title: Tuning surface wettability of In(x)Ga(1-x)N nanotip arrays by phosphonic acid modification and photoillumination.
abstract: We report a facile route to reversibly tune surface wettability of In(x)Ga((1-x))N (InGaN) nanotip arrays by octylphosphonic acid (OPA) modification and ultraviolet-visible (UV-vis) light illuminations. Well-aligned InGaN nanotip arrays were grown by chemical vapor deposition (CVD). OPA was covalently attached to the InGaN nanotip surface, which was initially oxidized in Piranha solution. Because of the high surface energy of polar groups, OPA-coated InGaN nanotip arrays demonstrated superhydrophobic properties (contact angle of 154°). Transitions between superhydrophobicity and hydrophilicity were obtained through OPA adsorption and UV-vis light illumination. The InGaN nanotip surface chemistry was further characterized by X-ray photoelectron spectroscopy (XPS), which suggested a scission mechanism at P-C and MO-P (M = In and Ga) bonds of bound OPA molecules. Meanwhile, no significant surface degradation was observed after the OPA modification and phototreatments.
authors.affiliation: Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 398 Ruoshui Road, Suzhou Industrial Park, Jiangsu 215123, People's Republic of China.
authors.forename: Ruigong
authors.initials: R
authors.lastname: Su
authors.forename: Haibin
authors.initials: H
authors.lastname: Liu
authors.forename: Tao
authors.initials: T
authors.lastname: Kong
authors.forename: Qin
authors.initials: Q
authors.lastname: Song
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.forename: Gang
authors.initials: G
authors.lastname: Jin
authors.forename: Guosheng
authors.initials: G
authors.lastname: Cheng