Scalable, highly stable Si-based metal-insulator-semiconductor photoanodes for water oxidation fabricated using thin-film reactions and electrodeposition

• Published in: Nature communications Vol. 12; no. 1; p. 3982
• Main Authors: Lee, Soonil, Ji, Li, De Palma, Alex C., Yu, Edward T.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25.06.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 147/135; 147/3; 639/166/987; 639/301/299; 639/4077/4072/4062; 639/638/439/890; Aluminum; Annealing; Aqueous solutions; Catalysts; Conduction; Corrosion; Current density; Efficiency; Electrodeposition; Fabrication; Humanities and Social Sciences; Insulating layers; Insulators; Islands; Metals; MIS (semiconductors); multidisciplinary; Nickel; Oxidation; Oxygen evolution reactions; Photoanodes; Photoelectric effect; Photoelectric emission; Saturation; Science; Science (multidisciplinary); Silicon; Stability; Thin films; Water splitting
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-24229-y

Metal-insulator-semiconductor (MIS) structures are widely used in Si-based solar water-splitting photoelectrodes to protect the Si layer from corrosion. Typically, there is a tradeoff between efficiency and stability when optimizing insulator thickness. Moreover, lithographic patterning is often required for fabricating MIS photoelectrodes. In this study, we demonstrate improved Si-based MIS photoanodes with thick insulating layers fabricated using thin-film reactions to create localized conduction paths through the insulator and electrodeposition to form metal catalyst islands. These fabrication approaches are low-cost and highly scalable, and yield MIS photoanodes with low onset potential, high saturation current density, and excellent stability. By combining this approach with a p + n-Si buried junction, further improved oxygen evolution reaction (OER) performance is achieved with an onset potential of 0.7 V versus reversible hydrogen electrode (RHE) and saturation current density of 32 mA/cm 2 under simulated AM1.5G illumination. Moreover, in stability testing in 1 M KOH aqueous solution, a constant photocurrent density of ~22 mA/cm 2 is maintained at 1.3 V versus RHE for 7 days. Authors demonstrate Si-based MIS photoanodes using Al thin-film reactions to create localized conduction paths through the insulator and Ni electrodeposition to form metal catalyst islands. These approaches yielded low onset potential, high saturation current density, and excellent stability.