Surface restoration of polycrystalline Sb2Se3 thin films by conjugated molecules enabling high-performance photocathodes for photoelectrochemical water splitting

• Published in: Applied catalysis. B, Environmental Vol. 286; p. 119890
• Main Authors: Tan, Jeiwan, Yang, Wooseok, Lee, Hyungsoo, Park, Jaemin, Kim, Kyungmin, Hutter, Oliver S., Phillips, Laurie J., Shim, Sanggi, Yun, Juwon, Park, Youngsun, Lee, Jeongyoub, Major, Jonathan D., Moon, Jooho
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05.06.2021; Elsevier BV
• Subjects: Antimony compounds; Buried junction; Conjugated amino acid; Defect passivation; Onset potential; para-Aminobenzoic acid; Photocathodes; Photocurrent density; Photoelectric effect; Photoelectric emission; Photoelectrons; Polycrystals; Restoration; Selenides; Splitting; Surface defects; Thin films; Titanium dioxide; Water splitting; Buried junction; Photocurrent density; Defect passivation; Conjugated amino acid; Onset potential
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2021.119890

Interface modification with para-aminobenzoic acid passivated the interface states, causing rapid photoelectron transport through the Sb2Se3/TiO2 interface and resulting in high onset potential and photocurrent density in the photocathode for photoelectrochemical water splitting. [Display omitted] •Surface defects in Sb2Se3 photocathode limit the photovoltage development.•Interface modification not only passivates the interface states, but also allows rapid photoelectron transport.•Record-high onset potential, photocurrent density, and half-cell solar-to-hydrogen efficiency are achieved. Achieving both high onset potential and photocurrent in photoelectrodes is a key challenge while performing unassisted overall water splitting using tandem devices. We propose a simple interface modification strategy to maximize the performance of polycrystalline Sb2Se3 photocathodes for photoelectrochemical (PEC) water splitting. The para-aminobenzoic acid (PABA) modification at Sb2Se3/TiO2 interface enhanced both the onset potential and photocurrent of the Sb2Se3 photocathodes. The surface defects in the polycrystalline Sb2Se3 limited the photovoltage production, lowering the onset potential of the photocathode. Surface restoration using the conjugated PABA molecules efficiently passivated the surface defects on the Sb2Se3 and enabled the rapid photoelectron transport from the Sb2Se3 to the TiO2 layer. The PABA treated Sb2Se3 photocathode exhibited substantially improved PEC performance; the onset potential increased from 0.35 to 0.50 V compared to the reversible hydrogen electrode (VRHE), and the photocurrent density increased from 24 to 35 mA cm−2 at 0 VRHE.