Controlled Electrodeposition of Nanoparticulate Tungsten Oxide

Nanoparticulate tungsten oxide films were synthesized by pulsed electrodeposition. Particle sizes between 45 and ∼330 nm were achieved by varying pulse duration from 5 to 500 ms. Shorter pulses increased the rate of new particle nucleation above the rate of existing particle growth, allowing for the observed variations in size. Cathodic deposition voltage (-1 ∼ -3 V) had little effect on particle size. Compared to films prepared by continuous electrodeposition, nanoparticulate tungsten oxide films showed a higher photoactivity and greater current density for the hydrogen intercalation reaction. Functional improvements are explained by the smaller particle size and larger surface area of nanocrystalline tungsten oxide.