Electrodeposition synthesis, controllable growth, and enhanced photoluminescence of activator-doped layered gadolinium hydroxide films†

Constructing multifunctional films using layered rare earth (RE) hydroxide (LRH) nanosheets as building blocks is a popular topic. The traditional synthesis of LRH films involves four main steps: bulk crystal synthesis, intercalation of long-chain organic anions, exfoliation, and layer-by-layer self-assembly into a film. In this work, the layered gadolinium hydroxide (LGdH) film was directly synthesized via electrodeposition within 10 minutes. The effects of the synthesis conditions, including working voltage, concentration of nitrate solution, and the reaction temperature, on the structural characteristics and morphologies were investigated. In order to improve the photoluminescence performance of LGdH:RE films, the quenching groups in the LGdH structure were removed/replaced via appropriate heat treatment/anion exchange with MoO₄²⁻, based on the thermal behaviour/anion exchange properties of the LGdH, and Gd₂O₃:RE/NaGd(MoO₄)₂:RE films with enhanced photoluminescence and stability were obtained. The electrodeposition combined with heat treatment/anion exchange techniques established in this study led to the rapid synthesis of Gd₂O₃:RE/NaGd(MoO₄)₂:RE films, and could have wide implications for the generation of other types of inorganic functional films.