Role of Vacancies in Photocatalysis: A Review of Recent Progress

Abstract

Photocatalysis via direct solar-to-chemical energy conversion is an intriguing approach for alleviating the pressure of high energy consumption caused by social development. However, photocatalytic efficiency is greatly restricted by unsatisfactory light-harvesting capacity, high carrier recombination rates, and sluggish reaction kinetics. Indeed, vacancy engineering is an attractive strategy to regulate photocatalytic reaction performance to maximize the utilization and storage of solar energy. In this review, we summarize recent progress about the important roles of vacancy defects on solar-driven photocatalytic applications. The current advanced characterization techniques, especially for in situ/operando techniques, are first presented for elucidating the structure-performance relationships of defective semiconductors in photocatalysis. Subsequently, the crucial roles of vacancies in enhancing photocatalytic performance are highlighted from three important processes: light absorption, carrier separation and migration, and surface reaction. Finally, based on the above understanding, perspectives and opportunities about defective materials are considered for various photocatalytic applications.

Realizing Superior Redox Kinetics of Hollow Bimetallic Sulfide Nanoarchitectures by Defect‐Induced Manipulation toward Flexible Solid‐State Supercapacitors

“…However, the anodic peak of S v -CuCo 2 S 4 -4 is positively shifted, and the corresponding cathodic peak shifts to lower potential, which is due to the decreased redox kinetics. This may be attributed to the fact that excessive vacancies lead to a decrease in spin-polarized electrons, which reduces the degree of freedom of the electrons and lowers the electrical conductivity, [39][40][41] leading to increased barrier for redox reactions. Note that the CC substrate provides a negligible contribution to the total stored charge (≈3.9% relative to S v -CuCo 2 S 4 -3), as shown in Figure S8 (Supporting Information).…”

Recent Progress in LDH@Graphene and Analogous Heterostructures for Highly Active and Stable Photocatalytic and Photoelectrochemical Water Splitting

“…The SEM image discloses a perfect decent phase of NiFe−LDH nanoplatelets over the entire NAs assembly (Figure 10(b–d)). This ternary TiO 2 /rGO/NiFe−LDH NAs displayed superior PEC water splitting performances with highest current density of 1.74 mA cm −2 , at 0.6 V and efficiency of 0.58%, at 0.13 V. The superior PEC water oxidation and stability could be ascribed to the synergistic effect of oxygen vacancies and N‐doping, which causes sturdy chemical bonding contacts among TiO 2 , rGO, and NiFe−LDH [140] . The mechanistic path of PEC water oxidation by ternary NAs shows that rGO with elevated electron storage properties, receive photogenerated electrons of TiO 2 and hole trapping by NiFe−LDH due to its dynamic active sites for PEC O 2 production (Figure 10(e)).…”

Heterojunction-based photocatalytic nitrogen fixation: principles and current progress

“…The nitrogen fixation proceeded via oxidation of methanol to CO2and its reactionary intermediates and subsequent reduction of N2 via CO2radicals. It is well known that the introduction of defects is favourable for enhancing photoactivity by trapping electronhole pairs and increasing the propensity of charge carriers to participate in the surface reaction 113 . Considering the specificity of the nitrogen reduction reaction, the introduction of nitrogen vacancies into the crystal lattice of the photocatalyst could be useful for trapping and activating N2 molecules.…”