Overall water splitting by Ta3N5 nanorod single crystals grown on the edges of KTaO3 particles

Although one-step-excitation overall water splitting on a particulate photocatalyst is a simple means of performing scalable solar-to-hydrogen energy conversion, there is a lack of photocatalysts with significant activity under visible light. Despite its superior visible-light absorption, the Ta3N5 photocatalyst has not accomplished overall water splitting due to strong charge recombination at defects. Here, we show rapid growth of Ta3N5 nanorods on lattice-matched cubic KTaO3 particles through the volatilization of potassium species during a brief nitridation process. The Ta3N5 nanorods generated selectively on the edge of KTaO3 are spatially separated and well-defined single crystals free from grain boundaries. When combined with the Rh/Cr2O3 co-catalyst, the single-crystal Ta3N5 nanorods split water into hydrogen and oxygen very efficiently under visible light and simulated sunlight. Our findings demonstrate the importance of nanostructured single-crystal photocatalysts free from structural defects in solar water splitting. Ta3N5 is a semiconductor with very promising photocatalytic properties. However, performing overall water splitting with this material has remained elusive. Now, Domen and co-workers report a method for the synthesis of defect-free single-crystal Ta3N5 nanorods capable of splitting water into hydrogen and oxygen in the presence of a co-catalyst.