Photocatalytic Properties Dependent on the Interfacial Defects of Intergrains within TiO₂ Mesocrystals

Abstract

The regulation of interfacial defects of nanocrystals aligned orderly in a superstructured photocatalyst is an effective approach to improve the photocatalytic performance. However, the synthesis of ordered self-assemblies with abundant interfacial defects and reactive sites is hard to achieve, and applications are limited due to the unclear physicochemical properties, which result from the unique mesocrystalline microstructures. It is reported herein that the photocatalytic properties depend on the interfacial defects of intergrains in anatase TiO mesocrystals (TMCs). Research reveals that the photocatalytic activity largely depends on defects, such as lattice distortion and oxygen vacancies, which are located at highly aligned interfaces of intergrains within TMCs. Moreover, the mesocrystalline TiO photocatalysts exhibit higher photocatalytic performance in organic degradation and hydrogen evolution, compared with single crystals and polycrystals; this can be ascribed to an appropriate amount of interfacial defects at the intergrains and improved carrier separation efficiency through the highly oriented interfaces. In addition, the photocatalytic performance of the TMCs could be further improved through regulation of defects by undergoing an annealing process under a redox atmosphere. This work can provide an avenue to defect engineering for improved photocatalytic performance.

Interfacial oxygen vacancies yielding long-lived holes in hematite mesocrystal-based photoanodes

“…The high-resolution TEM (HRTEM) image obtained from the region comprised two adjacent nanocrystals with an interface clearly indicates parallel crystal lattices (Fig. 1b), further proving the structural characteristics of MC 29 . There are three sets of lattice fringes with lattice spacing ( d ) of 0.25 nm, which corresponds to the (110) plane of hematite, and with interfacial angle of 60 o , which is consistent with the SAED result.…”

2D mesoporous ultrathin Cd0.5Zn0.5S nanosheet: Fabrication mechanism and application potential for photocatalytic H2 evolution

“…The distinct feature of type IV isotherms with an H1 hysteresis loop was observed for the Cd0.5Zn0.5S nanosheets and 7%-NiCo2S4/Cd0.5Zn0.5S. This indicates that the mesopores were uniformly cylindrical and that the introduction of NiCo2S4 did not alter the mesoporous feature of the nanosheets [48,49]. Nevertheless, the Cd0.5Zn0.5S nanoparticles exhibited typical H3 curves, similar to other aggregated particles.…”

Construction of 2D‐ZnS@ZnO Z‐Scheme Heterostructured Nanosheets with a Highly Ordered ZnO Core and Disordered ZnS Shell for Enhancing Photocatalytic Hydrogen Evolution

“…EPR can sensitively detect the defects in photocatalysts . Figure a shows the EPR spectra of ZnO, ZnS, and OS‐60‐6 before and after irradiation saturated with O 2 .…”

“…EPR can sensitively detect the defects in photocatalysts. [37] Figure 6a shows the EPR spectra of ZnO, ZnS, and OS-60-6 before and after irradiation saturated with O 2 . The signal at g = 1.949 and 1.998 can be assigned to the zinc interstitials (Zn i ) and V O + , respectively.…”