Significantly Enhanced Photocatalytic Performance of Ag-doped Calcium Aluminate under Visible-light Irradiation

Abstract

Ag-doped Ca aluminate with different Ag dopant content and polycrystalline structure were obtained via a direct one-step chemical approach using Ag acetate as Ag doping source. Ag-doped Ca aluminate is composed of orthorhombic Ca₅Al₆O₁₄ and monoclinic CaAl₂O₄ phases. The morphology transformation of Ag-doped Ca aluminate from nanoflakes to microscale and nanoscale particles closely depends on Ag dopant content. Ag doping effectively improves visible-light absorption ability and 8 wt% Ag-doped Ca aluminate exhibits the lowest band gap of 1.97 eV. Ag-doped Ca aluminate shows enhanced visible-light photocatalytic activity towards gentian violet than un-doped Ca aluminate under natural sunlight irradiation. 20 mL gentian violet solution (10 mg L⁻¹) is totally degraded using 20 mg of 8 wt% Ag-doped Ca aluminate with sunlight irradiation for 30 min and reaction rate constant k of 0.034 min⁻¹. Visible-light photocatalytic activity is greatly enhanced by Ag doping owing to narrow band gap, low recombination efficiency of charge carriers, high charge transfer efficiency.