title: Controlled Sn-doping in TiO2 nanowire photoanodes with enhanced photoelectrochemical conversion.
abstract: We demonstrate for the first time the controlled Sn-doping in TiO(2) nanowire (NW) arrays for photoelectrochemical (PEC) water splitting. Because of the low lattice mismatch between SnO(2) and TiO(2), Sn dopants are incorporated into TiO(2) NWs by a one-pot hydrothermal synthesis with different ratios of SnCl(4) and tetrabutyl titanate, and a high acidity of the reactant solution is critical to control the SnCl(4) hydrolysis rate. The obtained Sn-doped TiO(2) (Sn/TiO(2)) NWs are single crystalline with a rutile structure, and the incorporation of Sn in TiO(2) NWs is well controlled at a low level, that is, 1-2% of Sn/Ti ratio, to avoid phase separation or interface scattering. PEC measurement on Sn/TiO(2) NW photoanodes with different Sn doping ratios shows that the photocurrent increases first with increased Sn doping level to >2.0 mA/cm(2) at 0 V vs Ag/AgCl under 100 mW/cm(2) simulated sunlight illumination up to ~100% enhancement compared to our best pristine TiO(2) NW photoanodes and then decreases at higher Sn doping levels. Subsequent annealing of Sn/TiO(2) NWs in H(2) further improves their photoactivity with an optimized photoconversion efficiency of ~1.2%. The incident-photon-to-current conversion efficiency shows that the photocurrent increase is mainly ascribed to the enhancement of photoactivity in the UV region, and the electrochemical impedance measurement reveals that the density of n-type charge carriers can be significantly increased by the Sn doping. These Sn/TiO(2) NW photoanodes are highly stable in PEC conversion and thus can serve as a potential candidate for pure TiO(2) materials in a variety of solar energy driven applications.
authors.affiliation: Laboratory of Advanced Materials, Department of Chemistry, Fudan University, Shanghai, 200433, People's Republic of China.
authors.forename: Ming
authors.initials: M
authors.lastname: Xu
authors.forename: Peimei
authors.initials: P
authors.lastname: Da
authors.forename: Haoyu
authors.initials: H
authors.lastname: Wu
authors.forename: Dongyuan
authors.initials: D
authors.lastname: Zhao
authors.forename: Gengfeng
authors.initials: G
authors.lastname: Zheng
mesh_terms: D004563:Electrochemistry / Q000295:instrumentation*; D004566:Electrodes; D004574:Electromagnetic Fields; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects*; D010777:Photochemistry / Q000295:instrumentation*; D014001:Tin / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D014001:Tin; D014025:Titanium