Photocatalytic hydrogen production with visible light using nanocomposites of CdS and Ni on niobium oxide

Niobium oxides (KNbO_3, K_4Nb_6O_(17)) were combined with nano-particulate CdS and Ni to form composite photocatalysts that are able to produce H_2 gas from water/ethanol solutions under visible light illumination. Ni doping was shown to affect the Nb–O bonding states, and to compete with Cd for ion exchange sites, although the Ni/CdS-doped catalysts still were found to have higher photo-catalytic activity than composite potassium niobates with nanoparticle CdS deposits alone. XPS studies showed the loss of excess Cd^(2+), but not sulfur, during the course of the photoreaction for the KNbO_3 support matrix, but significant loss of both Cd and S for the K_4Nb_6O_(17) support.