Silicon nanowire-hydrogenated TiO2 core-shell arrays for stable electrochemical micro-capacitors. (10th November 2021)

• Record Type: Journal Article
• Authors: Bencheikh, Yasmina; Addad, Ahmed; Coffinier, Yannick; Kumar, Umesh; Roussel, Pascal; Szunerits, Sabine; Hadjersi, Toufik; Amin, Mohammed A.; Abaidia, Seddik El hak; Boukherroub, Rabah
• Is Part Of: Electrochimica acta. Volume 396(2021)
• Publication Date: 2021-11-10
• Subjects: Silicon nanowires -- TiO2 thin film -- Hydrogenation -- Micro-capacitor -- High stability; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2021.139198
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: In this paper, we fabricated silicon nanowire-TiO2 core-shell arrays in a two-step process. First, silicon nanowire arrays (SiNW) were prepared in HF/AgNO3 aqueous solution using metal-assisted chemical etching of bulk silicon. Then, atomic layer deposition (ALD) technique was applied to coat a 20 nm thin shell TiO2 film. The TiO2 /SiNW substrates were afterward annealed at 400°C in hydrogen atmosphere for 4 h and tested as electrode materials for electrochemical micro-capacitors. The electrochemical features of the constructed H−TiO2 /SiNW electrode were assessed in an aqueous 1 M Na2 SO4 electrolyte solution and revealed that the specific capacitance increased six times compared to non-annealed TiO2 /SiNW and 20-fold compared to a reference SiNW electrode under the same operating conditions. Importantly, H−TiO2 /SiNW also displayed a high stability over 30, 000 cycles at 0.1 mA cm −2 with an overall decrease of 19% of the initial capacitance. The hydrogen treatment increased the density of hydroxyl group and enhanced the carrier density on TiO2 surface improving the capacitive properties of H−TiO2 /SiNW.