Reduced Ti-Nb-O nanotube arrays with co-doping of Nb and Ti3+/Vo as a high-performance supercapacitor electrode for enhanced electrochemical energy storage. (1st February 2023)

• Record Type: Journal Article
• Authors: Li, Tengfei; Dong, Zhenbiao; Zhao, Yuzhuang; Yuan, Yajie; Li, Zhenyu; Lin, Hualin; Han, Sheng
• Is Part Of: Electrochimica acta. Volume 440(2023)
• Publication Date: 2023-02-01
• Subjects: TiO2 nanotube arrays -- Nb-doping -- Defect engineering -- DFT calculation -- Electrochemical energy storage; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2022.141662
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: TiO2 nanotube arrays (NTAs) are excellent energy storage materials due to their chemical stability, high specific surface area and wide voltage window. However, poor electrochemical activity and electrical conductivity limit the application in supercapacitors. Herein, we develop a promising modification strategy for improving electrochemical performance of TiO2, through bulk-phase Nb-doping by in-situ anodization of Ti-Nb alloy and surface self-doping of Ti 3+ /oxygen vacancy (Vo ) with one-step electrochemical reduction. Material characterizations indicate the successful formation of Nb 5+ in the lattice, as well as Ti 3+ /Vo and hydroxyl are also introduced. Electrochemical measurements demonstrate that reduced co-doping system (denoted as R-Ti-Nb-O) yields a superior areal capacitance (19.56 mF cm −2 at 0.1 mA cm −2 ), which enhances by 3 orders of magnitude compared with pristine TiO2 . Furthermore, R-Ti-Nb-O exhibits high energy density (1.33 mWh cm −2 ), superior power density (35 mW cm −2 ), outstanding rate capability (81.70%) and remarkable cycling stability (76.76% capacitance retention after 1000 cycles). Density functional theory (DFT) calculations further reveal that reduced co-doping system indeed significantly increases the carrier density, electrical conductivity and hydrophilicity. This work involving bulk-phase Nb-doping and surface oxygen defective engineering may help provide a feasible and effective strategy to improve areal capacitance of Ti-based nanostructures for enhanced electrochemical energy storage.