Nitrogen-doped titanium nanowires and photocatalysis

Compared with undoped titanium oxide, nitrogen-doped nanowires produced 2.2 times more hydrogen by photocatalysis, according to a study by Wellia and co-authors in the Journal of Materials Science. The best sample, with the lowest dopant loading, reached 2.6 µmol per square centimeter.

The US Department of Energy sets targets for particle photocatalysis: solar-to-hydrogen efficiency of 5% for 2020 and 10% ultimately, material replacement every year and later every five, and hydrogen at US$4.60 and later US$2.10 per kilogram. The study summary reviewed reports cumulative yield, with no rate over time, solar efficiency or stability test.

That places the result at the start of the path. Between a bench gain and the first hydrogen sale lie measured efficiency, durability and scale, each with its own cost and timeline.

The useful signal for investment will be the first solar-to-hydrogen efficiency measurement comparable to the DOE targets.