Controllable synthesis of hollow and porous Ag/BiVO4 composites with enhanced visible-light photocatalytic performance

Abstract

By adjusting the amount of AgNO₃, hollow and porous silver bismuth vanadate (Ag/BiVO₄) composites were synthesized by a one-step method using ethylene glycol and water as solvents, and L-lysine as a surfactant. The as-synthesized samples were characterized by XRD, XPS, SEM, TEM (HRTEM), UV-vis DRS, PL and nitrogen adsorption–desorption techniques. The effect of the amount of AgNO₃ on the morphology of the products was investigated and using the right amount of AgNO₃ was essential to obtain the hollow and porous structure. A possible mechanism for the growth of the composites was proposed. The photocatalytic performance of the composites was evaluated for the degradation of methylene blue and rhodamine-B in an aqueous solution under visible-light irradiation. The Ag/BiVO₄ composites showed excellent photocatalytic activity at a silver content of 6.5 wt%. The 6.5 wt% Ag/BiVO₄ catalyst performed better than BiVO₄ as well as better than the Ag-doped BiVO₄ prepared by a photoreduction method. There is a strong relationship between photocatalytic performance and the structure of catalysts. It was deduced that the excellent photocatalytic activity of 6.5 wt% Ag/BiVO₄ is due to its hollow and porous structure, large specific surface area, and Ag/BiVO₄ interfaces.