Construction of dual vacancies and frustrated Lewis Pairs-modified Bi2WO6 nanosheets for efficient photocatalytic conversion of CO2 to CO

Abstract

Surface vacancy engineering is an attractive modification strategy for constructing efficient photocatalysts. However, the monovacancy-modified photocatalysts exhibit limited activity in the CO2 reduction reaction (CO2RR), primarily due to their low efficiency in separating electron-hole pairs and weak CO2 binding affinity. Herein, a photocatalyst (In2O3-x(OH)y/Bi2WO6-VBi,O) was developed, consisting of Bi/O vacancies-rich Bi2WO6 (Bi2WO6-VBi,O) and In2O3-x(OH)y modified by surface frustrated Lewis pairs (SFLPs). Bi vacancies (VBi) and O vacancies (VO) are categorized as cationic and anionic vacancies, respectively. In comparison to monovacancy-modified photocatalysts, the above photocatalyst can bind the O and C atoms of CO2 to VBi and VO in a bidentate-bonding mode, as opposed to a monodentate-bonding mode, thus achieving robust adsorption and rapid activation of CO2 molecules. The findings from the molecular simulation suggest that dual vacancies and SFLPs enhance CO selectivity by accelerating the desorption step of the intermediate product *CO to CO. Moreover, the directional transfer of electrons from VO to VBi favors the separation of electron-hole pairs. The optimal sample (4.3 %In2O3-x(OH)y/Bi2WO6-VBi,O) has an excellent CO production rate of 191.8 μmol·gcat-1·h−1, 6.6 times that of Bi2WO6, and superior CO selectivity around 100 %. By manipulating dual vacancies and SFLPs, this research contributes to developing novel photocatalysts and elucidates the underlying mechanism of CO2 photoreduction.