Photocatalytic activity of reduced Ni-doped nonstoichiometric potassium niobate

Abstract

Photocatalytic water-splitting provides an attractive alternative for solar hydrogen prodn. due to the simplicity of the overall system in terms of light harvesting and product capture. Research has been focused recently on the development of novel and efficient visible-light photocatalysts including hybrid catalysts that contain two or more discrete catalytic materials that when combined dramatically increase the rate of the target reaction. We have synthesized and characterized the photophys. and structural properties of Ni-doped potassium niobate, K1-xNixNbO3, which has been prepd. in the presence of hydrogen. The phys. properties and structure of the new catalyst is characterized using an array of spectroscopic techniques including SEM, EDS, NMR, Raman, XPS, XRD, UV-vis diffuse reflectance, and TCSPC. Using these techniques, we have identified two primary functional sites that actively bind nano-particulate CdS. These composite catalysts exhibit enhanced photocatalytic activity for hydrogen evolution in water under visible light illumination. Hydrogen prodn. rates of 3 mmol per g per h are obtained with the hybrid catalysts under illumination at wavelengths greater than 400 nm.