Abstract
Solar-light driven CO2 reduction into value-added chemicals and fuels emerges as a significant approach for CO2 conversion. However, inefficient electron-hole separation and the complex multi-electrons transfer processes hamper the efficiency of CO2 photoreduction. Herein, we prepare ferroelectric Bi3TiNbO9 nanosheets and employ corona poling to strengthen their ferroelectric polarization to facilitate the bulk charge separation within Bi3TiNbO9 nanosheets. Furthermore, surface oxygen vacancies are introduced to extend the photo-absorption of the synthesized materials and also to promote the adsorption and activation of CO2 molecules on the catalysts’ surface. More importantly, the oxygen vacancies exert a pinning effect on ferroelectric domains that enables Bi3TiNbO9 nanosheets to maintain superb ferroelectric polarization, tackling above-mentioned key challenges in photocatalytic CO2 reduction. This work highlights the importance of ferroelectric properties and controlled surface defect engineering, and emphasizes the key roles of tuning bulk and surface properties in enhancing the CO2 photoreduction performance.
Highlights
Solar-light driven CO2 reduction into value-added chemicals and fuels emerges as a significant approach for CO2 conversion
Bi3TiNbO9 (BNT) nanosheets were synthesized by a hydrothermal route with NaOH as the mineralizer, followed by treatments with different amounts of glyoxal (BNT-OVX, X = 1, 2, 3) to introduce oxygen vacancies (OVs) (Fig. 1a)
(Supplementary Fig. 24), in line with a polarization-induced electric field formed between bright and dark regions. These results strongly suggest the presence of ferroelectric spontaneous polarization in Bi3TiNbO9 nanosheets, and that corona poling enhances the ferroelectric polarization, which results in more efficient charge separation
Summary
Solar-light driven CO2 reduction into value-added chemicals and fuels emerges as a significant approach for CO2 conversion. The photocatalytic performance depends strongly on the photogenerated charge separation and transfer kinetics in the bulk and on the surface of photocatalysts[9]. Efforts have been made to improve the photocatalytic performance by using cocatalyst to increase the charge separation[10], surface modification strategies to enrich the reactive sites[11] and formation of heterojunction structures or facet junctions to enhance anisotropic photogenerated charge migration[12,13,14]. The displacement of positive and negative charges allows for spontaneous polarization within the crystal; a strong driving force for bulk charge separation and among others, ferroelectric SrTiO316 and BiFeO317 have been reported to enhance the oxygen production performance of photoanodes.
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