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

Abstract

Recent density-functional theory calculations suggest that codoping TiO 2 with donoracceptor 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 TiO 2 with tungsten and carbon (W, C) by sequentially annealing W-precursor-coated TiO 2 nanowires in flame and carbon monoxide gas. The unique advantages of flame annealing are that the high temperature (41,000°C) and fast heating rate of flame enable rapid diffusion of W into TiO 2 without damaging the nanowire morphology and crystallinity. This is the first experimental demonstration that codoped TiO 2 :(W, C) nanowires outperform monodoped TiO 2 :W and TiO 2 :C and double the saturation photocurrent of undoped TiO 2 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.

Fabrication of titanium dioxide nanotubes in fluoride-free electrolyte via rapid breakdown anodization

“…Numerous efforts have been made to improve the photoconversion efficiency of TiO 2 . One of the most popular methods is narrowing the band gap of TiO 2 by introduce non-metal and metal dopants [17][18][19][20]. These approaches successfully shift the TiO 2 spectral response into the visible region and hence significantly increase the solar to hydrogen photoconversion efficiency.…”

Highly Efficient Solar Water Splitting from Transferred TiO2 Nanotube Arrays

“…Presumably, enhanced charge transport in reduced TNT arrays results in a minimization of charge transport resistance. 16 However, after the optimal treatment time (20 min), the samples begin to further increase in resistance, which may be attributed to the unstable interface between TNT arrays and FTO and the reduced surface area of TNT arrays caused by over-growth of TiO 2 nanoparticles from TiCl 3 (Figure S3). From the SEM observation, there are a number of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 10 To utilize the synergistic effects of the flame and solution reduction methods, that is, e...…”

Rapid and Controllable Flame Reduction of TiO2 Nanowires for Enhanced Solar Water-Splitting

“…Rutile TiO 2 NWs with an average length of 3.0 μm and diameter of 100 nm are first grown on fluorine-doped tin oxide (FTO) glass substrates by the hydrothermal method. 29,30 …”