Research paperFabrication of two lanthanides co-doped Bi2MoO6 photocatalyst: Selection, design and mechanism of Ln1/Ln2 redox couple for enhancing photocatalytic activity

•Doping of Ln1/Ln2 redox couple can improve the photocatalytic activity of Bi2MoO6.•Selection and design of Ln1/Ln2 provide a novel strategy to fabricate photocatalysts.•A new conjecture about the complementary distribution of 4f electrons was proposed.

Various Lna/Lnb co-doped bismuth molybdate (Bi2MoO6) photocatalysts were synthesized by a hydrothermal process. The result of photocatalytic experiment demonstrated that the relevant Ln13+ 4f7+x/Ln23+ 4f7−x (Ln1/Ln2 = Tb/Eu, Dy/Sm, Er/Nd; x = 1, 2, 4) co-doped Bi2MoO6 samples shows higher photocatalytic activities. Moreover, all the photocatalytic activities of Ln1/Ln2 co-doped Bi2MoO6 were higher than that of the corresponding single-doped Bi2MoO6. The crystalline structures, morphology, constituent contents, chemical state and optical properties of the samples were analyzed in detail. Meanwhile, a new conjecture about the complementary distribution of 4f orbital electrons in the Ln1/Ln2 redox couple was proposed through co-doping with Ln1 and Ln2 ions to improve the photocatalytic activity of Bi2MoO6. For the Bi2MoO6 photcatalyst, Dy/Sm co-doping displayed the strongest photocurrent response as well as the best photocatalytic activity, while Tb/Eu co-doping displayed the apparently extended visible-light absorption region. These findings provides a novel strategy to fabricate and engineer high-efficiency photocatalysts by selecting appropriate Ln1/Ln2 redox couple.

Graphical abstractDownload high-res image (231KB)Download full-size imageBrief synopsis: Heterodinuclear redox couple engineering by co-doping of Ln1/Ln2 in Bi2MoO6 not only proposes a new conjecture about the complementary distribution between the 4f orbital electrons of Ln1 and Ln2 ions, but also provides a novel strategy to fabricate high-efficiency photocatalysts by selecting appropriate Ln1/Ln2 redox couple.