Growth process and enhanced photocatalytic performance of CuBi₂O₄ hierarchical microcuboids decorated with AuAg alloy nanoparticles

Abstract

CuBi₂O₄ hierarchical microcuboids self-assembled from nanorods were synthesized via a coprecipitation method, and their growth process was investigated. The as-synthesized CuBi₂O₄ hierarchical microcuboids were decorated with AuAg alloy nanoparticles via a photocatalytic reduction method. The prepared samples were systematically investigated by XRD, SEM, TEM, XPS, UV–vis DRS, EIS, PL spectroscopy and photocurrent response. RhB was chosen as the target organic pollutant to evaluate the photocatalytic activity of the samples under simulated-sunlight irradiation. It is demonstrated that the prepared CuBi₂O₄ samples exhibit excellent photocatalytic activity toward the degradation of RhB. Furthermore, the decoration of AuAg alloy nanoparticles on CuBi₂O₄ hierarchical microcuboids leads to much enhanced photocatalytic performance of the resultant AuAg–CuBi₂O₄ composite. The main reason for this is that the recombination rate of photogenerated electron–hole pairs is decreased due to the electron transfer from CuBi₂O₄ microcuboids to AuAg nanoparticles, and thus more charges are able to participate in the photocatalytic reactions. The effect of ethanol (scavenger of ·OH), BQ (scavenger of $\cdot{\text{O}}_{2}^{ - })$ and AO (scavenger of h⁺) on the dye degradation and the yield of ·OH was also investigated. Based on the experimental results, it is confirmed that ·OH is the dominant reactive species responsible for the dye degradation. The underlying photocatalytic mechanism was discussed.