title: Surface-Electronic-State-Modulated, Single-Crystalline (001) TiO2Nanosheets for Sensitive Electrochemical Sensing of Heavy-Metal Ions.
abstract: Intrinsically low conductivity and poor reactivity restrict many semiconductors from electrochemical detection. Usually, metal- and carbon-based modifications of semiconductors are necessary, making them complex, expensive, and unstable. Here, for the first time, we present a surface-electronic-state-modulation-based concept applied to semiconductors. This concept enables pure semiconductors to be directly available for ultrasensitive electrochemical detection of heavy-metal ions without any modifications. As an example, a defective single-crystalline (001) TiO2nanosheet exhibits high electrochemical performance toward Hg(II), including a sensitivity of 270.83 μA μM-1cm-2and a detection limit of 0.017 μM, which is lower than the safety standard (0.03 μM) of drinking water established by the World Health Organization (WHO). It has been confirmed that the surface oxygen vacancy adsorbs an O2molecule while the Ti3+donates an electron, forming the O2•-species that facilitate adsorption of Hg(II) and serve as active sites for electron transfer. These findings not only extend the electrochemical sensing applications of pure semiconductors but also stimulate new opportunities for investigating atom-level electrochemical behaviors of semiconductors by surface electronic-state modulation.
authors.affiliation: Key Laboratory of Environmental Optics and Technology, Institute of Intelligent Machines, Chinese Academy of Sciences , Hefei, Anhui 230031, P.R. China.|Department of Chemistry, University of Science and Technology of China , Hefei, Anhui 230026, P.R. China.
authors.forename: Wen-Yi
authors.initials: WY
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Environmental Optics and Technology, Institute of Intelligent Machines, Chinese Academy of Sciences , Hefei, Anhui 230031, P.R. China.
authors.forename: Jin-Yun
authors.initials: JY
authors.lastname: Liu
authors.affiliation: Department of Chemistry, University of Science and Technology of China , Hefei, Anhui 230026, P.R. China.
authors.forename: Jie-Yao
authors.initials: JY
authors.lastname: Song
authors.affiliation: Department of Micro/Nano Electronics, Shanghai Jiao Tong University , Shanghai 200240, P.R. China.
authors.forename: Jin-Jin
authors.identifier: 0000-0003-4661-4051
authors.initials: JJ
authors.lastname: Li
authors.affiliation: Key Laboratory of Environmental Optics and Technology, Institute of Intelligent Machines, Chinese Academy of Sciences , Hefei, Anhui 230031, P.R. China.|Department of Chemistry, University of Science and Technology of China , Hefei, Anhui 230026, P.R. China.
authors.forename: Jin-Huai
authors.initials: JH
authors.lastname: Liu
authors.affiliation: Key Laboratory of Environmental Optics and Technology, Institute of Intelligent Machines, Chinese Academy of Sciences , Hefei, Anhui 230031, P.R. China.|Department of Chemistry, University of Science and Technology of China , Hefei, Anhui 230026, P.R. China.
authors.forename: Xing-Jiu
authors.identifier: 0000-0002-0395-4892
authors.initials: XJ
authors.lastname: Huang