Selective Bonding Effect of Heterologous Oxygen Vacancies in Z-Scheme Cu₂O/SrFe_0.5Ta_0.5O₃ Heterojunctions for Constructing Efficient Interfacial Charge-Transfer Channels and Enhancing Photocatalytic NO Removal Performances

Abstract

An interfacial structure is crucial to the photoinduced electron transport for a heterostructure photocatalyst. Constructing an interfacial electron channel with an optimized interfacial structure can efficiently improve the electron-transfer efficiency. Herein, the rapid electron-transfer channels were built up in a Cu2O/SrFe0.5Ta0.5O3 heterojunction (Cu2O/SFTO) based on the selective bonding effect of heterologous surface oxygen vacancies in the SFTO component. The heterologous surface oxygen vacancies, namely, VO–Fe and VO–Ta, respectively, adjacent to Fe and Ta atoms, were introduced into fabricating the Z-scheme Cu2O/SFTO heterojunction. Compared with sample Cu2O/SFTO with VO–Fe, the photocatalytic NO removal efficiency of sample Cu2O/SFTO with VO‑Fe and VO‑Ta was increased by 22.5%. The enhanced photocatalytic performance originated from the selective bonding effect of heterologous VO–Fe and VO–Ta on the interfacial electron-separating and -transfer efficiency. VO–Fe is the main body to construct the interfacial electron-transfer channels by forming interfacial Fe–O–Cu­(I) bonds, which causes lattice distortion at the interface, and VO–Ta can optimize the structure of interfacial channels by balancing the electron density of SFTO to control the average space of the interface transition zone. This research provides a new cognitive perspective for constructing double perovskite oxide-based heterostructure photocatalysts.

Perspective on Defective Semiconductor Heterojunctions for CO2 Photoreduction

“…An S-scheme heterojunction is composed of reduction photocatalysts (RP) and oxidation photocatalysts (OP) with direct and intimate contact, staggered band structure, and a distinct charge-transfer route, maintaining a strong redox potential for photocatalysis. In the past few years, numerous efforts have been devoted to constructing S-scheme heterojunctions for CO 2 photoreduction, and it was found that high interface transfer resistance is a bottleneck for their applications in photocatalysis. ,, …”

“…Numerous efforts have been made to construct heterojunctions to boost CO 2 photoreduction (see the related review 4 ); however, the photocatalytic activity of existing heterojunctions is unsatisfactory, mainly due to their low interfacial charge transfer efficiency as well as sluggish surface reaction kinetics. 2,5,6 Structure defects, such as point defects (cation or anion vacancies), line defects (dislocations), facet defects (grain boundaries), and volume defects (holes), are common in prepared materials, while their contents are too low to have an effect on photocatalysis. When abundant defects, such as the most common anion vacancies, are created on the surfaces of semiconductors, their great potential on boosting photocatalysis emerges.…”

“…In the past few years, numerous efforts have been devoted to constructing S-scheme heterojunctions for CO 2 photoreduction, and it was found that high interface transfer resistance is a bottleneck for their applications in photocatalysis. 2,5,6 Recently, Chen et al pointed out that interface V O enhances the electronic interactions between g-C 3 N 4 and BiOCl in their hybrids and thus provides a fast channel for interface charge transfer, leading to a significant enhancement for photocatalytic CO 2 reduction activity relative to that without V O . 15 The related mechanism was further investigated by other groups, and three kinds of effects associated with interface V O in photocatalysis were revealed successively: (i) The introduction of the defect state as electron-trap sites to boost interface charge transfer and to promote CO 2 activation.…”

“…(iii) The spatial separation of redox sites promotes forward reactions and suppresses backward ones. Numerous efforts have been made to construct heterojunctions to boost CO 2 photoreduction (see the related review); however, the photocatalytic activity of existing heterojunctions is unsatisfactory, mainly due to their low interfacial charge transfer efficiency as well as sluggish surface reaction kinetics. ,, …”

NaNbO3/NaTaO3 Superlattices: Cation-Ordering Improved Band-Edge Alignment for Water Splitting and CO2 Photocatalysis

“…Also, LaCrO 3 –NaTaO 3 solid solutions have performed improved photocatalytic reactions with an enhanced electron population due to a charge compensation mechanism that sensitizes the tantalate to visible light . Similarly, BiFeO 3 , NaNbO 3 , KNbO 3 , KTaO 3 , NaTaO 3 , and other tantalate-based − heterostructures have been synthesized and showed benefits compared to their bulk parts.…”