vacancy in metal oxide based photoelectrochemical water splitting

Abstract

Photoelectrochemial (PEC) water splitting relies on the optoelectric property of the photoelectrodes. Oxygen vacancy (VO) has attracted increasing attention in tailoring photoelectrodes in the following three aspects: light harvest, charge separation and transfer, and surface reaction kinetics. Even though the VO may increase the recombination as a kind of defects in metal oxide based photoelectrode, a number of recent researches have revealed the beneficial feature of VO in PEC, which is controversial to the former understanding. Thus, a comprehensive analysis about the oxygen vacancy in the metal oxide photoelectrodes will be important for applying VO in achieving high PEC performance. Herein, we contribute a critical review on the role of oxygen vacancy including its formation mechanism, characterization methods, and the influence on the semiconductor and surface catalytic properties. The knowledge will help to clarify the effect of VO in terms of the structure‐performance relationship in the PEC process.

Formation, Detection, and Function of Oxygen Vacancy in Metal Oxides for Solar Energy Conversion

“…The available pathways for characterizing the V O has been discussed in a recent work as shown in Figure . [ 16 ] Herein, we focus on the frequently used effective strategies, including the XPS, EPR, and XAS and some key features of these characterizations are summarized in Table 1 . Meanwhile, the PAS will also be introduced to inspire the V O related research.…”

“…Adapted with permission. [16] Copyright 2021, Wiley-VCH. V O change through XPS and carrier concentration measurement by Mott-Schottky.…”

“…In order to make MOs good candidates for renewable energy conversion, many strategies have been developed, including facet engineering, [ 11 ] cocatalyst loading, [ 12 ] nanostructure engineering, and defect engineering. [ 13 ] Among them, defect engineering, such as doping strategy, [ 14 ] creating oxygen vacancies, [ 15 ] lattice distortion, [ 16 ] is regarded as one of the most effective pathways, thus has been widely applied in designing efficient photocatalysts. As one of the most common defects, oxygen vacancy (V O ) can be created along with the oxide photocatalysts preparation process, leading to drastically changed properties in the MOs.…”

Photocatalytic Reforming of Sucrose and Dextrose for Hydrogen Production on Pd/TiO2

“…The charge lifetime determines photo efficiency, and it is well-known that oxygen vacancies on semiconductors like TiO 2 decrease the holeelectron recombination. [44] The oxygen vacancy tends to drop with metal addition on TiO 2; catalysts with higher metal loading exhibit lower but stable activity.…”

“…The noble metal Pt preferentially interacts with oxygen vacancy sites, [43] ultimately reduce the number of oxygen vacancies and photo efficiency. The charge lifetime determines photo efficiency, and it is well‐known that oxygen vacancies on semiconductors like TiO 2 decrease the hole‐electron recombination [44] . The oxygen vacancy tends to drop with metal addition on TiO 2; catalysts with higher metal loading exhibit lower but stable activity.…”