Tantalum Oxide Nanoparticles Synthesized by Thermal Chemical Vapor Deposition (CVD) Method for Photocatalytic Overall Water Splitting

Tantalum oxide nanoparticles were synthesized by a thermal CVD method using tantalum (V) ethoxide as a raw material for photocatalytic applications. Their characteristics were compared with those synthesized by a conventional hydrolysis method using same raw material. The CVD process with a set temperature of 700°C produced the nanoparticles with single crystal, small average particle size (APS) of 13 nm and necking at the edge of each nanoparticle, giving high specific surface area (SSA) of 46.5 m2/g. Computational fluid dynamics revealed that the nanoparticles were formed in the carrier gas at 530-610°C and 15 kPa in the reactor. On the other hand, conventional hydrolysis method with calcination temperature of 800°C offered the lump of tantalum oxide nanoparticles with strong aggregation, much larger APSs (32 nm) and much lower SSAs (10.1 m2/g). Evaluation of photocatalytic water splitting activities under ultraviolet irradiation (λ > 200 nm) for both the nanoparticle loaded with RuO2 as a co-catalyst showed the stable stoichiometric decomposition of H2O into H2 and O2. The CVD-derived nanoparticles gave higher decomposition rate by ≈58% than that synthesized by the hydrolysis method, which was contributed to higher SSA due to characteristics of nanoparticles necking only at the edges.