Codoping titanium dioxide nanowires with tungsten and carbon for enhanced photoelectrochemical performance.

Cho, In Sun; Lee, Chi Hwan; Feng, Yunzhe; Logar, Manca; Rao, Pratap M; Cai, Lili; Kim, Dong Rip; Sinclair, Robert et al. · Nat Commun · 2013

basic_science · Level V

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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.