Novel and Highly Active Potassium Niobate-Based Photocatalyst for Dramatically Enhanced Hydrogen Production

A novel and highly active photocatalytic material, self-doped potassium niobate composite microflowers stimulated by noble-metal-free copper nanoparticles (Cu/K4Nb6O17), was achieved. The composition and structure of the composite microflowers were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). The results showed that Cu nanoparticles were evenly and closely loaded onto the flower slices of the composite microflowers. As testified by XPS, electrochemical impedance spectrum, and fluorescence spectrum, the presence of Cu in K4Nb6O17 microflowers quickened the self-doping of Nb4+, enhanced light absorption and the unsaturated defects as active sites, and improved the separation efficiency of electron/hole pairs, which led to excellent photocatalytic activity for hydrogen evolution over the composite microflowers. Subsequently, the optimal hydrogen generation rate for the composite microflowers was about 9 times higher than that of pure K4Nb6O17 microflowers under the same conditions. Moreover, the composite photocatalyst was stable and easy to be recycled. The results demonstrated that the construction of the special heterojunction by facile interfacial modification is a promising strategy to efficiently enhance photocatalytic performance of semiconductor photo catalysts.