title: Codoping titanium dioxide nanowires with tungsten and carbon for enhanced photoelectrochemical performance.
abstract: Recent density-functional theory calculations suggest that codoping TiO2 with donor-acceptor pairs is more effective than monodoping for improving photoelectrochemical water-splitting performance because codoping can reduce charge recombination, improve material quality, enhance light absorption and increase solubility limits of dopants. Here we report a novel ex-situ method to codope TiO2 with tungsten and carbon (W, C) by sequentially annealing W-precursor-coated TiO2 nanowires in flame and carbon monoxide gas. The unique advantages of flame annealing are that the high temperature (>1,000 °C) and fast heating rate of flame enable rapid diffusion of W into TiO2 without damaging the nanowire morphology and crystallinity. This is the first experimental demonstration that codoped TiO2:(W, C) nanowires outperform monodoped TiO2:W and TiO2:C and double the saturation photocurrent of undoped TiO2 for photoelectrochemical water splitting. Such significant performance enhancement originates from a greatly improved electrical conductivity and activity for oxygen-evolution reaction due to the synergistic effects of codoping.
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: In Sun
authors.initials: IS
authors.lastname: Cho
authors.forename: Chi Hwan
authors.initials: CH
authors.lastname: Lee
authors.forename: Yunzhe
authors.initials: Y
authors.lastname: Feng
authors.forename: Manca
authors.initials: M
authors.lastname: Logar
authors.forename: Pratap M
authors.initials: PM
authors.lastname: Rao
authors.forename: Lili
authors.initials: L
authors.lastname: Cai
authors.forename: Dong Rip
authors.initials: DR
authors.lastname: Kim
authors.forename: Robert
authors.initials: R
authors.lastname: Sinclair
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Zheng