Enhanced photocatalytic activity of Eu3+- and Gd3+-doped BiPO4

Novel europium- and gadolinium-doped bismuth phosphate (Eu/BiPO4 and Gd/BiPO4) microcrystals have been synthesized by a hydrothermal route. The morphologies and optical properties of the as-prepared samples were characterized carefully. Their photocatalytic activities were determined by oxidative decomposition of methylene blue (MB) in aqueous solution. The results revealed that europium and gadolinium doping greatly improves the photocatalytic efficiency of BiPO4 microcrystals. Among these as-prepared europium and gadolinium dopant samples, 1% Eu/BiPO4 and 5% Gd/BiPO4 displayed the highest photocatalytic activity, and the degradation rates are 2 and 2.7 times greater than pure BiPO4, respectively. The photodegradation reactions of MB by Eu- and Gd-BiPO4 followed first-order kinetics. The different photocatalytic mechanisms of Eu/BiPO4 and Gd/BiPO4 photocatalysts are discussed.