Hierarchical yolk-shell layered potassium niobate for tuned pH-dependent photocatalytic H2 evolution

Photocatalysts and the reaction environments in which they act are crucial for improving the photocatalytic efficiency. But the pH-dependent evolution of H-2 photocatalysed using nanoscale potassium niobate particles with high surface areas has not received attention. In this study, a straightforward Ostwald ripening method was developed to synthesize KNb3O8 with a thin nanosheet assembled hierarchical yolk-shell structure and large surface area of 60.6 m(2) g(-1). The H-2 evolution from a water-methanol solution in an alkaline to neutral environment was studied. The photocatalytic H-2 evolution rates over fabricated hierarchical yolk-shell KNb3O8 increased when OH-concentrations were decreased. Such behaviour implied that the concentration of H+ dominated the H-2 evolution over hierarchical yolk-shell KNb3O8 rather than the reduction ability from the conduction band, differing from the corresponding bulk material. This study demonstrated an efficient method to achieve a high H-2 evolution rate in a neutral environment through the use of photocatalysts with hierarchical structures and large surface areas.