Ferroelectric Polarization Modulated Facet‐selective Charge Separation in Bi₄NbO₈Cl Single Crystal for Boosting Visible‐light Driven Bifunctional Water Splitting

Abstract

Developing bifunctional water‐splitting photocatalysts is meaningful, but challenged by the harsh requirements of specific‐facet single crystals with spatially separated reactive sites and anisotropic charge transfer paths contributed by well‐built charge driving force. Herein, tunable ferroelectric polarization is introduced in Bi4NbO8Cl single crystal nanosheets to strengthen the orthogonal charge transfer channels. By manipulating the in‐plane polarization from octahedral off‐centering of Nb5+ and out‐of‐plane polarization from lone pair electron effect of anisotropic Bi3+, both the fast charge recombination in bulk catalyst and the process of charge trapping into surface states can be effectively modulated. Collaborating with modest polarization electric field and facet junction induced built‐in electric field, cooperative charge tractive force is constructed, which reinforces the spatial separation and migration of photogenerated electrons and holes to {110} reductive site facet and {001} oxidation site facet, respectively. While excessive polarization charges impair the facet‐selective charge separation characteristics and conversely promote charge recombination on the surface. As a result, polarity‐optimized Bi4NbO8Cl shows an excellent H2 and O2 evolution rate of 54.21 and 36.08 μmol·h‐1 in the presence of sacrificial reagents under visible light irradiation. This work unveils the function of ferroelectric polarization in tuning the intrinsic facet‐selective charge transfer process of photocatalysts.

Advances in the structural engineering of layered bismuth-based semiconductors for visible light-driven photocatalytic water splitting

“…In addition, Na + -doped Bi 4 NbO 8 Cl (BNOC) is reported to be capable of modulating the polar intensity of the semiconductor by changing the calcination temperature and the amount of the flux during synthesis so as to realize the enhancement of the photocatalytic activity. 68 Na–Bi 4 NbO 8 Cl shares the same morphology of the nanosheet as demonstrated in Fig. 9i but presents a higher remanent polarization in comparison with the pristine one.…”

Band Gap Engineering and Lattice Distortion for Synergetic Tuning Optical Properties of NaNbO3 toward Enhanced Piezo-photocatalytic Activity

“…And the calculated values of piezoelectric coefficient d 33 for 0LMN and 0.10LMN are 5.3 and 15.3 pm/V, respectively, which suggests that 0.10LMN possesses better piezoelectric properties . And better piezoelectric properties can produce a higher piezoelectric polarization (namely, bigger built-in electric field) to accelerate the separation of the photogenerated electrons and holes. − …”

Built-in Electric Field Promotes Interfacial Adsorption and Activation of CO2 for C1 Products over a Wide Potential Window

“…Keeping the above in mind, a series of modification strategies aimed at CO 2 RR electrocatalysts have been developed, such as surface defect designing, − heteroatom doping, , facet engineering, , and strain effect . Recently, the built-in electric field (BIEF) engineering in electrocatalysis has received great attention. − On one hand, it facilitates the electron transfer at the heterointerfaces and finely tunes the charge density around the active sites to enhance the conductivity as well as optimize the adsorption/desorption behavior of key species . On the other hand, the formed space-charge region increases the reactant concentration at the local microenvironment to accelerate the reaction kinetics. , Due to these merits of the BIEF, it has been widely explored in other electrocatalytic reactions, such as oxygen evolution/reduction reactions and nitrate reduction reaction.…”