Photo-electrochemical reduction of carbon dioxide can be currently considered as the most efficient approach for CO2 transformation into clean and storable fuels and chemicals. In a Photo-Electrochemical Cell (PEC) rapid spatial separation of the photo-generated carriers and their transport kinetics within the photo-electrodes materials are fundamental to achieve high-performance devices avoiding charges recombination. In 2010[1] Wang showed how the piezoelectric dipole arising from external stimuli in non-centrosymmetric crystals can efficiently modify the charge transfer properties both in the bulk phase and at the surface of semiconductors[2]. In this regard, photoactive materials simultaneously displaying semiconducting behavior and ferroelectric properties (i.e. ferroelectric-enhanced piezo-phototronic materials) represent a promising option as PEC photo-electrodes, allowing the modification of cells efficiency by electrically polarizing the materials. Whit this in mind Aurivillius compounds seem to be the perfect candidates. This peculiar class of perovskites, thanks to their unique layered structure, generally allows the migration of photo-generated holes and electrons within different areas of the materials, facilitating charge separation and incrementing cells efficiency. In addition, they are endowed with strong spontaneous ferroelectric polarization which can be used to exploit the piezo-phototronic effect. 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 details. 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. In this work, BiTO and BiMO photo-electrodes were fabricated and accurately optimized to obtain both hierarchically oriented nanostructures and thin-film layers via in situ hydrothermal deposition and through a sol-gel/spin coating coupled process respectively. These architectures were therefore compared to evaluate the effect of ferroelectric potential on the photo-electrochemical performances of the optimized photo-electrodes. Current density increments of about 50% under the optimal ferroelectric polarization were obtained for the spin-coated samples and enhanced charge transfer abilities were also registered demonstrating the possibility to adopt ferroelectric polarization coupled with an external bias to effectively control the migration of photo-generated charges in the CO2 photo-electrochemical reduction. ______________ References: [1]Whang, Z. L.; Nano Today 2010, 5, 540-552. [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.
Development of Auriviilius-based photo-electrodes for the ferroelectric-enhanced photoelectrochemical reduction of CO2
S Casadio;A Gondolini;N Sangiorgi;A Sanson
2022
Abstract
Photo-electrochemical reduction of carbon dioxide can be currently considered as the most efficient approach for CO2 transformation into clean and storable fuels and chemicals. In a Photo-Electrochemical Cell (PEC) rapid spatial separation of the photo-generated carriers and their transport kinetics within the photo-electrodes materials are fundamental to achieve high-performance devices avoiding charges recombination. In 2010[1] Wang showed how the piezoelectric dipole arising from external stimuli in non-centrosymmetric crystals can efficiently modify the charge transfer properties both in the bulk phase and at the surface of semiconductors[2]. In this regard, photoactive materials simultaneously displaying semiconducting behavior and ferroelectric properties (i.e. ferroelectric-enhanced piezo-phototronic materials) represent a promising option as PEC photo-electrodes, allowing the modification of cells efficiency by electrically polarizing the materials. Whit this in mind Aurivillius compounds seem to be the perfect candidates. This peculiar class of perovskites, thanks to their unique layered structure, generally allows the migration of photo-generated holes and electrons within different areas of the materials, facilitating charge separation and incrementing cells efficiency. In addition, they are endowed with strong spontaneous ferroelectric polarization which can be used to exploit the piezo-phototronic effect. 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 details. 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. In this work, BiTO and BiMO photo-electrodes were fabricated and accurately optimized to obtain both hierarchically oriented nanostructures and thin-film layers via in situ hydrothermal deposition and through a sol-gel/spin coating coupled process respectively. These architectures were therefore compared to evaluate the effect of ferroelectric potential on the photo-electrochemical performances of the optimized photo-electrodes. Current density increments of about 50% under the optimal ferroelectric polarization were obtained for the spin-coated samples and enhanced charge transfer abilities were also registered demonstrating the possibility to adopt ferroelectric polarization coupled with an external bias to effectively control the migration of photo-generated charges in the CO2 photo-electrochemical reduction. ______________ References: [1]Whang, Z. L.; Nano Today 2010, 5, 540-552. [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.
