Enhanced interfacial charge transfer between CsPbBr3 quantum dots and surface-modified TiO2/FTO photoanodes for photocurrent generation
By Nuket, P.; Akaishi, Y.; Yoshimura, G.; Vas-Umnuay, P.; Kida, T.
Published in Materials Today Nano
2022
Abstract
Charge separation and charge transfer of electrode materials play an important factor to improve the photoelectrochemical (PEC) performance. In this work, the photocurrent generation via PEC oxidation of methanol was studied using surface-modified TiO2-coated fluorine-doped tin oxide (FTO) as a photoanode in combination with CsPbBr3 quantum dots (QDs) dispersed in an electrolyte solution. Detailed studies revealed that surface modification of the TiO2 layer was crucial for good interfacial adhesion of CsPbBr3 QDs, which were surrounded by hydrophobic ligands, with the TiO2 surface. Self-assembled monolayers of octadecylphosphonic acid (ODPA) were applied on the TiO2 surface, resulting in the change of hydrophilic nature to a superhydrophobic surface. The photoluminescence measurement of the ODPA-modified TiO2/FTO photoanode demonstrated a significantly higher photoluminescence intensity than that of the unmodified one, indicating that CsPbBr3 QDs were well adsorbed on the TiO2 surface. The photocurrent was generated via methanol oxidation by holes in CsPbBr3 QDs. The current-voltage measurements revealed that in the presence of methanol, the current density was increased from 1.2 mA/cm2 (without methanol) to the maximum of 1.6 mA/cm2 under visible light irradiation, indicating that methanol was a sacrificial hole scavenger. Electrons in QDs were injected into the photoanode which led to enhanced charge separation and PEC performance. As a consequence, the multicomponent ODPA-modified TiO2/FTO photoanode in combination with CsPbBr3 QDs together with the efficient hole scavenger of methanol in the system has been shown to promote the PEC oxidation performance.