Fabrication of a Sb₂Se₃/CuSbS₂ Heterojunction Photocathode for Photoelectrochemical Water Splitting

Abstract

Antimony selenide (Sb 2 Se 3 ) is a promising semiconductor lightabsorbing material for photoelectrochemical (PEC) water splitting to produce hydrogen. Effectively promoting the separation of photogenerated carriers and extracting holes from the light-absorbing layer to the back electrode are key to improving the PEC performance. In this work, the Sb 2 Se 3 /CuSbS 2 heterojunction was prepared by a facile and cost-effective method that involves solution synthesis, spincoating, and thermal treatment processes. The PEC performance of the Sb 2 Se 3 /CuSbS 2 heterojunction was optimized by adjusting the drying temperature of the prepared CuSbS 2 films. After surface passivation with TiO x , the Sb 2 Se 3 surface defects were passivated and the PEC devices were well protected, and the Pt/TiO x /Sb 2 Se 3 /CuSbS 2 / FTO photocathode possessed a photocurrent density of 18.0 mA cm −2 at 0 V versus reversible hydrogen electrode, about four times that without the CuSbS 2 layer. This excellent PEC performance benefits from the construction of heterojunctions with suitable energy band alignment and the improved electron−hole pair separation and transfer efficiency. This work provides an effective strategy and important guidelines for improving the PEC efficiency of the Sb 2 Se 3 photocathode by introducing CuSbS 2 to form a heterojunction.

Heterojunction Bi2Se3/Sb2Se3 on Flexible Mo Metal Foils for Photoelectrochemical Water Splitting Applications

“…The literature survey indicates that although considerable work has been done on Bi 2 Se 3 - and Sb 2 Se 3 ‑based photoelectrodes on hard non-bendable substrates such as silicon, ITO/FTO-coated glass/quartz, etc, − ,− photoelectrodes on flexible substrates can be beneficial for the production of roll-to-roll devices, thereby bringing a substantial reduction of weight (with respect to glass or hard substrates) and thus easy for transportation, installation, and maintenance. − Therefore, photoelectrodes with good flexibility, robustness, and chemical and thermal stabilities are high in demand for futuristic applications involving water splitting . However selecting flexible substrates is a challenging task because it depends on several parameters such as melting point, thermal and electrical conductivity, and robustness.…”

“…Sb 2 Se 3 has been explored as an efficient photocatalyst in PEC water splitting due to several advantages including an optimum band gap (1.1–1.4 eV) which allows strong absorption of the IR–visible light, low toxicity, conduction band minimum located at −0.28 V vs NHE, high optical absorption coefficient (∼10 5 cm –1 ), and a high relative permittivity value of 15 offering effective separation of photogenerated charges due to lower exciton binding energy. However, to further enhance its functionalities, various kinds of heterojunction structures, nanostructures, dual-stacked system, z-scheme, etc., have been proposed. − Guo et al prepared a MoS 2 /Sb 2 Se 3 photoelectrode on fluorine-doped tin oxide (FTO)-coated glass and obtained a maximum photocurrent density of −10 mA/cm 2 in a 0.5 M Na 2 SO 4 solution . Zhang et al prepared a Pt/TiO 2 /CdS/Sb 2 Se 3 (Se-annealed) photocathode on a Mo-coated soda lime glass substrate, investigated the PEC properties under a 0.5 M Na 2 SO 4 electrolyte, and achieved a photocurrent density of −8.6 mA/cm 2 .…”