Multi-electric field modulation for photocatalytic oxygen evolution: Enhanced charge separation by coupling oxygen vacancies with faceted heterostructures

Abstract

A fundamental challenge of photocatalysis is developing efficient strategies to suppress the recombination of photogenerated charge carriers. Herein, ZnO/BiVO4 hierarchical nanostructures were exemplified to demonstrate new concept of multi-electric field-assisted charge separation. The contribution of both facet engineering and defect modulation to the facilitated photocatalysis was confirmed by both experimental observations and theoretical calculations. Such integration of built-in fields in faceted BiVO4 and anisotropic ZnO nanorods, together with the possible Z-scheme at the interfaces resulted into 1.36 mmol•h -1 •g -1 O2 produced under visible light irradiation, and more than one order of magnitude enhanced apparent quantum yield at 450 nm. This work not only provides fundamental insights into the facet-dependent distribution of interfacial defects, but also offers a strategy for the design of faceted heterojunctions with controlled vacancies for significantly enhanced charge separation.

Interfacial Charge Transfer in MoS2/TiO2 Heterostructured Photocatalysts: The Impact of Crystal Facets and Defects

“…For example, {001} and {101} facets of TiO 2 , two most common facets of anatase phase, usually exhibit different adsorption characteristics and redox abilities during the photocatalytic reaction [24,25,26,27]. Our research further revealed the significant contribution of facet-dependent formation of oxygen vacancy defects on the interfacial behavior of photo-induced charge carriers [28]. In this regard, it is a critical point to investigate the impact of crystal facets and defects on the charge separation in MoS 2 -grafted faceted TiO 2 .…”

Photocatalytic Oxygen Evolution from Water Splitting

“…Partial holes on {110} facets were recombined with the electrons that enriched on the endpoints of ZnO nanorods to form a Z‐scheme heterojunction, which led to efficient charge separation. [ 160 ] Besides, the mixed‐phase BiVO 4 (monoclinic and tetragonal phases) were applied as the bridge to construct BiVO 4 /g‐C 3 N 4 Z‐scheme junction for accelerating the charge separation and water oxidation (Figure 25g). [ 161 ] To realize the tight coupling between α ‐Fe 2 O 3 and g‐C 3 N 4 , an SSR route was carried out to synthesize the 2D/2D α ‐Fe 2 O 3 /C–g‐C 3 N 4 (C–g‐C 3 N 4 indicates g‐C 3 N 4 with amorphous carbon).…”

Strong Light–Matter Interactions in Au Plasmonic Nanoantennas Coupled with Prussian Blue Catalyst on BiVO4 for Photoelectrochemical Water Splitting

“…The effect of oxygen vacancies on the BiVO 4 PEC performance is still under debate in the literature. Recent works indicate that oxygen vacancies can have multiple roles on the PEC‐WS performance of metal oxides . From the positive side, it is commonly accepted that oxygen vacancies inside the bulk medium improve the free carrier concentration and consequently lead to better charge carrier transport .…”