In recent years, bismuth-based photocatalysts have been receiving increasing attention in photocatalysis, due to their appropriate bandgap and tunable surface structure, which make them suitable also for the photocatalytic reduction of CO21. Their performances, however, are still limited by the fast charge carriers recombination. Recently, the exploitation of piezo/ferro-electric potentials in photo-active semiconductors has been adopted as an effective strategy to modulate the charge transfer properties both in the bulk phase and at the surface of semiconductors (i.e. piezo-phototronic effect)2. In this perspective Bismuth-based Aurivillius compounds, owing to their usually strong spontaneous ferroelectric polarization represent a promising option as cell photo-electrodes, allowing the increase of cell efficiency by electrically polarizing the materials. In addition, thanks to their unique layered structure, this peculiar class of perovskites allows the migration of photo-generated holes and electrons within different areas of the materials, thus intrinsically facilitating charge separation. In this work, the utilization of different Aurivillius compounds (i.e. Bi4Ti3O12 - BiTO, and Bi2MoO6 - BiMO) as photo-electrode materials for solar conversion has been studied in detail. The use of BiTO and BiMO for the photocatalytic reduction of CO2 has recently been reported, however, the main strategies to develop optimized ferroelectric-enhanced photo-electrodes of these materials and their utilization for the ferroelectric potential-assisted CO2 reduction has never been fully investigated. BiTO and BiMO photo-electrodes were fabricated and accurately optimized to obtain both hierarchically oriented nanostructures with different morphologies (i.e. nanosheet/nanorod arrays), and thin-film layers via in situ hydrothermal deposition and through a sol-gel/spin coating coupled process respectively. The effect of the ferroelectric potential on the photo-electrochemical performances of the optimized photo-electrodes with different architectures was therefore accurately studied. Density current increments and enhanced charge transfer ability were registered under the optimal ferroelectric polarization which was directly reflected in the CO2 photo-electrochemical reduction performances. This work, therefore, demonstrates the possibility to adopt ferroelectric polarization coupled with an external bias to effectively control the migration of photo-generated charges in bismuth-based Aurivillius semiconductors for the CO2 photo-electrochemical reduction. References [1]Liu, X., Xiao, J., Ma, S., Shi, C., Pan, L., Zou, J.-J.; ChemNanoMat 2021, 7, 684-698. [2]Pan, L.; Sun, S.; Chen, Y.; Wang, P.; Wang, J.; Zhang, X.; Zou, J.-J.; Whang, Z. L.; Adv. Energy Mater. 2020, 10, 2000214.
Bismuth-based Aurivillius photo-electrodes for the ferroelectric-enhanced photoelectrochemical reduction of CO2
S Casadio;A Gondolini;N Sangiorgi;A Sanson
2022
Abstract
In recent years, bismuth-based photocatalysts have been receiving increasing attention in photocatalysis, due to their appropriate bandgap and tunable surface structure, which make them suitable also for the photocatalytic reduction of CO21. Their performances, however, are still limited by the fast charge carriers recombination. Recently, the exploitation of piezo/ferro-electric potentials in photo-active semiconductors has been adopted as an effective strategy to modulate the charge transfer properties both in the bulk phase and at the surface of semiconductors (i.e. piezo-phototronic effect)2. In this perspective Bismuth-based Aurivillius compounds, owing to their usually strong spontaneous ferroelectric polarization represent a promising option as cell photo-electrodes, allowing the increase of cell efficiency by electrically polarizing the materials. In addition, thanks to their unique layered structure, this peculiar class of perovskites allows the migration of photo-generated holes and electrons within different areas of the materials, thus intrinsically facilitating charge separation. In this work, the utilization of different Aurivillius compounds (i.e. Bi4Ti3O12 - BiTO, and Bi2MoO6 - BiMO) as photo-electrode materials for solar conversion has been studied in detail. The use of BiTO and BiMO for the photocatalytic reduction of CO2 has recently been reported, however, the main strategies to develop optimized ferroelectric-enhanced photo-electrodes of these materials and their utilization for the ferroelectric potential-assisted CO2 reduction has never been fully investigated. BiTO and BiMO photo-electrodes were fabricated and accurately optimized to obtain both hierarchically oriented nanostructures with different morphologies (i.e. nanosheet/nanorod arrays), and thin-film layers via in situ hydrothermal deposition and through a sol-gel/spin coating coupled process respectively. The effect of the ferroelectric potential on the photo-electrochemical performances of the optimized photo-electrodes with different architectures was therefore accurately studied. Density current increments and enhanced charge transfer ability were registered under the optimal ferroelectric polarization which was directly reflected in the CO2 photo-electrochemical reduction performances. This work, therefore, demonstrates the possibility to adopt ferroelectric polarization coupled with an external bias to effectively control the migration of photo-generated charges in bismuth-based Aurivillius semiconductors for the CO2 photo-electrochemical reduction. References [1]Liu, X., Xiao, J., Ma, S., Shi, C., Pan, L., Zou, J.-J.; ChemNanoMat 2021, 7, 684-698. [2]Pan, L.; Sun, S.; Chen, Y.; Wang, P.; Wang, J.; Zhang, X.; Zou, J.-J.; Whang, Z. L.; Adv. Energy Mater. 2020, 10, 2000214.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
