pH Controlled Excellent Photocatalytic Activity of a Composite Designed from CuBi-Based Metal Organic Oxide and Graphene

A CuBi-bearing mixed metal organic oxide (MOO) combined with graphene as a heterogeneous composite photocatalyst (CuBi-MOO/Gr) has been synthesized via a one pot hydrothermal method. Raman spectroscopy data and TEM images confirm the presence of graphene on the surfaces of the crystalline particles of the as-prepared CuBi-MOO/Gr sample. The energy gap of CuBi-MOO/Gr is about 2.67 eV which means that the composite can absorb light both in visible and UV regions. The photocatalytic study of Rhodamine B (RhB) with varied pH values (from 1.82 to 11.50) using CuBi-MOO/Gr and CuBi-MOO as photocatalyst, respectively, is performed and compared indicating the high structural stability of the as-prepared CuBi-MOO/Gr composite. The unique photocatalytic results show that within 10 min almost 100% of degradation of RhB in aqueous solution is achieved at pH = 1.82 under visible light irradiation, and the composite is reusable with high stability. One very interesting phenomenon is that, at pH of 1.82, RhB is significantly observed to be adsorbed by simply adding CuBi-MOO/Gr without any light irradiation indicating CuBi-MOO/Gr is a better adsorbent for RhB than CuBi-MOO under dark acidic conditions.