Photoelectrochemical Properties of Pulse-Reverse Electrodeposited Sb<sub>2</sub>Se<sub>3</sub>/TiO<sub>2</sub> Nanotube Photoanodes' Controlled Sb<sub>2</sub>Se<sub>3</sub> Overlayer

Abstract

Constructing heterostructures is a promising strategy to improve the photoelectrochemical (PEC) performance of photoanodes in PEC water-splitting systems. The effect on PEC performance is dependent on the deposition conditions of the overlayer in the heterostructured photoanode. Herein, the deposition condition of the antimony selenide (Sb2Se3) overlayer by adjusting the duty cycle and cycle number during pulse-reverse electrodeposition. This aims to assess its impact on the PEC characteristics of the Sb2Se3 overlayered titanium dioxide (Sb2Se3/TiO2) nanotube photoanode. Adequate pulse-off time in the duty cycle ensures sufficient permeation of deposition electrolyte into the inner wall of TiO2 nanotube, leading to uniform Sb2Se3 deposition. On the other hand, an excessive cycle number negatively affects PEC performance, as Sb2Se3 agglomeration blocks the pores of the TiO2 nanotube. Consequently, the Sb2Se3/TiO2 nanotube photoanode, when fabricated with the optimal pulse-off time and cycle number, exhibits enhanced PEC performance. This is due to efficient charge transfer/separation facilitated by the p-n heterojunction and improved light absorption. These insights offer valuable guidance in choosing the appropriate fabrication processes for heterostructured photoanodes in efficient PEC water-splitting systems.